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Java Hashtable containsKey() Method with Example

Hashtable Class containsKey() method: Here, we are going to learn about the containsKey() method of Hashtable Class with its syntax and example.
Submitted by Preeti Jain, on February 17, 2020

Hashtable Class containsKey() method

• containsKey() method is available in java.util package.
• containsKey() method is used to check whether the given object is a key element (key_ele) or not.
• containsKey() method is a non-static method, it is accessible with the class object and if we try to access the method with the class name then we will get an error.
• containsKey() method may throw an exception at the time of checking the key.
  NullPointerException: This exception may throw when the given parameter is null exists.

Syntax:

    public boolean containsKey(Object key_ele);

Parameter(s):

• Object key_ele – represents the key element (key_ele) to be tested for existence.

Return value:

The return type of the method is boolean, it returns true when the given object is a key element (key_ele) otherwise it returns false.

Example:

// Java program is to demonstrate the example of
// containsKey() method of Hashtable

import java.util.*;

public class ContainsKeyOfHashtable {
    public static void main(String[] args) {
        //Instantiate two hashtable object  
        Hashtable ht = new Hashtable();

        // By using put() method is to
        // add the linked values in an Hashtable
        ht.put(10, "C");
        ht.put(20, "C++");
        ht.put(30, "JAVA");
        ht.put(40, "PHP");
        ht.put(50, "SFDC");

        // Display Hashtable
        System.out.println("Hashtable: " + ht);

        // By using containsKey() method is to
        // check whether the given element
        // is a key element or not in this Hashtable
        boolean status = ht.containsKey(30);

        // Display Status
        System.out.println("ht.containsKey(30): " + status);
    }
}

Output

Hashtable: {10=C, 20=C++, 30=JAVA, 40=PHP, 50=SFDC}
ht.containsKey(30): true