Check whether a NavigableMap empty or not in Java

The isEmpty() method is used in Java to check whether a NavigableMap is empty or not.

First, create a NavigableMap and add elements to it −

NavigableMap<Integer, String> n = new TreeMap<Integer, String>();
n.put(5, "Tom");
n.put(9, "John");
n.put(14, "Jamie");
n.put(1, "Tim");
n.put(4, "Jackie");
n.put(15, "Kurt");
n.put(19, "Tiger");
n.put(24, "Jacob");

Now, check whether the Map is empty or not −

System.out.println("Map is empty? " + n.isEmpty());

The following is an example to implement isEmpty() method and check whether the Map is empty −

Example

 Live Demo

import java.util.*;
public class Demo {
   public static void main(String[] args) {
      NavigableMap<Integer, String> n = new TreeMap<Integer, String>();
      n.put(5, "Tom");
      n.put(9, "John");
      n.put(14, "Jamie");
      n.put(1, "Tim");
      n.put(4, "Jackie");
      n.put(15, "Kurt");
      n.put(19, "Tiger");
      n.put(24, "Jacob");
      System.out.println("NavigableMap elements = "+n);
      System.out.println("Size = "+n.size());
      System.out.println("Map is empty? " + n.isEmpty());
      // remove all elements
      n.clear();
      System.out.println("\nUpdated NavigableMap elements = "+n);
      System.out.println("Size = "+n.size());
      System.out.println("Map is empty? " + n.isEmpty());
   }
}

Output

NavigableMap elements = {1=Tim, 4=Jackie, 5=Tom, 9=John, 14=Jamie, 15=Kurt, 19=Tiger, 24=Jacob}
Size = 8
Map is empty? false
Updated NavigableMap elements = {}
Size = 0
Map is empty? True