Hashtable toString() Method in Java

The toString() method in the Hashtable class in Java returns a string representation of the key-value mappings contained in the hashtable. The string is in the form of a comma-separated list of key-value pairs enclosed in curly braces.

The toString() method is inherited from the java.util.Hashtable class’s parent class, java.util.Dictionary.

Here’s an example of using the toString() method:

Java

import java.util.Hashtable;

public class HashtableExample {
    public static void main(String[] args)
    {
        Hashtable<String, Integer> ht = new Hashtable<>();
        ht.put("Alice", 25);
        ht.put("Bob", 30);
        ht.put("Charlie", 35);

        System.out.println(ht.toString());
    }
}

Output

{Bob=30, Charlie=35, Alice=25}

The java.util.Hashtable.toString() is an inbuilt method of Hashtable that is used to get a string representation of the objects of Hashtable in the form of a set of entries separated by “, “. So basically the toString() method is used to convert all the elements of Hashtable into String.

Syntax:

Hash_Table.toString()

Parameter: The method does not take any parameters.
Return value: The method returns the set consisting of the string representation of the elements of the hash table.

Below programs illustrate the working of java.util.Hashtable.toString() method: 

Program 1:

Java

// Java code to illustrate the toString() 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 elements into the 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("Initial table is: "
                           + hash_table);

        // Displaying the string representation
        System.out.println("The set is: "
                           + hash_table.toString());
    }
}

Output

Initial table is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
The set is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}

Program 2:

Java

// Java code to illustrate the toString() 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 elements into the 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("Initial Table is: "
                           + hash_table);

        // Displaying the string representation
        System.out.println("The set is: "
                           + hash_table.toString());
    }
}

Output

Initial Table is: {You=30, Welcomes=25, 4=15, Geeks=20}
The set is: {You=30, Welcomes=25, 4=15, Geeks=20}