Remove the first entry of the TreeMap in Java

To remove the first entry of the TreeMap, use the pollFirstEntry() method.

Let us first create a TreeMap and add elements −

TreeMap<Integer,String> m = new TreeMap<Integer,String>(); m.put(1,"India"); m.put(2,"US"); m.put(3,"Australia"); m.put(4,"Netherlands"); m.put(5,"Canada");

Remove the first entry now −

m.pollFirstEntry()

The following is an example to remove the first entry of the TreeMap.

Example

 Live Demo

import java.util.*; public class Demo { public static void main(String args[]) { TreeMap<Integer,String> m = new TreeMap<Integer,String>(); m.put(1,"India"); m.put(2,"US"); m.put(3,"Australia"); m.put(4,"Netherlands"); m.put(5,"Canada"); System.out.println("TreeMap Elements = "+m); System.out.println("Removing First Entry : "+m.pollFirstEntry()); System.out.println("Updated TreeMap Elements = "+m); } }

Output

TreeMap Elements = {1=India, 2=US, 3=Australia, 4=Netherlands, 5=Canada} Removing First Entry = 1=India Updated TreeMap Elements = {2=US, 3=Australia, 4=Netherlands, 5=Canada}