Languages
[Edit]
EN

Java - get keys and values from HashMap

2 points
Created by:
Root-ssh
7645

Short solution - get all keys and values

Map<String, Integer> map = new HashMap<>();

for (Map.Entry<String, Integer> entry : map.entrySet()) {

    String key = entry.getKey();
    Integer value = entry.getValue();

    System.out.println("Key: " + key + ", Value : " + value);
}

Short solution - get only keys

Map<String, Integer> map = new HashMap<>();
Set<String> keys = map.keySet();

for (String key : keys) {
    System.out.println("Key: " + key);
}

Short solution - get only values

Map<String, Integer> map = new HashMap<>();
Collection<Integer> values = map.values();

for (Integer value : values) {
    System.out.println("Value: " + value);
}

Short solution - get all keys and values - Java 8

Map<String, Integer> map = new HashMap<>();

map.forEach((key, value) -> {
    // use key and value variables
    System.out.println("Key: " + key + ", Value : " + value);
});

1. Get all keys and values

import java.util.HashMap;
import java.util.Map;

public class Example1 {

    public static void main(String[] args) {

        Map<String, Integer> map = new HashMap<>();
        map.put("A", 10);
        map.put("B", 20);
        map.put("C", 30);

        for (Map.Entry<String, Integer> entry : map.entrySet()) {

            String key = entry.getKey();
            Integer value = entry.getValue();

            System.out.println("Key: " + key + ", Value : " + value);
        }
    }
}

Output:

Key: A, Value : 10
Key: B, Value : 20
Key: C, Value : 30

2. Get only keys

import java.util.HashMap;
import java.util.Map;
import java.util.Set;

public class Example2 {

    public static void main(String[] args) {

        Map<String, Integer> map = new HashMap<>();
        map.put("A", 10);
        map.put("B", 20);
        map.put("C", 30);

        Set<String> keys = map.keySet();

        for (String key : keys) {
            System.out.println("Key: " + key);
        }
    }
}

Output:

Key: A
Key: B
Key: C

3. Get only values

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

public class Example3 {

    public static void main(String[] args) {

        Map<String, Integer> map = new HashMap<>();
        map.put("A", 10);
        map.put("B", 20);
        map.put("C", 30);

        Collection<Integer> values = map.values();

        for (Integer value : values) {
            System.out.println("Value: " + value);
        }
    }
}

Output:

Value: 10
Value: 20
Value: 30

4. Get all keys and values - Java 8

import java.util.HashMap;
import java.util.Map;

public class Example4 {

    public static void main(String[] args) {

        Map<String, Integer> map = new HashMap<>();
        map.put("A", 10);
        map.put("B", 20);
        map.put("C", 30);

        map.forEach((key, value) -> {
            // use key and value variables
            System.out.println("Key: " + key + ", Value : " + value);
        });
    }
}

Output:

Key: A, Value : 10
Key: B, Value : 20
Key: C, Value : 30

 

Native Advertising
50 000 ad impressions - 449$
🚀
Get your tech brand or product in front of software developers.
For more information contact us:
Red dot
Dirask - friendly IT community for everyone.

❤️💻 🙂

Join