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Java Hashtable rehash() Method with Example

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

Hashtable Class rehash() method

• rehash() method is available in java.util package.
• rehash() method is used to extend the capacity and it is invoked implicitly if the number of keys limit exceeds hashtable capacity.
• rehash() 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.
• rehash() method does not throw an exception at the time of extending capacity.

Syntax:

    public void rehash();

Parameter(s):

• It does not accept any parameter.

Return value:

The return type of the method is void, it returns nothing.

Example:

// Java program to demonstrate the example 
// of void rehash() method of Hashtable 

import java.util.*;

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

        // 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 rehash() method is to increase
        // the capacity and re-organizes internally
        // this Hashtable

        ht.rehash();
        System.out.println("ht.size(): " + ht.size());
    }
}

Output

Hashtable: {10=C, 20=C++, 30=JAVA, 40=PHP, 50=SFDC}
ht.size(): 5