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MapIteration changes (#2072)

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PRITAM BANERJEE
2017-06-26 03:36:16 -07:00
committed by Grzegorz Piwowarek
parent 2bb31e54ed
commit b97651ae5a
2 changed files with 41 additions and 97 deletions
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69
core-java/src/main/java/com/baeldung/map/iteration/MapIteration.java
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@@ -1,58 +1,71 @@
package com.baeldung.map.iteration;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
public class MapIteration {
public List<String> iterateUsingEntrySet(Map<String, Integer> map) {
List<String> mapKeyValueList = new ArrayList<>();
public static void main(String[] args) {
MapIteration mapIteration = new MapIteration();
Map<String, Integer> 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<String, Integer> map) {
for (Map.Entry<String, Integer> entry : map.entrySet()) {
mapKeyValueList.add(entry.getKey() + ":" + entry.getValue());
System.out.println(entry.getKey() + ":" + entry.getValue());
}
return mapKeyValueList;
}
public List<String> iterateUsingLambda(Map<String, Integer> map) {
List<String> mapKeyValueList = new ArrayList<>();
map.forEach((k, v) -> mapKeyValueList.add(k + ":" + v));
return mapKeyValueList;
public void iterateUsingLambda(Map<String, Integer> map) {
map.forEach((k, v) -> System.out.println((k + ":" + v)));
}
public List<String> iterateUsingIteratorAndEntry(Map<String, Integer> map) {
ArrayList<String> mapKeyValueList = new ArrayList<>();
public void iterateUsingIteratorAndEntry(Map<String, Integer> map) {
Iterator<Map.Entry<String, Integer>> iterator = map.entrySet().iterator();
while (iterator.hasNext()) {
Map.Entry<String, Integer> pair = iterator.next();
mapKeyValueList.add(pair.getKey() + ":" + pair.getValue());
System.out.println(pair.getKey() + ":" + pair.getValue());
}
return mapKeyValueList;
}
public List<String> iterateUsingKeySetAndForeach(Map<String, Integer> map) {
List<String> mapKeyValueList = new ArrayList<>();
public void iterateUsingKeySetAndForeach(Map<String, Integer> map) {
for (String key : map.keySet()) {
mapKeyValueList.add(key + ":" + map.get(key));
System.out.println(key + ":" + map.get(key));
}
return mapKeyValueList;
}
public List<String> iterateUsingStreamAPI(Map<String, Integer> map) {
ArrayList<String> mapKeyValueList = new ArrayList<>();
map.entrySet().stream().forEach(e -> mapKeyValueList.add(e.getKey() + ":" + e.getValue()));
return mapKeyValueList;
public void iterateUsingStreamAPI(Map<String, Integer> map) {
map.entrySet().stream().forEach(e -> System.out.println(e.getKey() + ":" + e.getValue()));
}
public ArrayList<String> iterateKeys(Map<String, Integer> map) {
ArrayList<String> mapKeyList = new ArrayList<>();
public void iterateKeys(Map<String, Integer> map) {
for (String key : map.keySet()) {
mapKeyList.add(key);
System.out.println(key);
}
return mapKeyList;
}
}