Hashtable
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(); hashtable.put("key_1","value_1"); hashtable.put("key_2","value_2"); hashtable.put("key_3","value_3"); // 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); } }
Output:
key_2 exists in Hashtable ? : true
This was an example of how to check a key existence in a Hashtable in Java.