Swap two numbers without using third or temporary variable in java

Swap two numbers without using temporary variable:

• Method 1: Swap numbers using XOR method.

• Method 2: Swap numbers using addition & subtraction.

• Method 3:Swap numbers using multiplication & division.

 Swap two numbers – XOR method

Suppose, we would like swap two variables x = 4 & y = 7 using XOR method.
Truth table of “Exclusive-OR” or XOR gate is :

• We will swap variables using XOR (x = 4 & y = 7)
  1. Initially x = 4 & y = 7
  2. x = x ^ y  = 3
     • i.e.  x = 4 ^ 7 = 0100 ^ 0111 = 0011 = 3
  3. x = 3 & y = 7
  4. y = x ^ y = 4
     • i.e. y = 3 ^ 7 = 0011 ^ 0111 = 0100 = 4
  5. x = 3 & y = 4
  6. x = x ^ y = 7
     • i.e. x = 3 ^ 4 = 0011 ^ 0100 = 0111 = 7
  7. x = 7 & y = 4

Swap two numbers – addition & subtraction method in java

1. Swap two variables (x = 4 & y = 7) using addition & subtraction.
2. Initially x = 4 & y = 7
3. x = x + y = 11
   • x  = 4 + 7 = 11.
4. x = 11, y  = 7
5. y = x – y = 4
   • y = 11 – 7 = 4
6. x = 11, y = 4
7. x = x – y = 7
   • x = 11 – 4 = 7.
8. After swap x = 7 & y = 4

 Swap two numbers using multiplication & division in java

1. Swap two variables (x = 4 & y = 7) using multiplication & division
2. Initially x = 4 & y = 7
3. x = x *  y = 28
   • x  = 4 * 7 = 28.
4. x = 28, y  = 7
5. y = x / y = 4
   • y = 28 / 7 = 4
6. x = 28, y = 4
7. x = x / y = 7
   • x = 28 / 4 = 7.
8. After swap x = 7 & y = 4

Code: Swap two numbers without temporary variable (java)

package org.learn;

import java.util.Scanner;

public class DemoSwap {

	public static void main(String[] args) {

		try (Scanner scanner = new Scanner(System.in)) {
			System.out.printf("1. Enter first number x : ");
			int x = scanner.nextInt();
			System.out.printf("2. Enter second number y : ");
			int y = scanner.nextInt();

			swapUsingXOR(x, y);
			swapUsingAdditionAndSubstraction(x, y);
			swapUsingMultiplicationAndDivision(x, y);
		}
	}
	
	private static void swapUsingXOR(int x, int y) {
		// swapping number using XOR
		// x = 4 & y = 7
		// x ^ y = 0100 ^ 0111 = 0011 = 3
		// x becomes 3
		x = x ^ y;

		// x ^ y = 0011 ^ 0111 = 0100 = 4
		// y become 4
		y = x ^ y;

		// x ^ y = 0011 ^ 0100 = 0111 = 7
		// x becomes 7
		x = x ^ y;

		System.out.printf("3. Swap numbers by XOR : x = %d, y = %d ",x,y);
	}
	
	private static void swapUsingAdditionAndSubstraction(int x, int y) {
		// x = 4 & y = 7
		// x = 4 + 7 = 11
		// x becomes 11
		x = x + y;

		// x = 11 & y = 7
		// y = 11 - 7 = 4
		// y becomes 4
		y = x - y;

		// x = 11 & y = 4
		// x = 11 - 4 = 7
		// x becomes 7
		x = x - y;

		System.out.printf("\n4. Swap using Addition & subtraction: x = %d, y = %d ",x,y);
	}

	private static void swapUsingMultiplicationAndDivision(int x, int y) {
		// x = 4 & y = 7
		// x = 4 * 7 = 28
		// x becomes 11
		x = x * y;

		// x = 28 & y = 7
		// y = 28 / 7 = 4
		// y becomes 4
		y = x / y;

		// x = 28 & y = 4
		// x = 28 / 4 = 7
		// x becomes 7
		x = x / y;

		System.out.printf("\n5. Swap using multiplication & division: x = %d, y = %d ",x,y);
	}	
}

Output: swap two variables without third variable in java

1. Enter first number x : 4
2. Enter second number y : 7
3. Swap numbers by XOR : x = 7, y = 4 
4. Swap using Addition & subtraction: x = 7, y = 4 
5. Swap using multiplication & division: x = 7, y = 4