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Java Hashtable keySet() Method with Example

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

Hashtable Class keySet() method

• keySet() method is available in java.util package.
• keySet() method is used to return a set of keys to be viewed in a set in this Hashtable.
• keySet() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• keySet() method does not throw an exception at the time of returning keys in a set view.

Syntax:

    public Set keySet();

Parameter(s):

• It does not accept any parameter.

Return value:

The return type of the method is Set, it returns keys in a set view of this Hashtable.

Example:

// Java program to demonstrate the example 
// of Set keySet() method of Hashtable 

import java.util.*;

public class KeySetOfHashtable {
    public static void main(String[] args) {

        //Instantiate a hashtable object  
        Hashtable ht = new Hashtable();

        // By using put() method is to
        // add the linked values in an
        // Hashtable ht
        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 keySet() method is to
        // return th set of keys exists in
        // Hashtable to be viewed in a set
        Set s = ht.keySet();

        // Display Hashtable in a set view
        System.out.println("ht.keySet(): " + s);

    }
}

Output

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