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Integer hashCode() Method in Java

  • Last Updated : 05 Dec, 2018
Geek Week

The java.lang.Integer.hashCode() method of Integer class in Java is used to return the hash code for a particular Integer .

Syntax:

public int hashCode()

Parameters : The method does not take any parameters.

Return Value: The method returns a hash code integer value for this object, which is equal to the uncomplicated primitive integer value, represented by this Integer object.

Below programs illustrate the use of hashCode() of Integer class:
Program 1: When integer data type is passed.






// Java program to demonstrate working
// of Java.lang.Integer.hashCode() Method
import java.lang.*;
  
public class Geeks {
  
    public static void main(String[] args)
    {
        // Object s_int created
        Integer s_int = new Integer("223");
  
        // Returning a hash code value for this object 
        int hashcodevalue = s_int.hashCode();
        System.out.println("Hash code Value for object = " + hashcodevalue);
    }
}
Output:
Hash code Value for object = 223

Program 2: When String data type is passed.
Note: This causes RuntimeErrors like NumberFormatException




// Java program to demonstrate working
// of Java.lang.Integer.hashCode() Method
import java.lang.*;
  
public class Geeks {
  
    public static void main(String[] args)
    {
        // object s_int created
        Integer s_int = new Integer("gfg");
  
        // Returning a hash code value for this object.
        int hashcodevalue = s_int.hashCode();
        System.out.println("Hash code Value for object = " + hashcodevalue);
    }
}

Output:

Exception in thread "main" java.lang.NumberFormatException: For input string: "gfg"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:580)
    at java.lang.Integer.(Integer.java:867)
    at Geeks.main(Geeks.java:9)

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