Remove mapping from HashMap example

This is an example of how to remove mapping from a HashMap, that is removing a key value pair from a HashMap. Removing mapping from a HashMap implies that you should:

  • Create a new HashMap.
  • Populate the hashMap with elements, with the put(K key, V value) API method of HashMap.
  • Invoke the remove(Object key) API method of HashMap, to remove a key value pair from the hashMap. It returns either the value mapped with the key previously or null if no value was mapped.

Let’s take a look at the code snippet that follows:

package com.javacodegeeks.snippets.core;

import java.util.HashMap;
public class RemoveMappingHashMap {
  public static void main(String[] args) {
    // Create a HashMap and populate it with elements
    HashMap hashMap = new HashMap();
    System.out.println("HashMap contains : " + hashMap);


Object remove(Object key) operantion removes a key value pair from HashMap. 

It returns either the value mapped with the key previously or null if no value was mapped.     
    Object value = hashMap.remove("key_2");

    System.out.println("After removing value : " + value + " HashMap contains : " + hashMap);


HashMap contains : {key_3=value_3, key_2=value_2, key_1=value_1}
After removing value : value_2 HashMap contains : {key_3=value_3, key_1=value_1}

This was an example of how to remove mapping from a HashMap in Java.

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Byron Kiourtzoglou

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.
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