java.util.TreeMap.pollFirstEntry() Method

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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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