JAVA

java map get key from value

import java.util.HashMap;
import java.util.Map;
 
class Main
{
    public static <K, V> K getKey(Map<K, V> map, V value)
    {
        return map.entrySet().stream()
                .filter(entry -> value.equals(entry.getValue()))
                .findFirst().map(Map.Entry::getKey)
                .orElse(null);
    }
 
    public static void main(String[] args)
    {
        Map<String, Integer> hashMap = new HashMap();
        hashMap.put("A", 1);
        hashMap.put("B", 2);
        hashMap.put("C", 3);
 
        System.out.println(getKey(hashMap, 2));        // prints `B`
    }
}

java map get value

// Java code to illustrate the get() method
import java.util.*;

public class Map_Demo {
	public static void main(String[] args)
	{
		// Creating an empty Map
		Map<Integer, String> map = new HashMap<Integer, String>();

		// Mapping string values to int keys
		map.put(10, "Geeks");
		map.put(15, "4");
		map.put(20, "Geeks");
		map.put(25, "Welcomes");
		map.put(30, "You");

		// Displaying the Map
		System.out.println("Initial Mappings are: " + map);

		// Getting the value of 25
		System.out.println("The Value is: " + map.get(25));

		// Getting the value of 10
		System.out.println("The Value is: " + map.get(10));
	}
}