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Hashtable size() Method in Java

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  • Difficulty Level : Hard
  • Last Updated : 28 Jun, 2018

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 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 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.


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