Java TreeMap.descendingMap() example

In this java tutorial, You will learn how to use descendingKeySet() method of TreeMap class.The descendingMap() method is used to return a reverse order view of the mappings contained in this map. The descending map is backed by this map, so changes to the map are reflected in the descending map, and vice-versa.

Returns a reverse order view of the mappings contained in this map.

syntax

public NavigableMap<K,V> descendingMap()

Returns

a reverse order view of this map.

Java TreeMap descendingMap() example

  • Create TreeMap instance new TreeMap < Integer, String > ();
  • Add few elements in TreeMap e.g. students.put(1, "Pooja");
  • Print the TreeMap values.
  • students.descendingMap(); returns a reverse order view of the mappings contained in this map
  • Print descending map values.
package com.technicalkeeda;

import java.util.NavigableMap;
import java.util.TreeMap;

public class App {
    public static void main(String args[]) {

        TreeMap < Integer, String > students = new TreeMap < Integer, String > ();

        students.put(1, "Pooja");
        students.put(2, "Ajit");
        students.put(3, "Yashwant");
        students.put(4, "Aditi");

        System.out.println("TreeMap values :- " + students);

        NavigableMap reverseStudent = students.descendingMap();

        System.out.println("Values in reverse order:- " + reverseStudent);

    }
}

output

TreeMap values :- {1=Pooja, 2=Ajit, 3=Yashwant, 4=Aditi}
Values in reverse order:- {4=Aditi, 3=Yashwant, 2=Ajit, 1=Pooja}