Hashtable clear() Method in Java

The java.util.Hashtable.clear() method in Java is used to clear and remove all of the keys from a specified Hashtable. 

Syntax:

Hash_table.clear()

Parameters: The method does not accept any parameters. 

Return Value: The method does not return any value. Below programs are used to illustrate the working of java.util.Hashtable.clear() Method: 

Program 1:

Java

// Java code to illustrate the clear() method
import java.util.*;

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

        // Creating an empty Hashtable
        Hashtable<Integer, String> hash_table = new Hashtable<Integer, String>();

        // Inserting Values into table
        hash_table.put(10, "Geeks");
        hash_table.put(15, "4");
        hash_table.put(20, "Geeks");
        hash_table.put(25, "Welcomes");
        hash_table.put(30, "You");

        // Displaying the Hashtable
        System.out.println("The Hashtable is: " + hash_table);

        // Clearing the hash table using clear()
        hash_table.clear();

        // Displaying the final Hashtable
        System.out.println("Finally the table looks like this: " + hash_table);
    }
}

Output:

The Hashtable is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
Finally the table looks like this: {}

Program 2:

Java

// Java code to illustrate the clear() method
import java.util.*;

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

        // Creating an empty Hashtable
        Hashtable<String, Integer> hash_table = new Hashtable<String, Integer>();

        // Inserting Values into table
        hash_table.put("Geeks", 10);
        hash_table.put("4", 15);
        hash_table.put("Geeks", 20);
        hash_table.put("Welcomes", 25);
        hash_table.put("You", 30);

        // Displaying the Hashtable
        System.out.println("The Hashtable is: " + hash_table);

        // Clearing the hash table using clear()
        hash_table.clear();

        // Displaying the final Hashtable
        System.out.println("Finally the table looks like this: " + hash_table);
    }
}

Output:

The Hashtable is: {You=30, Welcomes=25, 4=15, Geeks=20}
Finally the table looks like this: {}

Note: The same operation can be performed with any type of variation and combination of different data types.