Java Hashtable hashCode() Method

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Description

The Java Hashtable hashCode() method is used to get the hash code value for this Hashtable as per the definition in the Hashtable interface.

Declaration

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

public int hashCode()

Parameters

NA

Return Value

The method call returns a hash code value for this object.

Exception

NA

Getting HashCode From a HashTable of Integer, Integer Pair Example

The following example shows the usage of Java Hashtable hashCode() method to print the hashcode of the hashtable. We've created a Hashtable object of Integer,Integer pairs. Then few entries are added, table is printed and using hashCpde() we're printing the hashcode of the hashtable.

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("Hashcode: " + hashtable.hashCode());
   }    
}

Output

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

Initial table elements: {3=3, 2=2, 1=1}
Hashcode: 0

Getting HashCode From a HashTable of Integer, String Pair Example

The following example shows the usage of Java Hashtable hashCode() method to print the hashcode of the hashtable. We've created a Hashtable object of Integer,String pairs. Then few entries are added, table is printed and using hashCpde() we're printing the hashcode of the hashtable.

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("Hashcode: " + hashtable.hashCode());
   }    
}

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}
Hashcode: -467977857

Getting HashCode From a HashTable of Integer, Object Pair Example

The following example shows the usage of Java Hashtable hashCode() method to print the hashcode of the hashtable. We've created a Hashtable object of Integer,Student pairs. Then few entries are added, table is printed and using hashCpde() we're printing the hashcode of the hashtable.

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("Hashcode: " + hashtable.hashCode());
   }    
}
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 + " ]";
   }
   @Override
   public boolean equals(Object obj) {
      if(obj == null) return false;
      Student s = (Student)obj;
      return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.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 ]}
Hashcode: -468474580