Java Hashtable size() Method

---

---

Description

The Java Hashtable size() method is used to get the number of keys in this hashtable.

Declaration

Following is the declaration for java.util.Hashtable.size() method.

public int size()

Parameters

NA

Return Value

The method call returns the number of keys in this hashtable.

Exception

NA

Getting Size of a HashTable of Integer, Integer Pair Example

The following example shows the usage of Java Hashtable size() method to get a size of a Hashtable. We've created a Hashtable object of Integer,Integer pairs. Then few entries are added, table is printed. Using size() method, size of table is retrieved and printed.

package com.tutorialspoint;

import java.util.Hashtable;

public class HashtableDemo {
   public static void main(String args[]) {
      
      // create hash table
      Hashtable<Integer,Integer> hashtable = new Hashtable<>();

      // populate hash table
      hashtable.put(1, 1);
      hashtable.put(2, 2);
      hashtable.put(3, 3); 

      System.out.println("Initial table elements: " + hashtable);

      System.out.println("Size of the table: " + hashtable.size());
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Initial table elements: {3=3, 2=2, 1=1}
Size of the table: 3

Getting Size of a HashTable of Integer, String Pair Example

The following example shows the usage of Java Hashtable size() method to get a size of a Hashtable. We've created a Hashtable object of Integer,String pairs. Then few entries are added, table is printed. Using size() method, size of table is retrieved and printed.

package com.tutorialspoint;

import java.util.Hashtable;

public class HashtableDemo {
   public static void main(String args[]) {
      
      // create hash table
      Hashtable<Integer,String> hashtable = new Hashtable<>();

      // populate hash table
      hashtable.put(1, "tutorials");
      hashtable.put(2, "point");
      hashtable.put(3, "is best"); 

      System.out.println("Initial table elements: " + hashtable);

      System.out.println("Size of the table: " + hashtable.size());
   }    
}

Output

Let us compile and run the above program, this will produce the following result.

Initial table elements: {3=is best, 2=point, 1=tutorials}
Size of the table: 3

Getting Size of a HashTable of Integer, Object Pair Example

The following example shows the usage of Java Hashtable size() method to get a size of a Hashtable. We've created a Hashtable object of Integer,Student pairs. Then few entries are added, table is printed. Using size() method, size of table is retrieved and printed.

package com.tutorialspoint;

import java.util.Hashtable;

public class HashtableDemo {
   public static void main(String args[]) {
      
      // create hash table
      Hashtable<Integer,Student> hashtable = new Hashtable<>();

      // populate hash table
      hashtable.put(1, new Student(1, "Julie"));
      hashtable.put(2, new Student(2, "Robert"));
      hashtable.put(3, new Student(3, "Adam"));

      System.out.println("Initial table elements: " + hashtable);

      System.out.println("Size of the table: " + hashtable.size());
   }    
}
class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}

Output

Let us compile and run the above program, this will produce the following result.

Initial table elements: {3=[ 3, Adam ], 2=[ 2, Robert ], 1=[ 1, Julie ]}
Size of the table: 3