java.util.HashMap.put() Method

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Description

The put(K key, V value) method is used to associate the specified value with the specified key in this map.

Declaration

Following is the declaration for java.util.HashMap.put() method.

public V put(K key, V value)

Parameters

• key − This is the key with which the specified value is to be associated.

• value − This is the value to be associated with the specified key.

Return Value

The method call returns the previous value associated with key, or null if there was no mapping for key.

Exception

NA

Example

The following example shows the usage of java.util.HashMap.put()

package com.tutorialspoint;

import java.util.*;

public class HashMapDemo {
   public static void main(String args[]) {
      
      // create hash map
      HashMap newmap = new HashMap();

      // populate hash map
      newmap.put(1, "tutorials");
      newmap.put(2, "point");
      newmap.put(3, "is best");

      System.out.println("Map value before change: "+ newmap);

      // put new values at key 3
      String prevvalue = (String)newmap.put(3,"is great");

      // check returned previous value
      System.out.println("Returned previous value: "+ prevvalue);

      System.out.println("Map value after change: "+ newmap);
   }    
}

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

Map value before change: {1=tutorials, 2=point, 3=is best}
Returned previous value: is best
Map value after change: {1=tutorials, 2=point, 3=is great}