Sort map by key in java

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

public class SortByKeyExample2 {

public static void main(String[] args) {

Map<Integer, String> map = new HashMap<Integer, String>();
map.put(1, “A”);
map.put(5, “D”);
map.put(3, “C”);
map.put(6, “B”);
map.put(9, “E”);
map.put(2, “F”);

Map<Integer, String> sortedMap = new TreeMap<Integer, String>(new Comparator<Integer>() {

@Override
public int compare(Integer o1, Integer o2) {
return o1.compareTo(o2);
}

});

// For Java 8, using lambda
//Map<Integer, String> sortedMap = new TreeMap<>((Comparator<Integer>) (o1, o2) -> o2.compareTo(o1));

sortedMap.putAll(map);

System.out.println(“Original Map :”+map);
System.out.println(“Sorted Map by key :”+sortedMap);

}

}

Output:

Original Map :{1=A, 2=F, 3=C, 5=D, 6=B, 9=E}
Sorted Map by key :{1=A, 2=F, 3=C, 5=D, 6=B, 9=E}