Hashtable size() Method in Java

The java.util.Hashtable.size() method of Hashtable class is used to get the size of the table which refers to the number of the key-value pair or mappings in the Table. 

Syntax:

Hash_Table.size()

Parameters: The method does not take any parameters. 

Return Value: The method returns the size of the table which also means the number of key-value pairs present in the table. Below programs illustrates the working of java.util.Hashtable.size(): 

Program 1:

Java

// Java code to illustrate the size() 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 size of the table
        System.out.println("The size of the table is " +
        hash_table.size());
    }
}

Output:

Initial table is: {10=Geeks, 20=Geeks, 30=You, 15=4, 25=Welcomes}
The size of the table is 5

Program 2:

Java

// Java code to illustrate the size() 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 size of the table
        System.out.println("The size of the table is " +
        hash_table.size());
    }
}

Output:

Initial Table is: {You=30, Welcomes=25, 4=15, Geeks=20}
The size of the table is 4

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