Sort Maps by Value in Java 8 [Snippet]

The following demonstrates how to sort a given map based on the value using Java 8. One important thing to keep in mind is that you cannot sort a map in the Hashmap object.

 map.entrySet().stream().sorted((o1, o2) -> o1.getValue().compareTo(o2.getValue())).map(e -> e.getKey()).collect(Collectors.toList()).forEach(k -> sortedMap.put(k, map.get(k))); 

The full implementation of the code would look something like this: 

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.stream.Collectors;

public class C {
public static void main(String[] args) {
Map<String, Integer> map = new HashMap<String, Integer>();
Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>();
map.put(“a”, 21);
map.put(“b”, 10);
map.put(“c”, 12);
map.put(“d”, 21);
map.entrySet().stream().sorted((o1, o2) -> o1.getValue().compareTo(o2.getValue())).map(e -> e.getKey()).collect(Collectors.toList()).forEach(k -> sortedMap.put(k, map.get(k)));
System.out.println(sortedMap);
}
}

Hope this is helpful!