java.util.TreeMap.pollFirstEntry() Method

Description

The pollFirstEntry() method is used to remove and returns a key-value mapping associated with the least key in this map, or null if the map is empty.

Declaration

Following is the declaration for java.util.TreeMap.pollFirstEntry() method.

public Map.Entry<K,V> pollFirstEntry()

Parameters

NA

Return Value

The method call returns the removed first entry of this map, or null if this map is empty.

Exception

NA

Example

The following example shows the usage of java.util.TreeMap.pollFirstEntry()

package com.tutorialspoint;

import java.util.*;

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

      // creating tree map 
      TreeMap<Integer, String> treemap = new TreeMap<Integer, String>();

      // populating tree map
      treemap.put(2, "two");
      treemap.put(1, "one");
      treemap.put(3, "three");
      treemap.put(6, "six");
      treemap.put(5, "five");   

      // polling first entry
      System.out.println("Value before poll: "+ treemap);            
      System.out.println("Value returned: "+ treemap.pollFirstEntry());      
      System.out.println("Value after poll: "+ treemap);
   }     
}

Let us compile and run the above program, this will produce the following result.

Value before poll: {1=one, 2=two, 3=three, 5=five, 6=six}
Value returned: 1=one
Value after poll: {2=two, 3=three, 5=five, 6=six}

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