iSharkFly-Docs/java-tutorials
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

MapIteration changes (#2072)

Browse Source
This commit is contained in:
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

69
core-java/src/main/java/com/baeldung/map/iteration/MapIteration.java
View File

@ -1,58 +1,71 @@
package com.baeldung.map.iteration; package com.baeldung.map.iteration;
import java.util.ArrayList; import java.util.HashMap;
import java.util.Iterator; import java.util.Iterator;
import java.util.List;
import java.util.Map; import java.util.Map;
public class MapIteration { public class MapIteration {
public List<String> iterateUsingEntrySet(Map<String, Integer> map) { public static void main(String[] args) {
List<String> mapKeyValueList = new ArrayList<>(); 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()) { 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) { public void iterateUsingLambda(Map<String, Integer> map) {
List<String> mapKeyValueList = new ArrayList<>(); map.forEach((k, v) -> System.out.println((k + ":" + v)));
map.forEach((k, v) -> mapKeyValueList.add(k + ":" + v));
return mapKeyValueList;
} }
public List<String> iterateUsingIteratorAndEntry(Map<String, Integer> map) { public void iterateUsingIteratorAndEntry(Map<String, Integer> map) {
ArrayList<String> mapKeyValueList = new ArrayList<>();
Iterator<Map.Entry<String, Integer>> iterator = map.entrySet().iterator(); Iterator<Map.Entry<String, Integer>> iterator = map.entrySet().iterator();
while (iterator.hasNext()) { while (iterator.hasNext()) {
Map.Entry<String, Integer> pair = iterator.next(); 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) { public void iterateUsingKeySetAndForeach(Map<String, Integer> map) {
List<String> mapKeyValueList = new ArrayList<>();
for (String key : map.keySet()) { 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) { public void iterateUsingStreamAPI(Map<String, Integer> map) {
ArrayList<String> mapKeyValueList = new ArrayList<>(); map.entrySet().stream().forEach(e -> System.out.println(e.getKey() + ":" + e.getValue()));
map.entrySet().stream().forEach(e -> mapKeyValueList.add(e.getKey() + ":" + e.getValue()));
return mapKeyValueList;
} }
public ArrayList<String> iterateKeys(Map<String, Integer> map) { public void iterateKeys(Map<String, Integer> map) {
ArrayList<String> mapKeyList = new ArrayList<>();
for (String key : map.keySet()) { for (String key : map.keySet()) {
mapKeyList.add(key); System.out.println(key);
} }
return mapKeyList;
} }
} }

69
core-java/src/test/java/com/baeldung/map/iteration/MapIterationTest.java
View File

@ -1,69 +0,0 @@
package com.baeldung.map.iteration;
import static org.junit.Assert.assertTrue;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.junit.BeforeClass;
import org.junit.Test;
public class MapIterationTest {
public static Map<String, Integer> testMap = new HashMap<String, Integer>();
public static String testString1 = "One:1";
public static String testString2 = "Two:2";
public static String testString3 = "Three:3";
@BeforeClass
public static void createTestData() {
testMap.put("One", 1);
testMap.put("Three", 3);
testMap.put("Two", 2);
}
@Test
public void givenMap_whenIterateUsingEntrySetReturnsAllEntries_thenCorrect() {
MapIteration mapIteration = new MapIteration();
List<String> list = mapIteration.iterateUsingEntrySet(testMap);
assertTrue((list.contains(testString1)) && (list.contains(testString2)) && (list.contains(testString3)));
}
@Test
public void givenMap_whenIterateUsingLambdaReturnsAllEntries_thenCorrect() {
MapIteration mapIteration = new MapIteration();
List<String> list = mapIteration.iterateUsingLambda(testMap);
assertTrue((list.contains(testString1)) && (list.contains(testString2)) && (list.contains(testString3)));
}
@Test
public void givenMap_whenIterateUsingIteratorAndEntryReturnsAllEntries_thenCorrect() {
MapIteration mapIteration = new MapIteration();
List<String> list = mapIteration.iterateUsingIteratorAndEntry(testMap);
assertTrue((list.contains(testString1)) && (list.contains(testString2)) && (list.contains(testString3)));
}
@Test
public void givenMap_whenIterateUsingKeySetAndForeachReturnsAllEntries_thenCorrect() {
MapIteration mapIteration = new MapIteration();
List<String> list = mapIteration.iterateUsingKeySetAndForeach(testMap);
assertTrue((list.contains(testString1)) && (list.contains(testString2)) && (list.contains(testString3)));
}
@Test
public void givenMap_whenIterateUsingStreamAPIReturnsAllEntries_thenCorrect() {
MapIteration mapIteration = new MapIteration();
List<String> list = mapIteration.iterateUsingStreamAPI(testMap);
assertTrue((list.contains(testString1)) && (list.contains(testString2)) && (list.contains(testString3)));
}
@Test
public void givenMap_whenIterateUsingKeysReturnsAllKeys_thenCorrect() {
MapIteration mapIteration = new MapIteration();
ArrayList<String> list = mapIteration.iterateKeys(testMap);
assertTrue((list.contains("One")) && (list.contains("Two")) && (list.contains("Three")));
}
}