java.util.TreeMap.firstEntry() Method


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Description

The firstEntry() method is used to return 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.firstEntry() method.

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

Parameters

NA

Return Value

The method call returns an entry with the least key, or null if this map is empty.

Exception

NA

Example

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

Live Demo
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");

      System.out.println("Checking first entry");
      System.out.println("First entry is: "+ treemap.firstEntry());
   }    
}

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

Checking first entry
First entry is: 1=one

java_util_treemap.htm

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