Swapping two numbers without using temporary variable

Very basic interview question : Swap two variables without using third or temporary variables.  This serves the purpose of getting started with the interview. There are 3 ways to do this and we will discus all of them now

1. Addition
2. XOR operation(bitwise operator)
3. Multiplication

By Addition

/**

 * Created with IntelliJ IDEA.
 * User: aniket
 * Date: 19/12/13
 * Time: 8:20 PM
 */
public class VariableSwapper {
    public static void main(String args[]){
        int a = 4;
        int b = 5;
        System.out.println("***** Swapping using Addition *****");
        System.out.println("Before Swapping a : " + a);
        System.out.println("Before Swapping b : " + b);
        a = a + b;
        b = a - b;
        a = a - b;
        System.out.println("After Swapping a : " + a);
        System.out.println("After Swapping b : " + b);
    }

}

By XOR operation

 /**
 * Created with IntelliJ IDEA.
 * User: aniket
 * Date: 19/12/13
 * Time: 8:20 PM
 */
public class VariableSwapper {

    public static void main(String args[]){

        int a = 4;
        int b = 5;
        System.out.println("***** Swapping using XOR *****");
        System.out.println("Before Swapping a : " + a);
        System.out.println("Before Swapping b : " + b);
        a = a ^ b;
        b = a ^ b;
        a = a ^ b;
        System.out.println("After Swapping a : " + a);
        System.out.println("After Swapping b : " + b);

    }

}

By Multiplication

/**
 * Created with IntelliJ IDEA.
 * User: aniket
 * Date: 19/12/13
 * Time: 8:20 PM
 */
public class VariableSwapper {

    public static void main(String args[]){

        int a = 4;
        int b = 5;

        System.out.println("***** Swapping using Multiplication *****");

        System.out.println("Before Swapping a : " + a);
        System.out.println("Before Swapping b : " + b);

        a = a * b;
        b = a / b;
        a = a / b;

        System.out.println("After Swapping a : " + a);
        System.out.println("After Swapping b : " + b);

    }

}

Output remains the same except printing the method part.

***** Swapping using Multiplication *****
Before Swapping a : 4
Before Swapping b : 5
After Swapping a : 5
After Swapping b : 4 

XOR logic can be better understood with following diagram