diff --git a/core-java-modules/core-java-collections-maps-2/README.md b/core-java-modules/core-java-collections-maps-2/README.md new file mode 100644 index 0000000000..da9279b191 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/README.md @@ -0,0 +1,16 @@ +## Java Collections Cookbooks and Examples + +This module contains articles about Map data structures in Java. + +### Relevant Articles: +- [Map of Primitives in Java](https://www.baeldung.com/java-map-primitives) +- [Copying a HashMap in Java](https://www.baeldung.com/java-copy-hashmap) +- [A Guide to Java HashMap](https://www.baeldung.com/java-hashmap) +- [Guide to WeakHashMap in Java](https://www.baeldung.com/java-weakhashmap) +- [Map to String Conversion in Java](https://www.baeldung.com/java-map-to-string-conversion) +- [Iterate over a Map in Java](https://www.baeldung.com/java-iterate-map) +- [Merging Two Maps with Java 8](https://www.baeldung.com/java-merge-maps) +- [Sort a HashMap in Java](https://www.baeldung.com/java-hashmap-sort) +- [Finding the Highest Value in a Java Map](https://www.baeldung.com/java-find-map-max) +- [Initialize a HashMap in Java](https://www.baeldung.com/java-initialize-hashmap) +- More articles: [[<-- prev]](/core-java-collections-maps) [[next -->]](/core-java-collections-maps-3) diff --git a/core-java-modules/core-java-collections-maps-2/pom.xml b/core-java-modules/core-java-collections-maps-2/pom.xml new file mode 100644 index 0000000000..a08a4ac072 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/pom.xml @@ -0,0 +1,79 @@ + + + 4.0.0 + core-java-collections-maps-2 + 0.1.0-SNAPSHOT + core-java-collections-maps-2 + jar + + + com.baeldung + parent-java + 0.0.1-SNAPSHOT + ../../parent-java + + + + + org.eclipse.collections + eclipse-collections + ${eclipse-collections.version} + + + net.sf.trove4j + trove4j + ${trove4j.version} + + + it.unimi.dsi + fastutil + ${fastutil.version} + + + colt + colt + ${colt.version} + + + org.apache.commons + commons-lang3 + ${commons-lang3.version} + + + org.apache.commons + commons-collections4 + ${commons-collections4.version} + + + one.util + streamex + ${streamex.version} + + + com.jayway.awaitility + awaitility + ${avaitility.version} + test + + + org.assertj + assertj-core + ${assertj.version} + test + + + + + 0.6.5 + 4.1 + 1.7.0 + 8.2.0 + 3.0.2 + 8.1.0 + 1.2.0 + 3.11.1 + + + \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/Product.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/Product.java new file mode 100644 index 0000000000..5559895730 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/Product.java @@ -0,0 +1,133 @@ +package com.baeldung.map; + +import java.util.*; + +public class Product { + + private String name; + private String description; + private List tags; + + public Product(String name, String description) { + this.name = name; + this.description = description; + this.tags = new ArrayList<>(); + } + + public String getName() { + return name; + } + + public String getDescription() { + return description; + } + + public List getTags() { + return tags; + } + + public Product addTagsOfOtherProdcut(Product product) { + this.tags.addAll(product.getTags()); + return this; + } + + @Override + public boolean equals(Object o) { + + if (this == o) { + return true; + } + if (o == null || getClass() != o.getClass()) { + return false; + } + + Product product = (Product) o; + return Objects.equals(name, product.name) && + Objects.equals(description, product.description); + } + + @Override + public int hashCode() { + return Objects.hash(name, description); + } + + public static void forEach() { + + HashMap productsByName = new HashMap<>(); + productsByName.forEach( (key, product) + -> System.out.println("Key: " + key + " Product:" + product.getDescription()) + //do something with the key and value + ); + + //Prior to Java 8: + for(Map.Entry entry : productsByName.entrySet()) { + Product product = entry.getValue(); + String key = entry.getKey(); + //do something with the key and value + } + } + + public static void getOrDefault() { + + HashMap productsByName = new HashMap<>(); + Product chocolate = new Product("chocolate", "something sweet"); + Product defaultProduct = productsByName.getOrDefault("horse carriage", chocolate); + Product bike = productsByName.getOrDefault("E-Bike", chocolate); + + //Prior to Java 8: + Product bike2 = productsByName.containsKey("E-Bike") + ? productsByName.get("E-Bike") + : chocolate; + Product defaultProduct2 = productsByName.containsKey("horse carriage") + ? productsByName.get("horse carriage") + : chocolate; + } + + public static void putIfAbsent() { + + HashMap productsByName = new HashMap<>(); + Product chocolate = new Product("chocolate", "something sweet"); + productsByName.putIfAbsent("E-Bike", chocolate); + + //Prior to Java 8: + if(productsByName.containsKey("E-Bike")) { + productsByName.put("E-Bike", chocolate); + } + } + + public static void merge() { + + HashMap productsByName = new HashMap<>(); + Product eBike2 = new Product("E-Bike", "A bike with a battery"); + eBike2.getTags().add("sport"); + productsByName.merge("E-Bike", eBike2, Product::addTagsOfOtherProdcut); + + //Prior to Java 8: + if(productsByName.containsKey("E-Bike")) { + productsByName.get("E-Bike").addTagsOfOtherProdcut(eBike2); + } else { + productsByName.put("E-Bike", eBike2); + } + } + + public static void compute() { + + HashMap productsByName = new HashMap<>(); + Product eBike2 = new Product("E-Bike", "A bike with a battery"); + + productsByName.compute("E-Bike", (k,v) -> { + if(v != null) { + return v.addTagsOfOtherProdcut(eBike2); + } else { + return eBike2; + } + }); + + //Prior to Java 8: + if(productsByName.containsKey("E-Bike")) { + productsByName.get("E-Bike").addTagsOfOtherProdcut(eBike2); + } else { + productsByName.put("E-Bike", eBike2); + } + } +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/convert/MapToString.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/convert/MapToString.java new file mode 100644 index 0000000000..d13be924ff --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/convert/MapToString.java @@ -0,0 +1,34 @@ +package com.baeldung.map.convert; + +import com.google.common.base.Joiner; +import org.apache.commons.lang3.StringUtils; + +import java.util.Map; +import java.util.stream.Collectors; + +public class MapToString { + + public static String convertWithIteration(Map map) { + StringBuilder mapAsString = new StringBuilder("{"); + for (Integer key : map.keySet()) { + mapAsString.append(key + "=" + map.get(key) + ", "); + } + mapAsString.delete(mapAsString.length()-2, mapAsString.length()).append("}"); + return mapAsString.toString(); + } + + public static String convertWithStream(Map map) { + String mapAsString = map.keySet().stream() + .map(key -> key + "=" + map.get(key)) + .collect(Collectors.joining(", ", "{", "}")); + return mapAsString; + } + + public static String convertWithGuava(Map map) { + return Joiner.on(",").withKeyValueSeparator("=").join(map); + } + + public static String convertWithApache(Map map) { + return StringUtils.join(map); + } +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/convert/StringToMap.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/convert/StringToMap.java new file mode 100644 index 0000000000..416ba4dd9a --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/convert/StringToMap.java @@ -0,0 +1,21 @@ +package com.baeldung.map.convert; + +import com.google.common.base.Splitter; + +import java.util.Arrays; +import java.util.Map; +import java.util.stream.Collectors; + +public class StringToMap { + + public static Map convertWithStream(String mapAsString) { + Map map = Arrays.stream(mapAsString.split(",")) + .map(entry -> entry.split("=")) + .collect(Collectors.toMap(entry -> entry[0], entry -> entry[1])); + return map; + } + + public static Map convertWithGuava(String mapAsString) { + return Splitter.on(',').withKeyValueSeparator('=').split(mapAsString); + } +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/copyhashmap/CopyHashMap.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/copyhashmap/CopyHashMap.java new file mode 100644 index 0000000000..cb18f3aa11 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/copyhashmap/CopyHashMap.java @@ -0,0 +1,55 @@ +package com.baeldung.map.copyhashmap; + +import org.apache.commons.lang3.SerializationUtils; + +import java.util.HashMap; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Set; +import java.util.stream.Collectors; + +public class CopyHashMap { + + public static HashMap copyUsingConstructor(HashMap originalMap) { + return new HashMap(originalMap); + } + + public static HashMap copyUsingClone(HashMap originalMap) { + return (HashMap) originalMap.clone(); + } + + public static HashMap copyUsingPut(HashMap originalMap) { + HashMap shallowCopy = new HashMap(); + Set> entries = originalMap.entrySet(); + for(Map.Entry mapEntry: entries) { + shallowCopy.put(mapEntry.getKey(), mapEntry.getValue()); + } + + return shallowCopy; + } + + public static HashMap copyUsingPutAll(HashMap originalMap) { + HashMap shallowCopy = new HashMap(); + shallowCopy.putAll(originalMap); + + return shallowCopy; + } + + public static HashMap copyUsingJava8Stream(HashMap originalMap) { + Set> entries = originalMap.entrySet(); + HashMap shallowCopy = (HashMap) entries + .stream() + .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)); + + return shallowCopy; + } + + public static HashMap shallowCopy(HashMap originalMap) { + return (HashMap) originalMap.clone(); + } + + public static HashMap deepCopy(HashMap originalMap) { + return SerializationUtils.clone(originalMap); + } + +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/initialize/MapInitializer.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/initialize/MapInitializer.java new file mode 100644 index 0000000000..4d63abcfd0 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/initialize/MapInitializer.java @@ -0,0 +1,80 @@ +package com.baeldung.map.initialize; + +import java.util.AbstractMap; +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; +import java.util.stream.Collectors; +import java.util.stream.Stream; + +public class MapInitializer { + + public static Map articleMapOne; + static { + articleMapOne = new HashMap<>(); + articleMapOne.put("ar01", "Intro to Map"); + articleMapOne.put("ar02", "Some article"); + } + + public static Map createSingletonMap() { + Map passwordMap = Collections.singletonMap("username1", "password1"); + return passwordMap; + + } + + public Map createEmptyMap() { + Map emptyMap = Collections.emptyMap(); + return emptyMap; + } + + public Map createUsingDoubleBrace() { + Map doubleBraceMap = new HashMap() { + + /** + * + */ + private static final long serialVersionUID = 1L; + + { + put("key1", "value1"); + put("key2", "value2"); + } + }; + return doubleBraceMap; + } + + public Map createMapUsingStreamStringArray() { + Map map = Stream.of(new String[][] { { "Hello", "World" }, { "John", "Doe" }, }) + .collect(Collectors.toMap(data -> data[0], data -> data[1])); + + return map; + } + + public Map createMapUsingStreamObjectArray() { + Map map = Stream.of(new Object[][] { { "data1", 1 }, { "data2", 2 }, }) + .collect(Collectors.toMap(data -> (String) data[0], data -> (Integer) data[1])); + + return map; + } + + public Map createMapUsingStreamSimpleEntry() { + Map map = Stream.of(new AbstractMap.SimpleEntry<>("idea", 1), new AbstractMap.SimpleEntry<>("mobile", 2)) + .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)); + + return map; + } + + public Map createMapUsingStreamSimpleImmutableEntry() { + Map map = Stream.of(new AbstractMap.SimpleImmutableEntry<>("idea", 1), new AbstractMap.SimpleImmutableEntry<>("mobile", 2)) + .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue)); + + return map; + } + + public Map createImmutableMapWithStreams() { + Map map = Stream.of(new String[][] { { "Hello", "World" }, { "John", "Doe" }, }) + .collect(Collectors.collectingAndThen(Collectors.toMap(data -> data[0], data -> data[1]), Collections:: unmodifiableMap)); + return map; + + } +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/iteration/MapIteration.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/iteration/MapIteration.java new file mode 100644 index 0000000000..b0c32e1487 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/iteration/MapIteration.java @@ -0,0 +1,74 @@ +package com.baeldung.map.iteration; + +import java.util.HashMap; +import java.util.Iterator; +import java.util.Map; + +public class MapIteration { + + public static void main(String[] args) { + MapIteration mapIteration = new MapIteration(); + Map map = new HashMap<>(); + + map.put("One", 1); + map.put("Three", 3); + map.put("Two", 2); + + System.out.println("Iterating Keys of Map Using KeySet"); + mapIteration.iterateKeys(map); + + System.out.println("Iterating Map Using Entry Set"); + mapIteration.iterateUsingEntrySet(map); + + System.out.println("Iterating Using Iterator and Map Entry"); + mapIteration.iterateUsingIteratorAndEntry(map); + + System.out.println("Iterating Using KeySet and For Each"); + mapIteration.iterateUsingKeySetAndForeach(map); + + System.out.println("Iterating Map Using Lambda Expression"); + mapIteration.iterateUsingLambda(map); + + System.out.println("Iterating Using Stream API"); + mapIteration.iterateUsingStreamAPI(map); + } + + public void iterateUsingEntrySet(Map map) { + for (Map.Entry entry : map.entrySet()) { + System.out.println(entry.getKey() + ":" + entry.getValue()); + } + } + + public void iterateUsingLambda(Map map) { + map.forEach((k, v) -> System.out.println((k + ":" + v))); + } + + public void iterateUsingIteratorAndEntry(Map map) { + Iterator> iterator = map.entrySet() + .iterator(); + while (iterator.hasNext()) { + Map.Entry pair = iterator.next(); + System.out.println(pair.getKey() + ":" + pair.getValue()); + } + } + + public void iterateUsingKeySetAndForeach(Map map) { + for (String key : map.keySet()) { + System.out.println(key + ":" + map.get(key)); + } + } + + public void iterateUsingStreamAPI(Map map) { + map.entrySet() + .stream() + .forEach(e -> System.out.println(e.getKey() + ":" + e.getValue())); + } + + public void iterateKeys(Map map) { + for (String key : map.keySet()) { + System.out.println(key); + } + + } + +} \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mapmax/MapMax.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mapmax/MapMax.java new file mode 100644 index 0000000000..8c33c857ee --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mapmax/MapMax.java @@ -0,0 +1,92 @@ +package com.baeldung.map.mapmax; + +import java.util.*; +import java.util.Map.Entry; + +public class MapMax { + + public > V maxUsingIteration(Map map) { + + Map.Entry maxEntry = null; + + for (Map.Entry entry : map.entrySet()) { + + if (maxEntry == null || entry.getValue() + .compareTo(maxEntry.getValue()) > 0) { + maxEntry = entry; + } + } + + return maxEntry.getValue(); + } + + public > V maxUsingCollectionsMax(Map map) { + + Entry maxEntry = Collections.max(map.entrySet(), new Comparator>() { + public int compare(Entry e1, Entry e2) { + return e1.getValue() + .compareTo(e2.getValue()); + } + }); + + return maxEntry.getValue(); + } + + public > V maxUsingCollectionsMaxAndLambda(Map map) { + + Entry maxEntry = Collections.max(map.entrySet(), (Entry e1, Entry e2) -> e1.getValue() + .compareTo(e2.getValue())); + + return maxEntry.getValue(); + } + + public > V maxUsingCollectionsMaxAndMethodReference(Map map) { + + Entry maxEntry = Collections.max(map.entrySet(), Comparator.comparing(Map.Entry::getValue)); + + return maxEntry.getValue(); + } + + public > V maxUsingStreamAndLambda(Map map) { + + Optional> maxEntry = map.entrySet() + .stream() + .max((Entry e1, Entry e2) -> e1.getValue() + .compareTo(e2.getValue())); + + return maxEntry.get() + .getValue(); + } + + public > V maxUsingStreamAndMethodReference(Map map) { + + Optional> maxEntry = map.entrySet() + .stream() + .max(Comparator.comparing(Map.Entry::getValue)); + + return maxEntry.get() + .getValue(); + } + + public static void main(String[] args) { + + Map map = new HashMap(); + + map.put(1, 3); + map.put(2, 4); + map.put(3, 5); + map.put(4, 6); + map.put(5, 7); + + MapMax mapMax = new MapMax(); + + System.out.println(mapMax.maxUsingIteration(map)); + System.out.println(mapMax.maxUsingCollectionsMax(map)); + System.out.println(mapMax.maxUsingCollectionsMaxAndLambda(map)); + System.out.println(mapMax.maxUsingCollectionsMaxAndMethodReference(map)); + System.out.println(mapMax.maxUsingStreamAndLambda(map)); + System.out.println(mapMax.maxUsingStreamAndMethodReference(map)); + + } + +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mergemaps/Employee.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mergemaps/Employee.java new file mode 100644 index 0000000000..d7fb0d1a1d --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mergemaps/Employee.java @@ -0,0 +1,60 @@ +package com.baeldung.map.mergemaps; + +public class Employee implements Comparable { + + private Long id; + private String name; + + public Employee(Long id, String name) { + this.name = name; + this.id = id; + } + + public Long getId() { + return id; + } + + public void setId(Long id) { + this.id = id; + } + + public String getName() { + return name; + } + + public void setName(String name) { + this.name = name; + } + + @Override + public boolean equals(Object o) { + if (this == o) return true; + if (o == null || getClass() != o.getClass()) return false; + + Employee employee = (Employee) o; + + if (!id.equals(employee.id)) return false; + return name.equals(employee.name); + + } + + @Override + public int hashCode() { + int result = id.hashCode(); + result = 31 * result + name.hashCode(); + return result; + } + + @Override + public String toString() { + return "Employee{" + + "id=" + id + + ", name='" + name + '\'' + + '}'; + } + + @Override + public int compareTo(Employee employee) { + return (int)(this.id - employee.getId()); + } +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mergemaps/MergeMaps.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mergemaps/MergeMaps.java new file mode 100644 index 0000000000..4f187bad90 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/mergemaps/MergeMaps.java @@ -0,0 +1,105 @@ +package com.baeldung.map.mergemaps; + +import one.util.streamex.EntryStream; + +import java.util.HashMap; +import java.util.Map; +import java.util.stream.Collectors; +import java.util.stream.Stream; + +public class MergeMaps { + + private static Map map1 = new HashMap<>(); + private static Map map2 = new HashMap<>(); + + public static void main(String[] args) { + + initialize(); + + mergeFunction(); + + streamConcat(); + + streamOf(); + + streamEx(); + + streamMerge(); + } + + private static void streamMerge() { + + Map map3 = map2.entrySet() + .stream() + .collect( + Collectors.toMap( + Map.Entry::getKey, + Map.Entry::getValue, + (v1, v2) -> new Employee(v1.getId(), v2.getName()), + () -> new HashMap<>(map1) + ) + ); + + System.out.println(map3); + } + + private static void streamEx() { + Map map3 = EntryStream.of(map1) + .append(EntryStream.of(map2)) + .toMap((e1, e2) -> e1); + + System.out.println(map3); + + } + + private static void streamOf() { + Map map3 = Stream.of(map1, map2) + .flatMap(map -> map.entrySet().stream()) + .collect( + Collectors.toMap( + Map.Entry::getKey, + Map.Entry::getValue, + (v1, v2) -> new Employee(v1.getId(), v2.getName()) + ) + ); + + map3.entrySet().forEach(System.out::println); + } + + private static void streamConcat() { + Map result = Stream.concat(map1.entrySet().stream(), map2.entrySet().stream()).collect(Collectors.toMap( + Map.Entry::getKey, + Map.Entry::getValue, + (value1, value2) -> new Employee(value2.getId(), value1.getName()) + )); + + result.entrySet().forEach(System.out::println); + } + + private static void mergeFunction() { + Map map3 = new HashMap<>(map1); + + map2.forEach( + (key, value) -> map3.merge(key, value, (v1, v2) -> + new Employee(v1.getId(), v2.getName())) + ); + + map3.entrySet().forEach(System.out::println); + } + + + private static void initialize() { + Employee employee1 = new Employee(1L, "Henry"); + map1.put(employee1.getName(), employee1); + Employee employee2 = new Employee(22L, "Annie"); + map1.put(employee2.getName(), employee2); + Employee employee3 = new Employee(8L, "John"); + map1.put(employee3.getName(), employee3); + + Employee employee4 = new Employee(2L, "George"); + map2.put(employee4.getName(), employee4); + Employee employee5 = new Employee(3L, "Henry"); + map2.put(employee5.getName(), employee5); + } + +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/primitives/PrimitiveMaps.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/primitives/PrimitiveMaps.java new file mode 100644 index 0000000000..30bec12ccc --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/primitives/PrimitiveMaps.java @@ -0,0 +1,69 @@ +package com.baeldung.map.primitives; + +import cern.colt.map.AbstractIntDoubleMap; +import cern.colt.map.OpenIntDoubleHashMap; +import gnu.trove.map.TDoubleIntMap; +import gnu.trove.map.hash.TDoubleIntHashMap; +import it.unimi.dsi.fastutil.ints.Int2BooleanMap; +import it.unimi.dsi.fastutil.ints.Int2BooleanOpenHashMap; +import it.unimi.dsi.fastutil.ints.Int2BooleanSortedMap; +import it.unimi.dsi.fastutil.ints.Int2BooleanSortedMaps; +import org.eclipse.collections.api.map.primitive.ImmutableIntIntMap; +import org.eclipse.collections.api.map.primitive.MutableIntIntMap; +import org.eclipse.collections.api.map.primitive.MutableObjectDoubleMap; +import org.eclipse.collections.impl.factory.primitive.IntIntMaps; +import org.eclipse.collections.impl.factory.primitive.ObjectDoubleMaps; + +public class PrimitiveMaps { + + public static void main(String[] args) { + + eclipseCollectionsMap(); + troveMap(); + coltMap(); + fastutilMap(); + } + + private static void fastutilMap() { + Int2BooleanMap int2BooleanMap = new Int2BooleanOpenHashMap(); + int2BooleanMap.put(1, true); + int2BooleanMap.put(7, false); + int2BooleanMap.put(4, true); + + boolean value = int2BooleanMap.get(1); + + Int2BooleanSortedMap int2BooleanSorted = Int2BooleanSortedMaps.EMPTY_MAP; + } + + private static void coltMap() { + AbstractIntDoubleMap map = new OpenIntDoubleHashMap(); + map.put(1, 4.5); + double value = map.get(1); + } + + private static void eclipseCollectionsMap() { + MutableIntIntMap mutableIntIntMap = IntIntMaps.mutable.empty(); + mutableIntIntMap.addToValue(1, 1); + + ImmutableIntIntMap immutableIntIntMap = IntIntMaps.immutable.empty(); + + MutableObjectDoubleMap dObject = ObjectDoubleMaps.mutable.empty(); + dObject.addToValue("price", 150.5); + dObject.addToValue("quality", 4.4); + dObject.addToValue("stability", 0.8); + } + + private static void troveMap() { + double[] doubles = new double[] {1.2, 4.5, 0.3}; + int[] ints = new int[] {1, 4, 0}; + + TDoubleIntMap doubleIntMap = new TDoubleIntHashMap(doubles, ints); + + doubleIntMap.put(1.2, 22); + doubleIntMap.put(4.5, 16); + + doubleIntMap.adjustValue(1.2, 1); + doubleIntMap.adjustValue(4.5, 4); + doubleIntMap.adjustValue(0.3, 7); + } +} diff --git a/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/sort/SortHashMap.java b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/sort/SortHashMap.java new file mode 100644 index 0000000000..14610ffb00 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/main/java/com/baeldung/map/sort/SortHashMap.java @@ -0,0 +1,104 @@ +package com.baeldung.map.sort; + +import com.baeldung.map.mergemaps.Employee; +import com.google.common.base.Functions; +import com.google.common.collect.ImmutableSortedMap; +import com.google.common.collect.Ordering; + +import java.util.*; +import java.util.stream.Collectors; + +public class SortHashMap { + + private static Map map = new HashMap<>(); + + public static void main(String[] args) { + + initialize(); + + treeMapSortByKey(); + + arrayListSortByValue(); + arrayListSortByKey(); + + sortStream(); + + sortGuava(); + + addDuplicates(); + + treeSetByKey(); + treeSetByValue(); + + } + + private static void sortGuava() { + final Ordering naturalOrdering = + Ordering.natural().onResultOf(Functions.forMap(map, null)); + + System.out.println(ImmutableSortedMap.copyOf(map, naturalOrdering)); + } + + private static void sortStream() { + map.entrySet().stream() + .sorted(Map.Entry.comparingByKey().reversed()) + .forEach(System.out::println); + + Map result = map.entrySet().stream() + .sorted(Map.Entry.comparingByValue()) + .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, + (oldValue, newValue) -> oldValue, LinkedHashMap::new)); + + result.entrySet().forEach(System.out::println); + } + + private static void treeSetByValue() { + SortedSet values = new TreeSet<>(map.values()); + System.out.println(values); + } + + private static void treeSetByKey() { + SortedSet keysSet = new TreeSet<>(map.keySet()); + System.out.println(keysSet); + } + + private static void treeMapSortByKey() { + TreeMap sorted = new TreeMap<>(map); + sorted.putAll(map); + + sorted.entrySet().forEach(System.out::println); + + } + + private static void arrayListSortByValue() { + List employeeById = new ArrayList<>(map.values()); + + Collections.sort(employeeById); + + System.out.println(employeeById); + } + + private static void arrayListSortByKey() { + List employeeByKey = new ArrayList<>(map.keySet()); + Collections.sort(employeeByKey); + System.out.println(employeeByKey); + } + + private static void initialize() { + Employee employee1 = new Employee(1L, "Mher"); + map.put(employee1.getName(), employee1); + Employee employee2 = new Employee(22L, "Annie"); + map.put(employee2.getName(), employee2); + Employee employee3 = new Employee(8L, "John"); + map.put(employee3.getName(), employee3); + Employee employee4 = new Employee(2L, "George"); + map.put(employee4.getName(), employee4); + } + + private static void addDuplicates() { + Employee employee5 = new Employee(1L, "Mher"); + map.put(employee5.getName(), employee5); + Employee employee6 = new Employee(22L, "Annie"); + map.put(employee6.getName(), employee6); + } +} diff --git a/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/ProductUnitTest.java b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/ProductUnitTest.java new file mode 100644 index 0000000000..ba29d5c454 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/ProductUnitTest.java @@ -0,0 +1,174 @@ +package com.baeldung.map; + +import org.junit.jupiter.api.Test; + +import java.util.HashMap; +import java.util.Map; +import java.util.Objects; + +import static org.junit.jupiter.api.Assertions.*; + +class ProductUnitTest { + + + @Test + public void getExistingValue() { + HashMap productsByName = new HashMap<>(); + + Product eBike = new Product("E-Bike", "A bike with a battery"); + Product roadBike = new Product("Road bike", "A bike for competition"); + + productsByName.put(eBike.getName(), eBike); + productsByName.put(roadBike.getName(), roadBike); + + Product nextPurchase = productsByName.get("E-Bike"); + + assertEquals("A bike with a battery", nextPurchase.getDescription()); + } + + @Test + public void getNonExistingValue() { + HashMap productsByName = new HashMap<>(); + + Product eBike = new Product("E-Bike", "A bike with a battery"); + Product roadBike = new Product("Road bike", "A bike for competition"); + + productsByName.put(eBike.getName(), eBike); + productsByName.put(roadBike.getName(), roadBike); + + Product nextPurchase = productsByName.get("Car"); + + assertNull(nextPurchase); + } + + @Test + public void getExistingValueAfterSameKeyInsertedTwice() { + HashMap productsByName = new HashMap<>(); + + Product eBike = new Product("E-Bike", "A bike with a battery"); + Product roadBike = new Product("Road bike", "A bike for competition"); + Product newEBike = new Product("E-Bike", "A bike with a better battery"); + + productsByName.put(eBike.getName(), eBike); + productsByName.put(roadBike.getName(), roadBike); + productsByName.put(newEBike.getName(), newEBike); + + Product nextPurchase = productsByName.get("E-Bike"); + + assertEquals("A bike with a better battery", nextPurchase.getDescription()); + } + + @Test + public void getExistingValueWithNullKey() { + HashMap productsByName = new HashMap<>(); + + Product defaultProduct = new Product("Chocolate", "At least buy chocolate"); + + productsByName.put(null, defaultProduct); + productsByName.put(defaultProduct.getName(), defaultProduct); + + Product nextPurchase = productsByName.get(null); + assertEquals("At least buy chocolate", nextPurchase.getDescription()); + + nextPurchase = productsByName.get("Chocolate"); + assertEquals("At least buy chocolate", nextPurchase.getDescription()); + } + + @Test + public void insertSameObjectWithDifferentKey() { + HashMap productsByName = new HashMap<>(); + + Product defaultProduct = new Product("Chocolate", "At least buy chocolate"); + + productsByName.put(null, defaultProduct); + productsByName.put(defaultProduct.getName(), defaultProduct); + + assertSame(productsByName.get(null), productsByName.get("Chocolate")); + } + + @Test + public void checkIfKeyExists() { + HashMap productsByName = new HashMap<>(); + + Product eBike = new Product("E-Bike", "A bike with a battery"); + + productsByName.put(eBike.getName(), eBike); + + assertTrue(productsByName.containsKey("E-Bike")); + } + + @Test + public void checkIfValueExists() { + HashMap productsByName = new HashMap<>(); + + Product eBike = new Product("E-Bike", "A bike with a battery"); + + productsByName.put(eBike.getName(), eBike); + + assertTrue(productsByName.containsValue(eBike)); + } + + @Test + public void removeExistingKey() { + HashMap productsByName = new HashMap<>(); + + Product eBike = new Product("E-Bike", "A bike with a battery"); + Product roadBike = new Product("Road bike", "A bike for competition"); + + productsByName.put(eBike.getName(), eBike); + productsByName.put(roadBike.getName(), roadBike); + + productsByName.remove("E-Bike"); + + assertNull(productsByName.get("E-Bike")); + } + + @Test + public void givenMutableKeyWhenKeyChangeThenValueNotFound() { + // Given + MutableKey key = new MutableKey("initial"); + + Map items = new HashMap<>(); + items.put(key, "success"); + + // When + key.setName("changed"); + + // Then + assertNull(items.get(key)); + } + + static class MutableKey { + private String name; + + public MutableKey(String name) { + this.name = name; + } + + public String getName() { + return name; + } + + public void setName(String name) { + this.name = name; + } + + @Override + public boolean equals(Object o) { + if (this == o) { + return true; + } + if (o == null || getClass() != o.getClass()) { + return false; + } + MutableKey that = (MutableKey) o; + return Objects.equals(name, that.name); + } + + @Override + public int hashCode() { + return Objects.hash(name); + } + } + +} diff --git a/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/convert/MapToStringUnitTest.java b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/convert/MapToStringUnitTest.java new file mode 100644 index 0000000000..4517dea328 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/convert/MapToStringUnitTest.java @@ -0,0 +1,48 @@ +package com.baeldung.map.convert; + +import org.apache.commons.collections4.MapUtils; +import org.junit.Assert; +import org.junit.jupiter.api.BeforeEach; +import org.junit.jupiter.api.Test; + +import java.util.HashMap; +import java.util.Map; + +public class MapToStringUnitTest { + + private Map wordsByKey = new HashMap<>(); + + @BeforeEach + public void setup() { + wordsByKey.clear(); + wordsByKey.put(1, "one"); + wordsByKey.put(2, "two"); + wordsByKey.put(3, "three"); + wordsByKey.put(4, "four"); + } + + @Test + public void givenMap_WhenUsingIteration_ThenResultingMapIsCorrect() { + String mapAsString = MapToString.convertWithIteration(wordsByKey); + Assert.assertEquals("{1=one, 2=two, 3=three, 4=four}", mapAsString); + } + + @Test + public void givenMap_WhenUsingStream_ThenResultingMapIsCorrect() { + String mapAsString = MapToString.convertWithStream(wordsByKey); + Assert.assertEquals("{1=one, 2=two, 3=three, 4=four}", mapAsString); + } + + @Test + public void givenMap_WhenUsingGuava_ThenResultingMapIsCorrect() { + String mapAsString = MapToString.convertWithGuava(wordsByKey); + Assert.assertEquals("1=one,2=two,3=three,4=four", mapAsString); + } + + @Test + public void givenMap_WhenUsingApache_ThenResultingMapIsCorrect() { + String mapAsString = MapToString.convertWithApache(wordsByKey); + Assert.assertEquals("{1=one, 2=two, 3=three, 4=four}", mapAsString); + MapUtils.debugPrint(System.out, "Map as String", wordsByKey); + } +} \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/convert/StringToMapUnitTest.java b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/convert/StringToMapUnitTest.java new file mode 100644 index 0000000000..2f80b30871 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/convert/StringToMapUnitTest.java @@ -0,0 +1,23 @@ +package com.baeldung.map.convert; + +import org.junit.Assert; +import org.junit.jupiter.api.Test; + +import java.util.Map; + +public class StringToMapUnitTest { + + @Test + public void givenString_WhenUsingStream_ThenResultingStringIsCorrect() { + Map wordsByKey = StringToMap.convertWithStream("1=one,2=two,3=three,4=four"); + Assert.assertEquals(4, wordsByKey.size()); + Assert.assertEquals("one", wordsByKey.get("1")); + } + + @Test + void givenString_WhenUsingGuava_ThenResultingStringIsCorrect() { + Map wordsByKey = StringToMap.convertWithGuava("1=one,2=two,3=three,4=four"); + Assert.assertEquals(4, wordsByKey.size()); + Assert.assertEquals("one", wordsByKey.get("1")); + } +} \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/copyhashmap/CopyHashMapUnitTest.java b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/copyhashmap/CopyHashMapUnitTest.java new file mode 100644 index 0000000000..e2d5e327e1 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/copyhashmap/CopyHashMapUnitTest.java @@ -0,0 +1,76 @@ +package com.baeldung.map.copyhashmap; + +import com.google.common.collect.ImmutableMap; +import org.junit.Test; + +import java.util.HashMap; +import java.util.Map; + +import static org.assertj.core.api.Assertions.assertThat; + +public class CopyHashMapUnitTest { + + @Test + public void givenHashMap_whenShallowCopy_thenCopyisNotSameAsOriginal() { + + HashMap map = new HashMap<>(); + Employee emp1 = new Employee("John"); + Employee emp2 = new Employee("Norman"); + map.put("emp1",emp1); + map.put("emp2",emp2); + + HashMap shallowCopy = CopyHashMap.shallowCopy(map); + + assertThat(shallowCopy).isNotSameAs(map); + + } + + @Test + public void givenHashMap_whenShallowCopyModifyingOriginalObject_thenCopyShouldChange() { + + HashMap map = new HashMap<>(); + Employee emp1 = new Employee("John"); + Employee emp2 = new Employee("Norman"); + map.put("emp1",emp1); + map.put("emp2",emp2); + + HashMap shallowCopy = CopyHashMap.shallowCopy(map); + + emp1.setName("Johny"); + + assertThat(shallowCopy.get("emp1")).isEqualTo(map.get("emp1")); + + } + + @Test + public void givenHashMap_whenDeepCopyModifyingOriginalObject_thenCopyShouldNotChange() { + + HashMap map = new HashMap<>(); + Employee emp1 = new Employee("John"); + Employee emp2 = new Employee("Norman"); + map.put("emp1",emp1); + map.put("emp2",emp2); + HashMap deepCopy = CopyHashMap.deepCopy(map); + + emp1.setName("Johny"); + + assertThat(deepCopy.get("emp1")).isNotEqualTo(map.get("emp1")); + + } + + @Test + public void givenImmutableMap_whenCopyUsingGuava_thenCopyShouldNotChange() { + Employee emp1 = new Employee("John"); + Employee emp2 = new Employee("Norman"); + + Map map = ImmutableMap. builder() + .put("emp1",emp1) + .put("emp2",emp2) + .build(); + Map shallowCopy = ImmutableMap.copyOf(map); + + assertThat(shallowCopy).isSameAs(map); + + } + +} diff --git a/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/copyhashmap/Employee.java b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/copyhashmap/Employee.java new file mode 100644 index 0000000000..5db55c26ea --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/copyhashmap/Employee.java @@ -0,0 +1,28 @@ +package com.baeldung.map.copyhashmap; + +import java.io.Serializable; + +public class Employee implements Serializable{ + + private String name; + + public Employee(String name) { + super(); + this.name = name; + } + public String getName() { + return name; + } + + public void setName(String name) { + this.name = name; + } + + @Override + public String toString() { + return this.name; + } + +} + + diff --git a/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/initialize/MapInitializerUnitTest.java b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/initialize/MapInitializerUnitTest.java new file mode 100644 index 0000000000..7c6dffe787 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/initialize/MapInitializerUnitTest.java @@ -0,0 +1,27 @@ +package com.baeldung.map.initialize; + +import org.junit.Test; + +import java.util.Map; + +import static org.junit.Assert.assertEquals; + +public class MapInitializerUnitTest { + + @Test + public void givenStaticMap_whenUpdated_thenCorrect() { + + MapInitializer.articleMapOne.put("NewArticle1", "Convert array to List"); + + assertEquals(MapInitializer.articleMapOne.get("NewArticle1"), "Convert array to List"); + + } + + @Test(expected=UnsupportedOperationException.class) + public void givenSingleTonMap_whenEntriesAdded_throwsException() { + + Map map = MapInitializer.createSingletonMap(); + map.put("username2", "password2"); + } + +} diff --git a/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/mapmax/MapMaxUnitTest.java b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/mapmax/MapMaxUnitTest.java new file mode 100644 index 0000000000..30b945bfc8 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/mapmax/MapMaxUnitTest.java @@ -0,0 +1,58 @@ +package com.baeldung.map.mapmax; + + +import org.junit.Before; +import org.junit.Test; + +import java.util.HashMap; +import java.util.Map; + +import static org.junit.Assert.assertEquals; + +public class MapMaxUnitTest { + + Map map = null; + MapMax mapMax = null; + + + @Before + public void setupTestData() { + map = new HashMap(); + map.put(23, 12); + map.put(46, 24); + map.put(27, 38); + mapMax = new MapMax(); + } + + @Test + public void givenMap_whenIterated_thenReturnMaxValue() { + assertEquals(new Integer(38), mapMax.maxUsingIteration(map)); + } + + @Test + public void givenMap_whenUsingCollectionsMax_thenReturnMaxValue() { + assertEquals(new Integer(38), mapMax.maxUsingCollectionsMax(map)); + } + + @Test + public void givenMap_whenUsingCollectionsMaxAndLambda_thenReturnMaxValue() { + assertEquals(new Integer(38), mapMax.maxUsingCollectionsMaxAndLambda(map)); + } + + @Test + public void givenMap_whenUsingCollectionsMaxAndMethodReference_thenReturnMaxValue() { + assertEquals(new Integer(38), mapMax.maxUsingCollectionsMaxAndMethodReference(map)); + } + + @Test + public void givenMap_whenUsingStreamAndLambda_thenReturnMaxValue() { + assertEquals(new Integer(38), mapMax.maxUsingStreamAndLambda(map)); + } + + @Test + public void givenMap_whenUsingStreamAndMethodReference_thenReturnMaxValue() { + assertEquals(new Integer(38), mapMax.maxUsingStreamAndMethodReference (map)); + } + + +} diff --git a/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/weakhashmap/WeakHashMapUnitTest.java b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/weakhashmap/WeakHashMapUnitTest.java new file mode 100644 index 0000000000..293f24c378 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-2/src/test/java/com/baeldung/map/weakhashmap/WeakHashMapUnitTest.java @@ -0,0 +1,72 @@ +package com.baeldung.map.weakhashmap; + + +import org.junit.Test; + +import java.util.WeakHashMap; +import java.util.concurrent.TimeUnit; + +import static com.jayway.awaitility.Awaitility.await; +import static org.junit.Assert.assertTrue; + +public class WeakHashMapUnitTest { + + @Test + public void givenWeakHashMap_whenCacheValueThatHasNoReferenceToIt_GCShouldReclaimThatObject() { + //given + WeakHashMap map = new WeakHashMap<>(); + BigImage bigImage = new BigImage("image_id"); + UniqueImageName imageName = new UniqueImageName("name_of_big_image"); + + map.put(imageName, bigImage); + assertTrue(map.containsKey(imageName)); + + //when big image key is not reference anywhere + imageName = null; + System.gc(); + + //then GC will finally reclaim that object + await().atMost(10, TimeUnit.SECONDS).until(map::isEmpty); + } + + @Test + public void givenWeakHashMap_whenCacheValueThatHasNoReferenceToIt_GCShouldReclaimThatObjectButLeaveReferencedObject() { + //given + WeakHashMap map = new WeakHashMap<>(); + BigImage bigImageFirst = new BigImage("foo"); + UniqueImageName imageNameFirst = new UniqueImageName("name_of_big_image"); + + BigImage bigImageSecond = new BigImage("foo_2"); + UniqueImageName imageNameSecond = new UniqueImageName("name_of_big_image_2"); + + map.put(imageNameFirst, bigImageFirst); + map.put(imageNameSecond, bigImageSecond); + assertTrue(map.containsKey(imageNameFirst)); + assertTrue(map.containsKey(imageNameSecond)); + + //when + imageNameFirst = null; + System.gc(); + + //then + await().atMost(10, TimeUnit.SECONDS).until(() -> map.size() == 1); + await().atMost(10, TimeUnit.SECONDS).until(() -> map.containsKey(imageNameSecond)); + } + + + class BigImage { + public final String imageId; + + BigImage(String imageId) { + this.imageId = imageId; + } + } + + class UniqueImageName { + public final String imageName; + + UniqueImageName(String imageName) { + this.imageName = imageName; + } + } +} diff --git a/core-java-modules/core-java-collections-maps-3/README.md b/core-java-modules/core-java-collections-maps-3/README.md new file mode 100644 index 0000000000..142aa34800 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-3/README.md @@ -0,0 +1,8 @@ +## Java Collections Cookbooks and Examples + +This module contains articles about Map data structures in Java. + +### Relevant Articles: +- [Java TreeMap vs HashMap](https://www.baeldung.com/java-treemap-vs-hashmap) +- [Comparing Two HashMaps in Java](https://www.baeldung.com/java-compare-hashmaps) +- More articles: [[<-- prev]](/core-java-collections-maps-2) diff --git a/core-java-modules/core-java-collections-maps-3/pom.xml b/core-java-modules/core-java-collections-maps-3/pom.xml new file mode 100644 index 0000000000..95414c12c2 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-3/pom.xml @@ -0,0 +1,26 @@ + + + 4.0.0 + core-java-collections-maps-3 + 0.1.0-SNAPSHOT + core-java-collections-maps-3 + jar + + + com.baeldung + parent-java + 0.0.1-SNAPSHOT + ../../parent-java + + + + + + + + + + + \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps-3/src/test/java/com/baeldung/map/compare/HashMapComparisonUnitTest.java b/core-java-modules/core-java-collections-maps-3/src/test/java/com/baeldung/map/compare/HashMapComparisonUnitTest.java new file mode 100644 index 0000000000..0edd0cd87b --- /dev/null +++ b/core-java-modules/core-java-collections-maps-3/src/test/java/com/baeldung/map/compare/HashMapComparisonUnitTest.java @@ -0,0 +1,225 @@ +package com.baeldung.map.compare; + +import com.google.common.base.Equivalence; +import com.google.common.collect.MapDifference; +import com.google.common.collect.MapDifference.ValueDifference; +import com.google.common.collect.Maps; +import org.junit.Before; +import org.junit.Test; + +import java.util.Arrays; +import java.util.HashMap; +import java.util.Map; +import java.util.stream.Collectors; + +import static org.hamcrest.MatcherAssert.assertThat; +import static org.hamcrest.collection.IsMapContaining.hasEntry; +import static org.hamcrest.collection.IsMapContaining.hasKey; +import static org.junit.Assert.*; + +public class HashMapComparisonUnitTest { + + Map asiaCapital1; + Map asiaCapital2; + Map asiaCapital3; + + Map asiaCity1; + Map asiaCity2; + Map asiaCity3; + + @Before + public void setup(){ + asiaCapital1 = new HashMap(); + asiaCapital1.put("Japan", "Tokyo"); + asiaCapital1.put("South Korea", "Seoul"); + + asiaCapital2 = new HashMap(); + asiaCapital2.put("South Korea", "Seoul"); + asiaCapital2.put("Japan", "Tokyo"); + + asiaCapital3 = new HashMap(); + asiaCapital3.put("Japan", "Tokyo"); + asiaCapital3.put("China", "Beijing"); + + asiaCity1 = new HashMap(); + asiaCity1.put("Japan", new String[] { "Tokyo", "Osaka" }); + asiaCity1.put("South Korea", new String[] { "Seoul", "Busan" }); + + asiaCity2 = new HashMap(); + asiaCity2.put("South Korea", new String[] { "Seoul", "Busan" }); + asiaCity2.put("Japan", new String[] { "Tokyo", "Osaka" }); + + asiaCity3 = new HashMap(); + asiaCity3.put("Japan", new String[] { "Tokyo", "Osaka" }); + asiaCity3.put("China", new String[] { "Beijing", "Hong Kong" }); + } + + @Test + public void whenCompareTwoHashMapsUsingEquals_thenSuccess() { + assertTrue(asiaCapital1.equals(asiaCapital2)); + assertFalse(asiaCapital1.equals(asiaCapital3)); + } + + @Test + public void whenCompareTwoHashMapsWithArrayValuesUsingEquals_thenFail() { + assertFalse(asiaCity1.equals(asiaCity2)); + } + + @Test + public void whenCompareTwoHashMapsUsingStreamAPI_thenSuccess() { + assertTrue(areEqual(asiaCapital1, asiaCapital2)); + assertFalse(areEqual(asiaCapital1, asiaCapital3)); + } + + @Test + public void whenCompareTwoHashMapsWithArrayValuesUsingStreamAPI_thenSuccess() { + assertTrue(areEqualWithArrayValue(asiaCity1, asiaCity2)); + assertFalse(areEqualWithArrayValue(asiaCity1, asiaCity3)); + } + + @Test + public void whenCompareTwoHashMapKeys_thenSuccess() { + assertTrue(asiaCapital1.keySet().equals(asiaCapital2.keySet())); + assertFalse(asiaCapital1.keySet().equals(asiaCapital3.keySet())); + } + + @Test + public void whenCompareTwoHashMapKeyValuesUsingStreamAPI_thenSuccess() { + Map asiaCapital3 = new HashMap(); + asiaCapital3.put("Japan", "Tokyo"); + asiaCapital3.put("South Korea", "Seoul"); + asiaCapital3.put("China", "Beijing"); + + Map asiaCapital4 = new HashMap(); + asiaCapital4.put("South Korea", "Seoul"); + asiaCapital4.put("Japan", "Osaka"); + asiaCapital4.put("China", "Beijing"); + + Map result = areEqualKeyValues(asiaCapital3, asiaCapital4); + + assertEquals(3, result.size()); + assertThat(result, hasEntry("Japan", false)); + assertThat(result, hasEntry("South Korea", true)); + assertThat(result, hasEntry("China", true)); + } + + @Test + public void givenDifferentMaps_whenGetDiffUsingGuava_thenSuccess() { + Map asia1 = new HashMap(); + asia1.put("Japan", "Tokyo"); + asia1.put("South Korea", "Seoul"); + asia1.put("India", "New Delhi"); + + Map asia2 = new HashMap(); + asia2.put("Japan", "Tokyo"); + asia2.put("China", "Beijing"); + asia2.put("India", "Delhi"); + + MapDifference diff = Maps.difference(asia1, asia2); + Map> entriesDiffering = diff.entriesDiffering(); + + assertFalse(diff.areEqual()); + assertEquals(1, entriesDiffering.size()); + assertThat(entriesDiffering, hasKey("India")); + assertEquals("New Delhi", entriesDiffering.get("India").leftValue()); + assertEquals("Delhi", entriesDiffering.get("India").rightValue()); + } + + @Test + public void givenDifferentMaps_whenGetEntriesOnOneSideUsingGuava_thenSuccess() { + Map asia1 = new HashMap(); + asia1.put("Japan", "Tokyo"); + asia1.put("South Korea", "Seoul"); + asia1.put("India", "New Delhi"); + + Map asia2 = new HashMap(); + asia2.put("Japan", "Tokyo"); + asia2.put("China", "Beijing"); + asia2.put("India", "Delhi"); + + MapDifference diff = Maps.difference(asia1, asia2); + Map entriesOnlyOnRight = diff.entriesOnlyOnRight(); + Map entriesOnlyOnLeft = diff.entriesOnlyOnLeft(); + + assertEquals(1, entriesOnlyOnRight.size()); + assertThat(entriesOnlyOnRight, hasEntry("China", "Beijing")); + assertEquals(1, entriesOnlyOnLeft.size()); + assertThat(entriesOnlyOnLeft, hasEntry("South Korea", "Seoul")); + } + + @Test + public void givenDifferentMaps_whenGetCommonEntriesUsingGuava_thenSuccess() { + Map asia1 = new HashMap(); + asia1.put("Japan", "Tokyo"); + asia1.put("South Korea", "Seoul"); + asia1.put("India", "New Delhi"); + + Map asia2 = new HashMap(); + asia2.put("Japan", "Tokyo"); + asia2.put("China", "Beijing"); + asia2.put("India", "Delhi"); + + MapDifference diff = Maps.difference(asia1, asia2); + Map entriesInCommon = diff.entriesInCommon(); + + assertEquals(1, entriesInCommon.size()); + assertThat(entriesInCommon, hasEntry("Japan", "Tokyo")); + } + + @Test + public void givenSimilarMapsWithArrayValue_whenCompareUsingGuava_thenFail() { + MapDifference diff = Maps.difference(asiaCity1, asiaCity2); + assertFalse(diff.areEqual()); + } + + @Test + public void givenSimilarMapsWithArrayValue_whenCompareUsingGuavaEquivalence_thenSuccess() { + Equivalence eq = new Equivalence() { + @Override + protected boolean doEquivalent(String[] a, String[] b) { + return Arrays.equals(a, b); + } + + @Override + protected int doHash(String[] value) { + return value.hashCode(); + } + }; + + MapDifference diff = Maps.difference(asiaCity1, asiaCity2, eq); + assertTrue(diff.areEqual()); + + diff = Maps.difference(asiaCity1, asiaCity3, eq); + assertFalse(diff.areEqual()); + } + + // =========================================================================== + + private boolean areEqual(Map first, Map second) { + if (first.size() != second.size()) { + return false; + } + + return first.entrySet() + .stream() + .allMatch(e -> e.getValue() + .equals(second.get(e.getKey()))); + } + + private boolean areEqualWithArrayValue(Map first, Map second) { + if (first.size() != second.size()) { + return false; + } + + return first.entrySet() + .stream() + .allMatch(e -> Arrays.equals(e.getValue(), second.get(e.getKey()))); + } + + private Map areEqualKeyValues(Map first, Map second) { + return first.entrySet() + .stream() + .collect(Collectors.toMap(e -> e.getKey(), e -> e.getValue().equals(second.get(e.getKey())))); + } + +} diff --git a/core-java-modules/core-java-collections-maps-3/src/test/java/com/baeldung/map/treemaphashmap/TreeMapVsHashMapUnitTest.java b/core-java-modules/core-java-collections-maps-3/src/test/java/com/baeldung/map/treemaphashmap/TreeMapVsHashMapUnitTest.java new file mode 100644 index 0000000000..1057e3b9f0 --- /dev/null +++ b/core-java-modules/core-java-collections-maps-3/src/test/java/com/baeldung/map/treemaphashmap/TreeMapVsHashMapUnitTest.java @@ -0,0 +1,58 @@ +package com.baeldung.map.treemaphashmap; + +import org.hamcrest.Matchers; +import org.junit.Assert; +import org.junit.Test; + +import java.util.HashMap; +import java.util.Map; +import java.util.TreeMap; + +public class TreeMapVsHashMapUnitTest { + + @Test + public void whenInsertObjectsTreeMap_thenNaturalOrder() { + Map treemap = new TreeMap<>(); + treemap.put(3, "TreeMap"); + treemap.put(2, "vs"); + treemap.put(1, "HashMap"); + Assert.assertThat(treemap.keySet(), Matchers.contains(1, 2, 3)); + } + + @Test(expected = NullPointerException.class) + public void whenInsertNullInTreeMap_thenException() { + Map treemap = new TreeMap<>(); + treemap.put(null, "NullPointerException"); + } + + @Test + public void whenInsertObjectsHashMap_thenRandomOrder() { + Map hashmap = new HashMap<>(); + hashmap.put(3, "TreeMap"); + hashmap.put(2, "vs"); + hashmap.put(1, "HashMap"); + Assert.assertThat(hashmap.keySet(), Matchers.containsInAnyOrder(1, 2, 3)); + } + + @Test + public void whenInsertNullInHashMap_thenInsertsNull() { + Map hashmap = new HashMap<>(); + hashmap.put(null, null); + Assert.assertNull(hashmap.get(null)); + } + + @Test + public void givenHashMapAndTreeMap_whenputDuplicates_thenOnlyUnique() { + Map treeMap = new HashMap<>(); + treeMap.put(1, "Baeldung"); + treeMap.put(1, "Baeldung"); + + Assert.assertTrue(treeMap.size() == 1); + + Map treeMap2 = new TreeMap<>(); + treeMap2.put(1, "Baeldung"); + treeMap2.put(1, "Baeldung"); + + Assert.assertTrue(treeMap2.size() == 1); + } +} \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps/README.md b/core-java-modules/core-java-collections-maps/README.md new file mode 100644 index 0000000000..1323fb97cd --- /dev/null +++ b/core-java-modules/core-java-collections-maps/README.md @@ -0,0 +1,16 @@ +## Java Collections Cookbooks and Examples + +This module contains articles about Map data structures in Java. + +### Relevant Articles: +- [Guide to the Guava BiMap](https://www.baeldung.com/guava-bimap) +- [A Guide to Java HashMap](https://www.baeldung.com/java-hashmap) +- [A Guide to LinkedHashMap in Java](https://www.baeldung.com/java-linked-hashmap) +- [A Guide to TreeMap in Java](https://www.baeldung.com/java-treemap) +- [How to Store Duplicate Keys in a Map in Java?](https://www.baeldung.com/java-map-duplicate-keys) +- [Get the Key for a Value from a Java Map](https://www.baeldung.com/java-map-key-from-value) +- [How to Check If a Key Exists in a Map](https://www.baeldung.com/java-map-key-exists) +- [Immutable Map Implementations in Java](https://www.baeldung.com/java-immutable-maps) +- [Guide to Apache Commons MultiValuedMap](https://www.baeldung.com/apache-commons-multi-valued-map) +- [The Java HashMap Under the Hood](https://www.baeldung.com/java-hashmap-advanced) +- More articles: [[next -->]](/core-java-collections-maps-2) diff --git a/core-java-modules/core-java-collections-maps/pom.xml b/core-java-modules/core-java-collections-maps/pom.xml new file mode 100644 index 0000000000..c0dd705c1c --- /dev/null +++ b/core-java-modules/core-java-collections-maps/pom.xml @@ -0,0 +1,35 @@ + + + 4.0.0 + core-java-collections-maps + 0.1.0-SNAPSHOT + core-java-collections-maps + jar + + + com.baeldung + parent-java + 0.0.1-SNAPSHOT + ../../parent-java + + + + + org.apache.commons + commons-collections4 + ${commons-collections4.version} + + + org.assertj + assertj-core + ${assertj.version} + test + + + + + 4.1 + 3.6.1 + + diff --git a/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MapUtil.java b/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MapUtil.java new file mode 100644 index 0000000000..91b7197a92 --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MapUtil.java @@ -0,0 +1,44 @@ +/** + * + */ +package com.baeldung.map; + +import java.util.HashSet; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Set; +import java.util.stream.Stream; + +/** + * @author swpraman + * + */ +public class MapUtil { + + public static Stream keys(Map map, V value) { + return map.entrySet() + .stream() + .filter(entry -> value.equals(entry.getValue())) + .map(Map.Entry::getKey); + } + + public static Set getKeys(Map map, V value) { + Set keys = new HashSet<>(); + for (Entry entry : map.entrySet()) { + if (entry.getValue().equals(value)) { + keys.add(entry.getKey()); + } + } + return keys; + } + + public static K getKey(Map map, V value) { + for (Entry entry : map.entrySet()) { + if (entry.getValue().equals(value)) { + return entry.getKey(); + } + } + return null; + } + +} diff --git a/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MyKey.java b/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MyKey.java new file mode 100644 index 0000000000..9993d7862c --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MyKey.java @@ -0,0 +1,64 @@ +package com.baeldung.map; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +public class MyKey { + private static final Logger LOG = LoggerFactory.getLogger(MyKey.class); + + private String name; + private int id; + + public MyKey(int id, String name) { + this.id = id; + this.name = name; + } + + public String getName() { + return name; + } + + public void setName(String name) { + this.name = name; + } + + public int getId() { + return id; + } + + public void setId(int id) { + this.id = id; + } + + @Override + public int hashCode() { + LOG.debug("Calling hashCode()"); + return id; + } + + @Override + public String toString() { + return "MyKey [name=" + name + ", id=" + id + "]"; + } + + @Override + public boolean equals(Object obj) { + LOG.debug("Calling equals() for key: " + obj); + if (this == obj) + return true; + if (obj == null) + return false; + if (getClass() != obj.getClass()) + return false; + MyKey other = (MyKey) obj; + if (id != other.id) + return false; + if (name == null) { + if (other.name != null) + return false; + } else if (!name.equals(other.name)) + return false; + return true; + } + +} diff --git a/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MyLinkedHashMap.java b/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MyLinkedHashMap.java new file mode 100644 index 0000000000..b687e57d85 --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/main/java/com/baeldung/map/MyLinkedHashMap.java @@ -0,0 +1,23 @@ +package com.baeldung.map; + +import java.util.LinkedHashMap; +import java.util.Map; + +public class MyLinkedHashMap extends LinkedHashMap { + + /** + * + */ + private static final long serialVersionUID = 1L; + private static final int MAX_ENTRIES = 5; + + public MyLinkedHashMap(int initialCapacity, float loadFactor, boolean accessOrder) { + super(initialCapacity, loadFactor, accessOrder); + } + + @Override + protected boolean removeEldestEntry(Map.Entry eldest) { + return size() > MAX_ENTRIES; + } + +} diff --git a/core-java-modules/core-java-collections-maps/src/main/resources/logback.xml b/core-java-modules/core-java-collections-maps/src/main/resources/logback.xml new file mode 100644 index 0000000000..7d900d8ea8 --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/main/resources/logback.xml @@ -0,0 +1,13 @@ + + + + + %d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n + + + + + + + + \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/guava/GuavaBiMapUnitTest.java b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/guava/GuavaBiMapUnitTest.java new file mode 100644 index 0000000000..b44d2db1aa --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/guava/GuavaBiMapUnitTest.java @@ -0,0 +1,120 @@ +package com.baeldung.guava; + +import static org.junit.Assert.*; +import java.util.HashMap; +import java.util.Map; +import org.junit.Test; +import com.google.common.collect.BiMap; +import com.google.common.collect.EnumHashBiMap; +import com.google.common.collect.HashBiMap; +import com.google.common.collect.ImmutableBiMap; + +public class GuavaBiMapUnitTest { + @Test + public void whenQueryByValue_returnsKey() { + final BiMap capitalCountryBiMap = HashBiMap.create(); + capitalCountryBiMap.put("New Delhi", "India"); + capitalCountryBiMap.put("Washingon, D.C.", "USA"); + capitalCountryBiMap.put("Moscow", "Russia"); + + final String countryCapitalName = capitalCountryBiMap.inverse().get("India"); + + assertEquals("New Delhi", countryCapitalName); + } + + @Test + public void whenCreateBiMapFromExistingMap_returnsKey() { + final Map capitalCountryMap = new HashMap<>(); + capitalCountryMap.put("New Delhi", "India"); + capitalCountryMap.put("Washingon, D.C.", "USA"); + capitalCountryMap.put("Moscow", "Russia"); + final BiMap capitalCountryBiMap = HashBiMap.create(capitalCountryMap); + + final String countryCapitalName = capitalCountryBiMap.inverse().get("India"); + + assertEquals("New Delhi", countryCapitalName); + } + + @Test + public void whenQueryByKey_returnsValue() { + final BiMap capitalCountryBiMap = HashBiMap.create(); + + capitalCountryBiMap.put("New Delhi", "India"); + capitalCountryBiMap.put("Washingon, D.C.", "USA"); + capitalCountryBiMap.put("Moscow", "Russia"); + + assertEquals("USA", capitalCountryBiMap.get("Washingon, D.C.")); + } + + @Test(expected = IllegalArgumentException.class) + public void whenSameValueIsPresent_throwsException() { + final BiMap capitalCountryBiMap = HashBiMap.create(); + + capitalCountryBiMap.put("New Delhi", "India"); + capitalCountryBiMap.put("Washingon, D.C.", "USA"); + capitalCountryBiMap.put("Moscow", "Russia"); + capitalCountryBiMap.put("Trump", "USA"); + } + + @Test + public void givenSameValueIsPresent_whenForcePut_completesSuccessfully() { + final BiMap capitalCountryBiMap = HashBiMap.create(); + + capitalCountryBiMap.put("New Delhi", "India"); + capitalCountryBiMap.put("Washingon, D.C.", "USA"); + capitalCountryBiMap.put("Moscow", "Russia"); + capitalCountryBiMap.forcePut("Trump", "USA"); + + assertEquals("USA", capitalCountryBiMap.get("Trump")); + assertEquals("Trump", capitalCountryBiMap.inverse().get("USA")); + } + + @Test + public void whenSameKeyIsPresent_replacesAlreadyPresent() { + final BiMap capitalCountryBiMap = HashBiMap.create(); + + capitalCountryBiMap.put("New Delhi", "India"); + capitalCountryBiMap.put("Washingon, D.C.", "USA"); + capitalCountryBiMap.put("Moscow", "Russia"); + capitalCountryBiMap.put("Washingon, D.C.", "HongKong"); + + assertEquals("HongKong", capitalCountryBiMap.get("Washingon, D.C.")); + } + + @Test + public void whenUsingImmutableBiMap_allowsPutSuccessfully() { + final BiMap capitalCountryBiMap = new ImmutableBiMap.Builder().put("New Delhi", "India").put("Washingon, D.C.", "USA").put("Moscow", "Russia").build(); + + assertEquals("USA", capitalCountryBiMap.get("Washingon, D.C.")); + } + + @Test(expected = UnsupportedOperationException.class) + public void whenUsingImmutableBiMap_doesntAllowRemove() { + final BiMap capitalCountryBiMap = new ImmutableBiMap.Builder().put("New Delhi", "India").put("Washingon, D.C.", "USA").put("Moscow", "Russia").build(); + + capitalCountryBiMap.remove("New Delhi"); + } + + @Test(expected = UnsupportedOperationException.class) + public void whenUsingImmutableBiMap_doesntAllowPut() { + final BiMap capitalCountryBiMap = new ImmutableBiMap.Builder().put("New Delhi", "India").put("Washingon, D.C.", "USA").put("Moscow", "Russia").build(); + + capitalCountryBiMap.put("New York", "USA"); + } + + private enum Operation { + ADD, SUBTRACT, MULTIPLY, DIVIDE + } + + @Test + public void whenUsingEnumAsKeyInMap_replacesAlreadyPresent() { + final BiMap operationStringBiMap = EnumHashBiMap.create(Operation.class); + + operationStringBiMap.put(Operation.ADD, "Add"); + operationStringBiMap.put(Operation.SUBTRACT, "Subtract"); + operationStringBiMap.put(Operation.MULTIPLY, "Multiply"); + operationStringBiMap.put(Operation.DIVIDE, "Divide"); + + assertEquals("Divide", operationStringBiMap.get(Operation.DIVIDE)); + } +} \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/ImmutableMapUnitTest.java b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/ImmutableMapUnitTest.java new file mode 100644 index 0000000000..d308aac7eb --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/ImmutableMapUnitTest.java @@ -0,0 +1,84 @@ +package com.baeldung.map; + +import com.google.common.collect.ImmutableMap; +import org.junit.jupiter.api.Test; + +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; + +import static org.junit.jupiter.api.Assertions.*; + + +public class ImmutableMapUnitTest { + + @Test + public void whenCollectionsUnModifiableMapMethod_thenOriginalCollectionChangesReflectInUnmodifiableMap() { + + Map mutableMap = new HashMap<>(); + mutableMap.put("USA", "North America"); + + Map unmodifiableMap = Collections.unmodifiableMap(mutableMap); + assertThrows(UnsupportedOperationException.class, () -> unmodifiableMap.put("Canada", "North America")); + + mutableMap.remove("USA"); + assertFalse(unmodifiableMap.containsKey("USA")); + + mutableMap.put("Mexico", "North America"); + assertTrue(unmodifiableMap.containsKey("Mexico")); + } + + @Test + @SuppressWarnings("deprecation") + public void whenGuavaImmutableMapFromCopyOfMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() { + + Map mutableMap = new HashMap<>(); + mutableMap.put("USA", "North America"); + + ImmutableMap immutableMap = ImmutableMap.copyOf(mutableMap); + assertTrue(immutableMap.containsKey("USA")); + + assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America")); + + mutableMap.remove("USA"); + assertTrue(immutableMap.containsKey("USA")); + + mutableMap.put("Mexico", "North America"); + assertFalse(immutableMap.containsKey("Mexico")); + } + + @Test + @SuppressWarnings("deprecation") + public void whenGuavaImmutableMapFromBuilderMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() { + + Map mutableMap = new HashMap<>(); + mutableMap.put("USA", "North America"); + + ImmutableMap immutableMap = ImmutableMap.builder() + .putAll(mutableMap) + .put("Costa Rica", "North America") + .build(); + assertTrue(immutableMap.containsKey("USA")); + assertTrue(immutableMap.containsKey("Costa Rica")); + + assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America")); + + mutableMap.remove("USA"); + assertTrue(immutableMap.containsKey("USA")); + + mutableMap.put("Mexico", "North America"); + assertFalse(immutableMap.containsKey("Mexico")); + } + + @Test + @SuppressWarnings("deprecation") + public void whenGuavaImmutableMapFromOfMethod_thenOriginalCollectionChangesDoNotReflectInImmutableMap() { + + ImmutableMap immutableMap = ImmutableMap.of("USA", "North America", "Costa Rica", "North America"); + assertTrue(immutableMap.containsKey("USA")); + assertTrue(immutableMap.containsKey("Costa Rica")); + + assertThrows(UnsupportedOperationException.class, () -> immutableMap.put("Canada", "North America")); + } + +} diff --git a/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/KeyCheckUnitTest.java b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/KeyCheckUnitTest.java new file mode 100644 index 0000000000..dbad2e5b5e --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/KeyCheckUnitTest.java @@ -0,0 +1,27 @@ +package com.baeldung.map; + +import org.junit.Test; + +import java.util.Collections; +import java.util.Map; + +import static org.junit.Assert.*; + +public class KeyCheckUnitTest { + + @Test + public void whenKeyIsPresent_thenContainsKeyReturnsTrue() { + Map map = Collections.singletonMap("key", "value"); + + assertTrue(map.containsKey("key")); + assertFalse(map.containsKey("missing")); + } + + @Test + public void whenKeyHasNullValue_thenGetStillWorks() { + Map map = Collections.singletonMap("nothing", null); + + assertTrue(map.containsKey("nothing")); + assertNull(map.get("nothing")); + } +} \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapMultipleValuesUnitTest.java b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapMultipleValuesUnitTest.java new file mode 100644 index 0000000000..721b48ea7b --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapMultipleValuesUnitTest.java @@ -0,0 +1,119 @@ +package com.baeldung.map; + +import com.google.common.collect.ArrayListMultimap; +import com.google.common.collect.LinkedHashMultimap; +import com.google.common.collect.Multimap; +import com.google.common.collect.TreeMultimap; +import org.apache.commons.collections4.MultiMap; +import org.apache.commons.collections4.MultiMapUtils; +import org.apache.commons.collections4.MultiValuedMap; +import org.apache.commons.collections4.map.MultiValueMap; +import org.apache.commons.collections4.multimap.ArrayListValuedHashMap; +import org.apache.commons.collections4.multimap.HashSetValuedHashMap; +import org.junit.Test; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.*; + +import static org.assertj.core.api.Assertions.assertThat; + +public class MapMultipleValuesUnitTest { + private static final Logger LOG = LoggerFactory.getLogger(MapMultipleValuesUnitTest.class); + + @Test + public void givenHashMap_whenPuttingTwice_thenReturningFirstValue() { + Map map = new HashMap<>(); + assertThat(map.put("key1", "value1")).isEqualTo(null); + assertThat(map.put("key1", "value2")).isEqualTo("value1"); + assertThat(map.get("key1")).isEqualTo("value2"); + } + + @Test + public void givenCollectionAsValue_whenPuttingTwice_thenReturningCollection() { + Map> map = new HashMap<>(); + List list = new ArrayList<>(); + map.put("key1", list); + map.get("key1").add("value1"); + map.get("key1").add("value2"); + assertThat(map.get("key1").get(0)).isEqualTo("value1"); + assertThat(map.get("key1").get(1)).isEqualTo("value2"); + } + + @Test + public void givenCollectionAsValueAndJava8_whenPuttingTwice_thenReturningCollection() { + Map> map = new HashMap<>(); + map.computeIfAbsent("key1", k -> new ArrayList<>()).add("value1"); + map.computeIfAbsent("key1", k -> new ArrayList<>()).add("value2"); + assertThat(map.get("key1").get(0)).isEqualTo("value1"); + assertThat(map.get("key1").get(1)).isEqualTo("value2"); + } + + @Test + public void givenMultiValueMap_whenPuttingTwice_thenReturningValues() { + MultiMap map = new MultiValueMap<>(); + map.put("key1", "value1"); + map.put("key1", "value2"); + assertThat((Collection) map.get("key1")) + .contains("value1", "value2"); + } + + @Test + public void givenArrayListValuedHashMap_whenPuttingDoubleValues_thenReturningAllValues() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("key1", "value1"); + map.put("key1", "value2"); + map.put("key1", "value2"); + assertThat((Collection) map.get("key1")) + .containsExactly("value1", "value2", "value2"); + } + + @Test + public void givenHashSetValuedHashMap_whenPuttingTwiceTheSame_thenReturningOneValue() { + MultiValuedMap map = new HashSetValuedHashMap<>(); + map.put("key1", "value1"); + map.put("key1", "value1"); + assertThat((Collection) map.get("key1")) + .containsExactly("value1"); + } + + @Test(expected = UnsupportedOperationException.class) + public void givenUnmodifiableMultiValuedMap_whenInserting_thenThrowingException() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("key1", "value1"); + map.put("key1", "value2"); + MultiValuedMap immutableMap = + MultiMapUtils.unmodifiableMultiValuedMap(map); + immutableMap.put("key1", "value3"); + } + + @Test + public void givenArrayListMultiMap_whenInserting_thenCorrectOutput() { + Multimap map = ArrayListMultimap.create(); + map.put("key1", "value2"); + map.put("key1", "value1"); + assertThat((Collection) map.get("key1")) + .containsExactly("value2", "value1"); + } + + @Test + public void givenLinkedHashMultiMap_whenInserting_thenReturningValuesInInsertionOrder() { + Multimap map = LinkedHashMultimap.create(); + map.put("key1", "value3"); + map.put("key1", "value1"); + map.put("key1", "value2"); + assertThat((Collection) map.get("key1")) + .containsExactly("value3", "value1", "value2"); + } + + @Test + public void givenTreeMultimap_whenInserting_thenReturningValuesInNaturalOrder() { + Multimap map = TreeMultimap.create(); + map.put("key1", "value3"); + map.put("key1", "value1"); + map.put("key1", "value2"); + assertThat((Collection) map.get("key1")) + .containsExactly("value1", "value2", "value3"); + } + +} \ No newline at end of file diff --git a/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapUnitTest.java b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapUnitTest.java new file mode 100644 index 0000000000..eaf68ccba5 --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapUnitTest.java @@ -0,0 +1,336 @@ +package com.baeldung.map; + +import org.junit.Test; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.*; +import java.util.Map.Entry; + +import static org.junit.Assert.*; + +public class MapUnitTest { + private static final Logger LOG = LoggerFactory.getLogger(MapUnitTest.class); + + + @Test + public void givenHashMap_whenRetrievesKeyset_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Set keys = map.keySet(); + + assertEquals(2, keys.size()); + assertTrue(keys.contains("name")); + assertTrue(keys.contains("type")); + } + + @Test + public void givenHashMap_whenRetrievesValues_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Collection values = map.values(); + + assertEquals(2, values.size()); + assertTrue(values.contains("baeldung")); + assertTrue(values.contains("blog")); + } + + @Test + public void givenHashMap_whenRetrievesEntries_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Set> entries = map.entrySet(); + + assertEquals(2, entries.size()); + for (Entry e : entries) { + String key = e.getKey(); + String val = e.getValue(); + assertTrue(key.equals("name") || key.equals("type")); + assertTrue(val.equals("baeldung") || val.equals("blog")); + } + } + + @Test + public void givenKeySet_whenChangeReflectsInMap_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + assertEquals(2, map.size()); + + Set keys = map.keySet(); + + keys.remove("name"); + assertEquals(1, map.size()); + } + + @Test(expected = ConcurrentModificationException.class) + public void givenIterator_whenFailsFastOnModification_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Set keys = map.keySet(); + Iterator it = keys.iterator(); + map.remove("type"); + while (it.hasNext()) { + String key = it.next(); + } + } + + public void givenIterator_whenRemoveWorks_thenCorrect() { + Map map = new HashMap<>(); + map.put("name", "baeldung"); + map.put("type", "blog"); + + Set keys = map.keySet(); + Iterator it = keys.iterator(); + while (it.hasNext()) { + it.next(); + it.remove(); + } + assertEquals(0, map.size()); + } + + @Test + public void whenHashCodeIsCalledOnPut_thenCorrect() { + MyKey key = new MyKey(1, "name"); + Map map = new HashMap<>(); + map.put(key, "val"); + } + + @Test + public void whenHashCodeIsCalledOnGet_thenCorrect() { + MyKey key = new MyKey(1, "name"); + Map map = new HashMap<>(); + map.put(key, "val"); + map.get(key); + } + + @Test + public void whenGetWorks_thenCorrect() { + Map map = new HashMap<>(); + map.put("key", "val"); + + String val = map.get("key"); + + assertEquals("val", val); + } + + @Test + public void givenNewKey_whenPutReturnsNull_thenCorrect() { + Map map = new HashMap<>(); + + String rtnVal = map.put("key1", "val1"); + + assertNull(rtnVal); + } + + @Test + public void givenUnmappedKey_whenGetReturnsNull_thenCorrect() { + Map map = new HashMap<>(); + + String rtnVal = map.get("key1"); + + assertNull(rtnVal); + } + + @Test + public void givenNullVal_whenPutReturnsNull_thenCorrect() { + Map map = new HashMap<>(); + + String rtnVal = map.put("key1", null); + + assertNull(rtnVal); + } + + @Test + public void givenNullKeyAndVal_whenAccepts_thenCorrect() { + Map map = new HashMap<>(); + + map.put(null, null); + } + + @Test + public void givenNullVal_whenRetrieves_thenCorrect() { + Map map = new HashMap<>(); + map.put("key", null); + + String val = map.get("key"); + + assertNull(val); + } + + @Test + public void whenContainsDistinguishesNullValues_thenCorrect() { + Map map = new HashMap<>(); + + String val1 = map.get("key"); + boolean valPresent = map.containsKey("key"); + + assertNull(val1); + assertFalse(valPresent); + + map.put("key", null); + String val = map.get("key"); + valPresent = map.containsKey("key"); + + assertNull(val); + assertTrue(valPresent); + + } + + @Test + public void whenPutReturnsPrevValue_thenCorrect() { + Map map = new HashMap<>(); + map.put("key1", "val1"); + String rtnVal = map.put("key1", "val2"); + + assertEquals("val1", rtnVal); + } + + @Test + public void whenCallsEqualsOnCollision_thenCorrect() { + HashMap map = new HashMap<>(); + MyKey k1 = new MyKey(1, "firstKey"); + MyKey k2 = new MyKey(2, "secondKey"); + MyKey k3 = new MyKey(2, "thirdKey"); + + LOG.debug("storing value for k1"); + map.put(k1, "firstValue"); + + LOG.debug("storing value for k2"); + map.put(k2, "secondValue"); + + LOG.debug("storing value for k3"); + map.put(k3, "thirdValue"); + + LOG.debug("retrieving value for k1"); + String v1 = map.get(k1); + + LOG.debug("retrieving value for k2"); + String v2 = map.get(k2); + + LOG.debug("retrieving value for k3"); + String v3 = map.get(k3); + + assertEquals("firstValue", v1); + assertEquals("secondValue", v2); + assertEquals("thirdValue", v3); + + } + + @Test + public void givenLinkedHashMap_whenGetsOrderedKeyset_thenCorrect() { + LinkedHashMap map = new LinkedHashMap<>(); + map.put(1, null); + map.put(2, null); + map.put(3, null); + map.put(4, null); + map.put(5, null); + Set keys = map.keySet(); + Integer[] arr = keys.toArray(new Integer[0]); + for (int i = 0; i < arr.length; i++) { + assertEquals(new Integer(i + 1), arr[i]); + + } + } + + @Test + public void givenLinkedHashMap_whenAccessOrderWorks_thenCorrect() { + LinkedHashMap map = new LinkedHashMap<>(16, .75f, true); + map.put(1, null); + map.put(2, null); + map.put(3, null); + map.put(4, null); + map.put(5, null); + Set keys = map.keySet(); + assertEquals("[1, 2, 3, 4, 5]", keys.toString()); + map.get(4); + assertEquals("[1, 2, 3, 5, 4]", keys.toString()); + map.get(1); + assertEquals("[2, 3, 5, 4, 1]", keys.toString()); + map.get(3); + assertEquals("[2, 5, 4, 1, 3]", keys.toString()); + } + + @Test + public void givenLinkedHashMap_whenRemovesEldestEntry_thenCorrect() { + LinkedHashMap map = new MyLinkedHashMap<>(16, .75f, true); + map.put(1, null); + map.put(2, null); + map.put(3, null); + map.put(4, null); + map.put(5, null); + Set keys = map.keySet(); + assertEquals("[1, 2, 3, 4, 5]", keys.toString()); + map.put(6, null); + assertEquals("[2, 3, 4, 5, 6]", keys.toString()); + map.put(7, null); + assertEquals("[3, 4, 5, 6, 7]", keys.toString()); + map.put(8, null); + assertEquals("[4, 5, 6, 7, 8]", keys.toString()); + } + + @Test + public void givenTreeMap_whenOrdersEntriesNaturally_thenCorrect() { + TreeMap map = new TreeMap<>(); + map.put(3, "val"); + map.put(2, "val"); + map.put(1, "val"); + map.put(5, "val"); + map.put(4, "val"); + assertEquals("[1, 2, 3, 4, 5]", map.keySet().toString()); + } + + @Test + public void givenTreeMap_whenOrdersEntriesNaturally_thenCorrect2() { + TreeMap map = new TreeMap<>(); + map.put("c", "val"); + map.put("b", "val"); + map.put("a", "val"); + map.put("e", "val"); + map.put("d", "val"); + + assertEquals("[a, b, c, d, e]", map.keySet().toString()); + } + + @Test + public void givenTreeMap_whenOrdersEntriesByComparator_thenCorrect() { + TreeMap map = new TreeMap<>(Comparator.reverseOrder()); + map.put(3, "val"); + map.put(2, "val"); + map.put(1, "val"); + map.put(5, "val"); + map.put(4, "val"); + + assertEquals("[5, 4, 3, 2, 1]", map.keySet().toString()); + } + + @Test + public void givenTreeMap_whenPerformsQueries_thenCorrect() { + TreeMap map = new TreeMap<>(); + map.put(3, "val"); + map.put(2, "val"); + map.put(1, "val"); + map.put(5, "val"); + map.put(4, "val"); + + Integer highestKey = map.lastKey(); + Integer lowestKey = map.firstKey(); + Set keysLessThan3 = map.headMap(3).keySet(); + Set keysGreaterThanEqTo3 = map.tailMap(3).keySet(); + + assertEquals(new Integer(5), highestKey); + assertEquals(new Integer(1), lowestKey); + assertEquals("[1, 2]", keysLessThan3.toString()); + assertEquals("[3, 4, 5]", keysGreaterThanEqTo3.toString()); + } + +} diff --git a/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapUtilUnitTest.java b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapUtilUnitTest.java new file mode 100644 index 0000000000..f8e4c8fd8a --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MapUtilUnitTest.java @@ -0,0 +1,103 @@ +/** + * + */ +package com.baeldung.map; + +import com.google.common.collect.HashBiMap; +import org.apache.commons.collections4.BidiMap; +import org.apache.commons.collections4.bidimap.DualHashBidiMap; +import org.junit.Test; + +import java.util.Arrays; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Map; +import java.util.stream.Collectors; + +import static org.junit.Assert.assertEquals; + +/** + * @author swpraman + * + */ +public class MapUtilUnitTest { + + + @Test + public void whenUsingImperativeWayForSingleKey_shouldReturnSingleKey() { + Map capitalCountryMap = new HashMap<>(); + capitalCountryMap.put("Tokyo", "Japan"); + capitalCountryMap.put("New Delhi", "India"); + assertEquals("New Delhi", MapUtil.getKey(capitalCountryMap, "India")); + } + + @Test + public void whenUsingImperativeWayForAllKeys_shouldReturnAllKeys() { + Map capitalCountryMap = new HashMap<>(); + capitalCountryMap.put("Tokyo", "Japan"); + capitalCountryMap.put("Berlin", "Germany"); + capitalCountryMap.put("Cape Town", "South Africa"); + capitalCountryMap.put("Pretoria", "South Africa"); + capitalCountryMap.put("Bloemfontein", "South Africa"); + + assertEquals(new HashSet(Arrays.asList( + new String[] {"Cape Town", "Pretoria", "Bloemfontein"})), + MapUtil.getKeys(capitalCountryMap, "South Africa")); + } + + @Test + public void whenUsingFunctionalWayForSingleKey_shouldReturnSingleKey() { + Map capitalCountryMap = new HashMap<>(); + capitalCountryMap.put("Tokyo", "Japan"); + capitalCountryMap.put("Berlin", "Germany"); + assertEquals("Berlin", MapUtil.keys(capitalCountryMap, "Germany").findFirst().get()); + } + + @Test + public void whenUsingFunctionalWayForAllKeys_shouldReturnAllKeys() { + Map capitalCountryMap = new HashMap<>(); + capitalCountryMap.put("Tokyo", "Japan"); + capitalCountryMap.put("Berlin", "Germany"); + capitalCountryMap.put("Cape Town", "South Africa"); + capitalCountryMap.put("Pretoria", "South Africa"); + capitalCountryMap.put("Bloemfontein", "South Africa"); + assertEquals(new HashSet(Arrays.asList( + new String[] {"Cape Town", "Pretoria", "Bloemfontein"})), + MapUtil.keys(capitalCountryMap, "South Africa").collect(Collectors.toSet())); + } + + @Test + public void whenUsingBidiMap_shouldReturnKey() { + BidiMap capitalCountryMap = new DualHashBidiMap(); + capitalCountryMap.put("Berlin", "Germany"); + capitalCountryMap.put("Cape Town", "South Africa"); + assertEquals("Berlin", capitalCountryMap.getKey("Germany")); + } + + @Test + public void whenUsingBidiMapAddDuplicateValue_shouldRemoveOldEntry() { + BidiMap capitalCountryMap = new DualHashBidiMap(); + capitalCountryMap.put("Berlin", "Germany"); + capitalCountryMap.put("Cape Town", "South Africa"); + capitalCountryMap.put("Pretoria", "South Africa"); + assertEquals("Pretoria", capitalCountryMap.getKey("South Africa")); + } + + @Test + public void whenUsingBiMap_shouldReturnKey() { + HashBiMap capitalCountryMap = HashBiMap.create(); + capitalCountryMap.put("Berlin", "Germany"); + capitalCountryMap.put("Cape Town", "South Africa"); + assertEquals("Berlin", capitalCountryMap.inverse().get("Germany")); + } + + @Test(expected=IllegalArgumentException.class) + public void whenUsingBiMapAddDuplicateValue_shouldThrowException() { + HashBiMap capitalCountryMap = HashBiMap.create(); + capitalCountryMap.put("Berlin", "Germany"); + capitalCountryMap.put("Cape Town", "South Africa"); + capitalCountryMap.put("Pretoria", "South Africa"); + assertEquals("Berlin", capitalCountryMap.inverse().get("Germany")); + } + +} diff --git a/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MultiValuedMapUnitTest.java b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MultiValuedMapUnitTest.java new file mode 100644 index 0000000000..686c1cef87 --- /dev/null +++ b/core-java-modules/core-java-collections-maps/src/test/java/com/baeldung/map/MultiValuedMapUnitTest.java @@ -0,0 +1,227 @@ +package com.baeldung.map; + +import org.apache.commons.collections4.MultiMapUtils; +import org.apache.commons.collections4.MultiSet; +import org.apache.commons.collections4.MultiValuedMap; +import org.apache.commons.collections4.multimap.ArrayListValuedHashMap; +import org.apache.commons.collections4.multimap.HashSetValuedHashMap; +import org.junit.Test; + +import java.util.Arrays; +import java.util.Collection; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Set; + +import static org.assertj.core.api.Assertions.assertThat; +import static org.junit.Assert.assertTrue; +import static org.junit.jupiter.api.Assertions.assertEquals; +import static org.junit.jupiter.api.Assertions.assertFalse; + +public class MultiValuedMapUnitTest { + + @Test + public void givenMultiValuesMap_whenPuttingMultipleValuesUsingPutMethod_thenReturningAllValues() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + + map.put("fruits", "apple"); + map.put("fruits", "orange"); + + assertThat((Collection) map.get("fruits")).containsExactly("apple", "orange"); + + } + + @Test + public void givenMultiValuesMap_whenPuttingMultipleValuesUsingPutAllMethod_thenReturningAllValues() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + + map.putAll("vehicles", Arrays.asList("car", "bike")); + + assertThat((Collection) map.get("vehicles")).containsExactly("car", "bike"); + + } + + @Test + public void givenMultiValuesMap_whenGettingValueUsingGetMethod_thenReturningValue() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + + map.put("fruits", "apple"); + + assertThat((Collection) map.get("fruits")).containsExactly("apple"); + } + + @Test + public void givenMultiValuesMap_whenUsingEntriesMethod_thenReturningMappings() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + + Collection> entries = (Collection>) map.entries(); + + for(Map.Entry entry : entries) { + assertThat(entry.getKey()).contains("fruits"); + assertTrue(entry.getValue().equals("apple") || entry.getValue().equals("orange") ); + } + } + + @Test + public void givenMultiValuesMap_whenUsingKeysMethod_thenReturningAllKeys() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + + MultiSet keys = map.keys(); + + assertThat((keys)).contains("fruits", "vehicles"); + + } + + @Test + public void givenMultiValuesMap_whenUsingKeySetMethod_thenReturningAllKeys() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + + Set keys = map.keySet(); + + assertThat(keys).contains("fruits", "vehicles"); + + } + + @Test + public void givenMultiValuesMap_whenUsingValuesMethod_thenReturningAllValues() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + + assertThat(((Collection) map.values())).contains("apple", "orange", "car", "bike"); + } + + @Test + public void givenMultiValuesMap_whenUsingRemoveMethod_thenReturningUpdatedMap() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + assertThat(((Collection) map.values())).contains("apple", "orange", "car", "bike"); + + map.remove("fruits"); + + assertThat(((Collection) map.values())).contains("car", "bike"); + + } + + @Test + public void givenMultiValuesMap_whenUsingRemoveMappingMethod_thenReturningUpdatedMapAfterMappingRemoved() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + assertThat(((Collection) map.values())).contains("apple", "orange", "car", "bike"); + + map.removeMapping("fruits", "apple"); + + assertThat(((Collection) map.values())).contains("orange", "car", "bike"); + } + + @Test + public void givenMultiValuesMap_whenUsingClearMethod_thenReturningEmptyMap() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + assertThat(((Collection) map.values())).contains("apple", "orange", "car", "bike"); + + map.clear(); + + assertTrue(map.isEmpty()); + } + + @Test + public void givenMultiValuesMap_whenUsingContainsKeyMethod_thenReturningTrue() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + + assertTrue(map.containsKey("fruits")); + } + + @Test + public void givenMultiValuesMap_whenUsingContainsValueMethod_thenReturningTrue() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + + assertTrue(map.containsValue("orange")); + } + + @Test + public void givenMultiValuesMap_whenUsingIsEmptyMethod_thenReturningFalse() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + + assertFalse(map.isEmpty()); + } + + @Test + public void givenMultiValuesMap_whenUsingSizeMethod_thenReturningElementCount() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("vehicles", "car"); + map.put("vehicles", "bike"); + + assertEquals(4, map.size()); + } + + @Test + public void givenArrayListValuedHashMap_whenPuttingDoubleValues_thenReturningAllValues() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + map.put("fruits", "orange"); + + assertThat((Collection) map.get("fruits")).containsExactly("apple", "orange", "orange"); + } + + @Test + public void givenHashSetValuedHashMap_whenPuttingTwiceTheSame_thenReturningOneValue() { + MultiValuedMap map = new HashSetValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "apple"); + + assertThat((Collection) map.get("fruits")).containsExactly("apple"); + } + + @Test(expected = UnsupportedOperationException.class) + public void givenUnmodifiableMultiValuedMap_whenInserting_thenThrowingException() { + MultiValuedMap map = new ArrayListValuedHashMap<>(); + map.put("fruits", "apple"); + map.put("fruits", "orange"); + MultiValuedMap immutableMap = MultiMapUtils.unmodifiableMultiValuedMap(map); + + immutableMap.put("fruits", "banana"); + + } + + +} diff --git a/core-java-modules/pom.xml b/core-java-modules/pom.xml index ebdb11925b..3fc978a68c 100644 --- a/core-java-modules/pom.xml +++ b/core-java-modules/pom.xml @@ -42,6 +42,9 @@ core-java-collections-list core-java-collections-list-2 core-java-collections-list-3 + core-java-collections-maps + core-java-collections-maps-2 + core-java-collections-maps-3 core-java-concurrency-2