Check key existence in Hashtable example

With this example we are going to demonstrate how to check a key existence in a Hashtable. In short, to check if a key exists in a Hashtable you should:

  • Create a new Hashtable.
  • Populate the hashtable with elements, using put(K key, V value) API method of Hashtable.
  • Invoke the containsKey(Object key) API method of Hashtable, with a key as parameter. The method returns true if and only if the specified object is a key in this hashtable, as determined by the equals method and false otherwise.

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

package com.javacodegeeks.snippets.core;
import java.util.Hashtable;
public class CheckKeyHashtable {
  public static void main(String[] args) {
    // Create a Hashtable and populate it with elements
    Hashtable hashtable = new Hashtable();
    // boolean containsKey(Object key) returns true if the Hashtable contains the key, otherwise false.
    boolean exists = hashtable.containsKey("key_2");
    System.out.println("key_2 exists in Hashtable ? : " + exists);



key_2 exists in Hashtable ? : true

This was an example of how to check a key existence in a Hashtable in Java.

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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