[BAEL-9550] - Moved articles and codes from core-java-collections module to java-collections-convversions and java-collections-maps module
This commit is contained in:
amit2103
@@ -0,0 +1,52 @@
|
||||
package com.baeldung.convertcollectiontoarraylist;
|
||||
|
||||
/**
|
||||
* This POJO is the element type of our collection. It has a deepCopy() method.
|
||||
*
|
||||
* @author chris
|
||||
*/
|
||||
public class Foo {
|
||||
|
||||
private int id;
|
||||
private String name;
|
||||
private Foo parent;
|
||||
|
||||
public Foo() {
|
||||
}
|
||||
|
||||
public Foo(int id, String name, Foo parent) {
|
||||
this.id = id;
|
||||
this.name = name;
|
||||
this.parent = parent;
|
||||
}
|
||||
|
||||
public int getId() {
|
||||
return id;
|
||||
}
|
||||
|
||||
public void setId(int id) {
|
||||
this.id = id;
|
||||
}
|
||||
|
||||
public String getName() {
|
||||
return name;
|
||||
}
|
||||
|
||||
public void setName(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
|
||||
public Foo getParent() {
|
||||
return parent;
|
||||
}
|
||||
|
||||
public void setParent(Foo parent) {
|
||||
this.parent = parent;
|
||||
}
|
||||
|
||||
public Foo deepCopy() {
|
||||
return new Foo(
|
||||
this.id, this.name, this.parent != null ? this.parent.deepCopy() : null);
|
||||
}
|
||||
|
||||
}
|
||||
@@ -0,0 +1,27 @@
|
||||
package com.baeldung.convertlisttomap;
|
||||
|
||||
public class Animal {
|
||||
private int id;
|
||||
private String name;
|
||||
|
||||
public Animal(int id, String name) {
|
||||
this.id = id;
|
||||
this.setName(name);
|
||||
}
|
||||
|
||||
public int getId() {
|
||||
return id;
|
||||
}
|
||||
|
||||
public void setId(int id) {
|
||||
this.id = id;
|
||||
}
|
||||
|
||||
public String getName() {
|
||||
return name;
|
||||
}
|
||||
|
||||
public void setName(String name) {
|
||||
this.name = name;
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,42 @@
|
||||
package com.baeldung.convertlisttomap;
|
||||
|
||||
import com.google.common.collect.Maps;
|
||||
import org.apache.commons.collections4.MapUtils;
|
||||
|
||||
import java.util.HashMap;
|
||||
import java.util.List;
|
||||
import java.util.Map;
|
||||
import java.util.stream.Collectors;
|
||||
|
||||
public class ConvertListToMapService {
|
||||
|
||||
public Map<Integer, Animal> convertListBeforeJava8(List<Animal> list) {
|
||||
|
||||
Map<Integer, Animal> map = new HashMap<>();
|
||||
|
||||
for (Animal animal : list) {
|
||||
map.put(animal.getId(), animal);
|
||||
}
|
||||
return map;
|
||||
}
|
||||
|
||||
public Map<Integer, Animal> convertListAfterJava8(List<Animal> list) {
|
||||
Map<Integer, Animal> map = list.stream().collect(Collectors.toMap(Animal::getId, animal -> animal));
|
||||
return map;
|
||||
}
|
||||
|
||||
public Map<Integer, Animal> convertListWithGuava(List<Animal> list) {
|
||||
|
||||
Map<Integer, Animal> map = Maps.uniqueIndex(list, Animal::getId);
|
||||
return map;
|
||||
}
|
||||
|
||||
public Map<Integer, Animal> convertListWithApacheCommons(List<Animal> list) {
|
||||
|
||||
Map<Integer, Animal> map = new HashMap<>();
|
||||
|
||||
MapUtils.populateMap(map, list, Animal::getId);
|
||||
|
||||
return map;
|
||||
}
|
||||
}
|
||||
13
java-collections-conversions/src/main/resources/logback.xml
Normal file
13
java-collections-conversions/src/main/resources/logback.xml
Normal file
@@ -0,0 +1,13 @@
|
||||
<?xml version="1.0" encoding="UTF-8"?>
|
||||
<configuration>
|
||||
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
|
||||
<encoder>
|
||||
<pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
|
||||
</pattern>
|
||||
</encoder>
|
||||
</appender>
|
||||
|
||||
<root level="INFO">
|
||||
<appender-ref ref="STDOUT" />
|
||||
</root>
|
||||
</configuration>
|
||||
@@ -0,0 +1,148 @@
|
||||
package com.baeldung.convertcollectiontoarraylist;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.Collection;
|
||||
import java.util.Comparator;
|
||||
import java.util.HashSet;
|
||||
import java.util.Iterator;
|
||||
import static java.util.stream.Collectors.toCollection;
|
||||
import org.junit.BeforeClass;
|
||||
import org.junit.Test;
|
||||
import static org.junit.Assert.*;
|
||||
|
||||
/**
|
||||
*
|
||||
* @author chris
|
||||
*/
|
||||
public class FooUnitTest {
|
||||
private static Collection<Foo> srcCollection = new HashSet<>();
|
||||
|
||||
public FooUnitTest() {
|
||||
}
|
||||
|
||||
@BeforeClass
|
||||
public static void setUpClass() {
|
||||
int i = 0;
|
||||
Foo john = new Foo(i++, "John", null);
|
||||
Foo mary = new Foo(i++, "Mary", null);
|
||||
Foo sam = new Foo(i++, "Sam", john);
|
||||
Foo alice = new Foo(i++, "Alice", john);
|
||||
Foo buffy = new Foo(i++, "Buffy", sam);
|
||||
srcCollection.add(john);
|
||||
srcCollection.add(mary);
|
||||
srcCollection.add(sam);
|
||||
srcCollection.add(alice);
|
||||
srcCollection.add(buffy);
|
||||
|
||||
// make sure the collection isn't sorted accidentally
|
||||
assertFalse("Oops: source collection is already sorted!", isSorted(srcCollection));
|
||||
}
|
||||
|
||||
/**
|
||||
* Section 3. Using the ArrayList Constructor
|
||||
*/
|
||||
@Test
|
||||
public void whenUsingConstructor_thenVerifyShallowCopy() {
|
||||
ArrayList<Foo> newList = new ArrayList<>(srcCollection);
|
||||
verifyShallowCopy(srcCollection, newList);
|
||||
}
|
||||
|
||||
/**
|
||||
* Section 4. Using the Streams API
|
||||
*/
|
||||
@Test
|
||||
public void whenUsingStream_thenVerifyShallowCopy() {
|
||||
ArrayList<Foo> newList = srcCollection.stream().collect(toCollection(ArrayList::new));
|
||||
|
||||
verifyShallowCopy(srcCollection, newList);
|
||||
}
|
||||
|
||||
/**
|
||||
* Section 5. Deep Copy
|
||||
*/
|
||||
@Test
|
||||
public void whenUsingDeepCopy_thenVerifyDeepCopy() {
|
||||
ArrayList<Foo> newList = srcCollection.stream()
|
||||
.map(foo -> foo.deepCopy())
|
||||
.collect(toCollection(ArrayList::new));
|
||||
|
||||
verifyDeepCopy(srcCollection, newList);
|
||||
}
|
||||
|
||||
/**
|
||||
* Section 6. Controlling the List Order
|
||||
*/
|
||||
@Test
|
||||
public void whenUsingSortedStream_thenVerifySortOrder() {
|
||||
ArrayList<Foo> newList = srcCollection.stream()
|
||||
.sorted(Comparator.comparing(Foo::getName))
|
||||
.collect(toCollection(ArrayList::new));
|
||||
|
||||
assertTrue("ArrayList is not sorted by name", isSorted(newList));
|
||||
}
|
||||
|
||||
/**
|
||||
* Verify that the contents of the two collections are the same
|
||||
* @param a
|
||||
* @param b
|
||||
*/
|
||||
private void verifyShallowCopy(Collection a, Collection b) {
|
||||
assertEquals("Collections have different lengths", a.size(), b.size());
|
||||
Iterator<Foo> iterA = a.iterator();
|
||||
Iterator<Foo> iterB = b.iterator();
|
||||
while (iterA.hasNext()) {
|
||||
// use '==' to test instance identity
|
||||
assertTrue("Foo instances differ!", iterA.next() == iterB.next());
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Verify that the contents of the two collections are the same
|
||||
* @param a
|
||||
* @param b
|
||||
*/
|
||||
private void verifyDeepCopy(Collection a, Collection b) {
|
||||
assertEquals("Collections have different lengths", a.size(), b.size());
|
||||
Iterator<Foo> iterA = a.iterator();
|
||||
Iterator<Foo> iterB = b.iterator();
|
||||
while (iterA.hasNext()) {
|
||||
Foo nextA = iterA.next();
|
||||
Foo nextB = iterB.next();
|
||||
// should not be same instance
|
||||
assertFalse("Foo instances are the same!", nextA == nextB);
|
||||
// but should have same content
|
||||
assertFalse("Foo instances have different content!", fooDiff(nextA, nextB));
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Return true if the contents of a and b differ. Test parent recursively
|
||||
* @param a
|
||||
* @param b
|
||||
* @return False if the two items are the same
|
||||
*/
|
||||
private boolean fooDiff(Foo a, Foo b) {
|
||||
if (a != null && b != null) {
|
||||
return a.getId() != b.getId()
|
||||
|| !a.getName().equals(b.getName())
|
||||
|| fooDiff(a.getParent(), b.getParent());
|
||||
}
|
||||
return !(a == null && b == null);
|
||||
}
|
||||
|
||||
/**
|
||||
* @param c collection of Foo
|
||||
* @return true if the collection is sorted by name
|
||||
*/
|
||||
private static boolean isSorted(Collection<Foo> c) {
|
||||
String prevName = null;
|
||||
for (Foo foo : c) {
|
||||
if (prevName == null || foo.getName().compareTo(prevName) > 0) {
|
||||
prevName = foo.getName();
|
||||
} else {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,68 @@
|
||||
package com.baeldung.convertlisttomap;
|
||||
|
||||
import org.junit.Before;
|
||||
import org.junit.Test;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.List;
|
||||
import java.util.Map;
|
||||
|
||||
import static org.hamcrest.MatcherAssert.assertThat;
|
||||
import static org.hamcrest.Matchers.containsInAnyOrder;
|
||||
|
||||
public class ConvertListToMapServiceUnitTest {
|
||||
List<Animal> list;
|
||||
|
||||
private ConvertListToMapService convertListService;
|
||||
|
||||
@Before
|
||||
public void init() {
|
||||
this.convertListService = new ConvertListToMapService();
|
||||
this.list = new ArrayList<>();
|
||||
|
||||
Animal cat = new Animal(1, "Cat");
|
||||
list.add(cat);
|
||||
Animal dog = new Animal(2, "Dog");
|
||||
list.add(dog);
|
||||
Animal pig = new Animal(3, "Pig");
|
||||
list.add(pig);
|
||||
Animal cow = new Animal(4, "Cow");
|
||||
list.add(cow);
|
||||
Animal goat = new Animal(5, "Goat");
|
||||
list.add(goat);
|
||||
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenConvertBeforeJava8_thenReturnMapWithTheSameElements() {
|
||||
|
||||
Map<Integer, Animal> map = convertListService.convertListBeforeJava8(list);
|
||||
|
||||
assertThat(map.values(), containsInAnyOrder(list.toArray()));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenConvertAfterJava8_thenReturnMapWithTheSameElements() {
|
||||
|
||||
Map<Integer, Animal> map = convertListService.convertListAfterJava8(list);
|
||||
|
||||
assertThat(map.values(), containsInAnyOrder(list.toArray()));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenConvertWithGuava_thenReturnMapWithTheSameElements() {
|
||||
|
||||
Map<Integer, Animal> map = convertListService.convertListWithGuava(list);
|
||||
|
||||
assertThat(map.values(), containsInAnyOrder(list.toArray()));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenAList_whenConvertWithApacheCommons_thenReturnMapWithTheSameElements() {
|
||||
|
||||
Map<Integer, Animal> map = convertListService.convertListWithApacheCommons(list);
|
||||
|
||||
assertThat(map.values(), containsInAnyOrder(list.toArray()));
|
||||
}
|
||||
|
||||
}
|
||||
@@ -0,0 +1,68 @@
|
||||
package com.baeldung.convertlisttomap;
|
||||
|
||||
import org.junit.Before;
|
||||
import org.junit.Test;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.List;
|
||||
import java.util.Map;
|
||||
|
||||
import static org.hamcrest.MatcherAssert.assertThat;
|
||||
import static org.hamcrest.Matchers.hasItem;
|
||||
import static org.hamcrest.Matchers.hasSize;
|
||||
|
||||
public class ConvertListWithDiplicatedIdToMapServiceUnitTest {
|
||||
List<Animal> duplicatedIdList;
|
||||
|
||||
private ConvertListToMapService convertListService = new ConvertListToMapService();
|
||||
|
||||
@Before
|
||||
public void init() {
|
||||
|
||||
this.duplicatedIdList = new ArrayList<>();
|
||||
|
||||
Animal cat = new Animal(1, "Cat");
|
||||
duplicatedIdList.add(cat);
|
||||
Animal dog = new Animal(2, "Dog");
|
||||
duplicatedIdList.add(dog);
|
||||
Animal pig = new Animal(3, "Pig");
|
||||
duplicatedIdList.add(pig);
|
||||
Animal cow = new Animal(4, "Cow");
|
||||
duplicatedIdList.add(cow);
|
||||
Animal goat = new Animal(4, "Goat");
|
||||
duplicatedIdList.add(goat);
|
||||
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenADupIdList_whenConvertBeforeJava8_thenReturnMapWithRewrittenElement() {
|
||||
|
||||
Map<Integer, Animal> map = convertListService.convertListBeforeJava8(duplicatedIdList);
|
||||
|
||||
assertThat(map.values(), hasSize(4));
|
||||
assertThat(map.values(), hasItem(duplicatedIdList.get(4)));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void givenADupIdList_whenConvertWithApacheCommons_thenReturnMapWithRewrittenElement() {
|
||||
|
||||
Map<Integer, Animal> map = convertListService.convertListWithApacheCommons(duplicatedIdList);
|
||||
|
||||
assertThat(map.values(), hasSize(4));
|
||||
assertThat(map.values(), hasItem(duplicatedIdList.get(4)));
|
||||
}
|
||||
|
||||
@Test(expected = IllegalStateException.class)
|
||||
public void givenADupIdList_whenConvertAfterJava8_thenException() {
|
||||
|
||||
convertListService.convertListAfterJava8(duplicatedIdList);
|
||||
}
|
||||
|
||||
@Test(expected = IllegalArgumentException.class)
|
||||
public void givenADupIdList_whenConvertWithGuava_thenException() {
|
||||
|
||||
convertListService.convertListWithGuava(duplicatedIdList);
|
||||
|
||||
}
|
||||
|
||||
}
|
||||
@@ -0,0 +1,187 @@
|
||||
package org.baeldung.java.collections;
|
||||
|
||||
import java.util.ArrayList;
|
||||
import java.util.Arrays;
|
||||
import java.util.Collection;
|
||||
import java.util.Collections;
|
||||
import java.util.HashMap;
|
||||
import java.util.HashSet;
|
||||
import java.util.List;
|
||||
import java.util.Map;
|
||||
import java.util.Set;
|
||||
|
||||
import org.apache.commons.collections4.CollectionUtils;
|
||||
import org.apache.commons.lang3.ArrayUtils;
|
||||
import org.junit.Test;
|
||||
|
||||
import com.google.common.collect.Lists;
|
||||
import com.google.common.collect.Sets;
|
||||
import com.google.common.primitives.Ints;
|
||||
|
||||
@SuppressWarnings("unused")
|
||||
public class JavaCollectionConversionUnitTest {
|
||||
|
||||
// List -> array; array -> List
|
||||
|
||||
@Test
|
||||
public final void givenUsingCoreJava_whenArrayConvertedToList_thenCorrect() {
|
||||
final Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };
|
||||
final List<Integer> targetList = Arrays.asList(sourceArray);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCoreJava_whenListConvertedToArray_thenCorrect() {
|
||||
final List<Integer> sourceList = Arrays.asList(0, 1, 2, 3, 4, 5);
|
||||
final Integer[] targetArray = sourceList.toArray(new Integer[sourceList.size()]);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingGuava_whenArrayConvertedToList_thenCorrect() {
|
||||
final Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };
|
||||
final List<Integer> targetList = Lists.newArrayList(sourceArray);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingGuava_whenListConvertedToArray_thenCorrect() {
|
||||
final List<Integer> sourceList = Lists.newArrayList(0, 1, 2, 3, 4, 5);
|
||||
final int[] targetArray = Ints.toArray(sourceList);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCommonsCollections_whenArrayConvertedToList_thenCorrect() {
|
||||
final Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };
|
||||
final List<Integer> targetList = new ArrayList<>(6);
|
||||
CollectionUtils.addAll(targetList, sourceArray);
|
||||
}
|
||||
|
||||
// Set -> array; array -> Set
|
||||
|
||||
@Test
|
||||
public final void givenUsingCoreJavaV1_whenArrayConvertedToSet_thenCorrect() {
|
||||
final Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };
|
||||
final Set<Integer> targetSet = new HashSet<Integer>(Arrays.asList(sourceArray));
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCoreJavaV2_whenArrayConvertedToSet_thenCorrect() {
|
||||
final Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };
|
||||
final Set<Integer> targetSet = new HashSet<Integer>();
|
||||
Collections.addAll(targetSet, sourceArray);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCoreJava_whenSetConvertedToArray_thenCorrect() {
|
||||
final Set<Integer> sourceSet = Sets.newHashSet(0, 1, 2, 3, 4, 5);
|
||||
final Integer[] targetArray = sourceSet.toArray(new Integer[sourceSet.size()]);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingGuava_whenArrayConvertedToSet_thenCorrect() {
|
||||
final Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };
|
||||
final Set<Integer> targetSet = Sets.newHashSet(sourceArray);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingGuava_whenSetConvertedToArray_thenCorrect() {
|
||||
final Set<Integer> sourceSet = Sets.newHashSet(0, 1, 2, 3, 4, 5);
|
||||
final int[] targetArray = Ints.toArray(sourceSet);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCommonsCollections_whenArrayConvertedToSet_thenCorrect() {
|
||||
final Integer[] sourceArray = { 0, 1, 2, 3, 4, 5 };
|
||||
final Set<Integer> targetSet = new HashSet<>(6);
|
||||
CollectionUtils.addAll(targetSet, sourceArray);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCommonsCollections_whenSetConvertedToArray_thenCorrect() {
|
||||
final Set<Integer> sourceSet = Sets.newHashSet(0, 1, 2, 3, 4, 5);
|
||||
final Integer[] targetArray = sourceSet.toArray(new Integer[sourceSet.size()]);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCommonsCollections_whenSetConvertedToArrayOfPrimitives_thenCorrect() {
|
||||
final Set<Integer> sourceSet = Sets.newHashSet(0, 1, 2, 3, 4, 5);
|
||||
final Integer[] targetArray = sourceSet.toArray(new Integer[sourceSet.size()]);
|
||||
final int[] primitiveTargetArray = ArrayUtils.toPrimitive(targetArray);
|
||||
}
|
||||
|
||||
// Set -> List; List -> Set
|
||||
|
||||
public final void givenUsingCoreJava_whenSetConvertedToList_thenCorrect() {
|
||||
final Set<Integer> sourceSet = Sets.newHashSet(0, 1, 2, 3, 4, 5);
|
||||
final List<Integer> targetList = new ArrayList<>(sourceSet);
|
||||
}
|
||||
|
||||
public final void givenUsingCoreJava_whenListConvertedToSet_thenCorrect() {
|
||||
final List<Integer> sourceList = Lists.newArrayList(0, 1, 2, 3, 4, 5);
|
||||
final Set<Integer> targetSet = new HashSet<>(sourceList);
|
||||
}
|
||||
|
||||
public final void givenUsingGuava_whenSetConvertedToList_thenCorrect() {
|
||||
final Set<Integer> sourceSet = Sets.newHashSet(0, 1, 2, 3, 4, 5);
|
||||
final List<Integer> targetList = Lists.newArrayList(sourceSet);
|
||||
}
|
||||
|
||||
public final void givenUsingGuava_whenListConvertedToSet_thenCorrect() {
|
||||
final List<Integer> sourceList = Lists.newArrayList(0, 1, 2, 3, 4, 5);
|
||||
final Set<Integer> targetSet = Sets.newHashSet(sourceList);
|
||||
}
|
||||
|
||||
public final void givenUsingCommonsCollections_whenListConvertedToSet_thenCorrect() {
|
||||
final List<Integer> sourceList = Lists.newArrayList(0, 1, 2, 3, 4, 5);
|
||||
|
||||
final Set<Integer> targetSet = new HashSet<>(6);
|
||||
CollectionUtils.addAll(targetSet, sourceList);
|
||||
}
|
||||
|
||||
public final void givenUsingCommonsCollections_whenSetConvertedToList_thenCorrect() {
|
||||
final Set<Integer> sourceSet = Sets.newHashSet(0, 1, 2, 3, 4, 5);
|
||||
|
||||
final List<Integer> targetList = new ArrayList<>(6);
|
||||
CollectionUtils.addAll(targetList, sourceSet);
|
||||
}
|
||||
|
||||
// Map (values) -> Array, List, Set
|
||||
|
||||
@Test
|
||||
public final void givenUsingCoreJava_whenMapValuesConvertedToArray_thenCorrect() {
|
||||
final Map<Integer, String> sourceMap = createMap();
|
||||
|
||||
final Collection<String> values = sourceMap.values();
|
||||
final String[] targetArray = values.toArray(new String[values.size()]);
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCoreJava_whenMapValuesConvertedToList_thenCorrect() {
|
||||
final Map<Integer, String> sourceMap = createMap();
|
||||
|
||||
final List<String> targetList = new ArrayList<>(sourceMap.values());
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingGuava_whenMapValuesConvertedToList_thenCorrect() {
|
||||
final Map<Integer, String> sourceMap = createMap();
|
||||
|
||||
final List<String> targetList = Lists.newArrayList(sourceMap.values());
|
||||
}
|
||||
|
||||
@Test
|
||||
public final void givenUsingCoreJava_whenMapValuesConvertedToSet_thenCorrect() {
|
||||
final Map<Integer, String> sourceMap = createMap();
|
||||
|
||||
final Set<String> targetSet = new HashSet<>(sourceMap.values());
|
||||
}
|
||||
|
||||
// UTIL
|
||||
|
||||
private final Map<Integer, String> createMap() {
|
||||
final Map<Integer, String> sourceMap = new HashMap<>(3);
|
||||
sourceMap.put(0, "zero");
|
||||
sourceMap.put(1, "one");
|
||||
sourceMap.put(2, "two");
|
||||
return sourceMap;
|
||||
}
|
||||
|
||||
}
|
||||
@@ -0,0 +1,31 @@
|
||||
package org.baeldung.java.lists;
|
||||
|
||||
import java.util.Arrays;
|
||||
import java.util.List;
|
||||
import java.util.stream.Collectors;
|
||||
|
||||
import org.apache.commons.lang3.StringUtils;
|
||||
import org.junit.Test;
|
||||
|
||||
public class ListToSTring {
|
||||
|
||||
@Test
|
||||
public void whenListToString_thenPrintDefault() {
|
||||
List<Integer> intLIst = Arrays.asList(1, 2, 3);
|
||||
System.out.println(intLIst);
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenCollectorsJoining_thenPrintCustom() {
|
||||
List<Integer> intList = Arrays.asList(1, 2, 3);
|
||||
System.out.println(intList.stream()
|
||||
.map(n -> String.valueOf(n))
|
||||
.collect(Collectors.joining("-", "{", "}")));
|
||||
}
|
||||
|
||||
@Test
|
||||
public void whenStringUtilsJoin_thenPrintCustom() {
|
||||
List<Integer> intList = Arrays.asList(1, 2, 3);
|
||||
System.out.println(StringUtils.join(intList, "|"));
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user