Java Object hashCode() Method

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Description

The Java Object hashCode() method returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.

Declaration

Following is the declaration for java.lang.Object.hashCode() method

public int hashCode()

Parameters

NA

Return Value

This method returns a hash code value for this object.

Exception

NA

Getting HashCode of an GregorianCalendar Example

The following example shows the usage of java.lang.Object.hashCode() method. In this program, we've created a new instance of GregorianCalendar Class. Now using hashCode() method, the hash code of the calendar instance is printed.

package com.tutorialspoint;

import java.util.GregorianCalendar;

public class ObjectDemo {

   public static void main(String[] args) {

      // create a new GregorianCalendar object
      GregorianCalendar cal = new GregorianCalendar();

      // print current time
      System.out.println("" + cal.getTime());

      // print a hashcode for cal
      System.out.println("" + cal.hashCode());
   }
}

Output

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

Fri May 31 16:14:27 IST 2024
943043264

Getting HashCode of an Integer Example

The following example shows the usage of java.lang.Object.hashCode() method. In this program, we've created a new instance of Integer Class. Now using hashCode() method, the hash code of the integer instance is printed.

package com.tutorialspoint;

public class ObjectDemo {

   public static void main(String[] args) {
      // create a new Integer
      Integer i = Integer.valueOf(5);

      // print i
      System.out.println("" + i);

      // print hashcode for i
      System.out.println("" + i.hashCode());
   }
}

Output

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

5
5

Getting HashCode of an ArrayList Example

The following example shows the usage of java.lang.Object.hashCode() method. In this program, we've created a new instance of ArrayList Class. Now using hashCode() method, the hash code of the arrayList instance is printed.

package com.tutorialspoint;

import java.util.ArrayList;

public class ObjectDemo {

   public static void main(String[] args) {
      // create a new ArrayList
      ArrayList<String> i = new ArrayList<>();

      // print i
      System.out.println("" + i);

      // print hashcode for i
      System.out.println("" + i.hashCode());
   }
}

Output

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

[]
1