EN
Java - iterate over HashMap
13 points
Short solution - using forEach from Java 8
xxxxxxxxxx1
Map<String, Integer> map = new HashMap<>();2
map.forEach((key, value) -> {3
// use key and value variables4
System.out.println("Key: " + key + ", Value : " + value);5
});Short solution - using for loop and entrySet()
xxxxxxxxxx1
Map<String, Integer> map = new HashMap<>();2
for (Map.Entry<String, Integer> entry : map.entrySet()) {3
System.out.println("Key: " + entry.getKey() + ", Value : " + entry.getValue());4
}Short solution - using Iterator
xxxxxxxxxx1
Map<String, Integer> map = new HashMap<>();2
Iterator iter = map.entrySet().iterator();3
while (iter.hasNext()) {4
Map.Entry<String, Integer> entry = (Map.Entry<String, Integer>) iter.next();5
System.out.println("Key: " + entry.getKey() + ", Value : " + entry.getValue());6
}Short solution - iterate over keys
xxxxxxxxxx1
Map<String, Integer> map = new HashMap<>();2
map.keySet().forEach(key -> {3
// use key variable4
System.out.println("Key: " + key);5
});Short solution - iterate over values
xxxxxxxxxx1
Map<String, Integer> map = new HashMap<>();2
map.values().forEach(value -> {3
// use key variable4
System.out.println("Value: " + value);5
});xxxxxxxxxx1
import java.util.HashMap;2
import java.util.Map;3
4
public class Example1 {5
6
public static void main(String[] args) {7
8
Map<String, Integer> map = new HashMap<>();9
map.put("A", 10);10
map.put("B", 20);11
map.put("C", 30);12
13
map.forEach((key, value) -> {14
// use key and value variables15
System.out.println("Key: " + key + ", Value : " + value);16
});17
}18
}Output:
xxxxxxxxxx1
Key: A, Value : 102
Key: B, Value : 203
Key: C, Value : 30xxxxxxxxxx1
import java.util.HashMap;2
import java.util.Map;3
4
public class Example2 {5
6
public static void main(String[] args) {7
8
Map<String, Integer> map = new HashMap<>();9
map.put("A", 10);10
map.put("B", 20);11
map.put("C", 30);12
13
for (Map.Entry<String, Integer> entry : map.entrySet()) {14
15
String key = entry.getKey();16
Integer value = entry.getValue();17
18
System.out.println("Key: " + key + ", Value : " + value);19
}20
}21
}Output:
xxxxxxxxxx1
Key: A, Value : 102
Key: B, Value : 203
Key: C, Value : 30xxxxxxxxxx1
import java.util.HashMap;2
import java.util.Iterator;3
import java.util.Map;4
5
public class Example3 {6
7
public static void main(String[] args) {8
9
Map<String, Integer> map = new HashMap<>();10
map.put("A", 10);11
map.put("B", 20);12
map.put("C", 30);13
14
Iterator iter = map.entrySet().iterator();15
while (iter.hasNext()) {16
Map.Entry<String, Integer> entry = 17
(Map.Entry<String, Integer>) iter.next();18
19
String key = entry.getKey();20
Integer value = entry.getValue();21
22
System.out.println("Key: " + key + ", Value : " + value);23
}24
}25
}Output:
xxxxxxxxxx1
Key: A, Value : 102
Key: B, Value : 203
Key: C, Value : 30xxxxxxxxxx1
import java.util.HashMap;2
import java.util.Map;3
4
public class Example4 {5
6
public static void main(String[] args) {7
8
Map<String, Integer> map = new HashMap<>();9
map.put("A", 10);10
map.put("B", 20);11
map.put("C", 30);12
13
map.keySet().forEach(key -> {14
// use key variable15
System.out.println("Key: " + key);16
});17
}18
}Output:
xxxxxxxxxx1
Key: A2
Key: B3
Key: Cxxxxxxxxxx1
import java.util.HashMap;2
import java.util.Map;3
4
public class Example5 {5
6
public static void main(String[] args) {7
8
Map<String, Integer> map = new HashMap<>();9
map.put("A", 10);10
map.put("B", 20);11
map.put("C", 30);12
13
map.values().forEach(value -> {14
// use key variable15
System.out.println("Value: " + value);16
});17
}18
}Output:
xxxxxxxxxx1
Value: 102
Value: 203
Value: 30