Set hashCode() Method in Java (original) (raw)

Last Updated : 06 Feb, 2025

In Java, the hashCode() method is defined in the Object class and is used to generate a hash code for objects. It plays a very important role in hash-based collections like HashMap, HashSet, and HashTable.

Example 1: This example demonstrates **how hashCode() is used to get the hash code of the **HashSet_**.**_

Java `

// Java Program to demonstrate the working of // hashCode() method in Set import java.util.*;

public class Geeks { public static void main(String[] args) { // creating an Set Set s = new HashSet();

    // using add() to insert elements
    s.add(1); 
    s.add(2); 
    s.add(3); 
    s.add(4); 

    System.out.println("Set: " + s); 

    // Get the hashCode value 
    // using hashCode() value 
    System.out.println("HashCode value: " 
    + s.hashCode()); 
} 

}

`

Output

Set: [1, 2, 3, 4] HashCode value: 10

Syntax of hashCode() Method

public int hashCode()

• **Parameter: This method does not take any parameter.
• **Return Type: This method return an int value.

**Example 2: This example demonstrates that **without overriding hashCode(), different objects with similar data have different hash codes.

Java `

// Java program to demonstrates hashcode() // value for different objects class Geeks { int id; String name;

public Geeks(int id, String name)
{
    this.id = id;
    this.name = name;
}

public static void main(String[] args)
{
    Geeks obj1 = new Geeks(1, "John");
    Geeks obj2 = new Geeks(1, "John");

    System.out.println("hashCode of obj1: "
                       + obj1.hashCode());
    System.out.println("hashCode of obj2: "
                       + obj2.hashCode());
}

}

`

Output

hashCode of obj1: 1510467688 hashCode of obj2: 868693306