4 Best Ways To Swap Two Numbers in Java without using temporary/Third variable?

A quick guide to how to swap two numbers in java. Exploring the different ways to swapping without using temporary variable.

In this tutorial, We will discuss how to swap two numbers in Java without using temporary variable.

This is very common interview question for freshers or 1-2 experience.

First, we will see how to swap using two numbers with using temporary variable then next without third variable.

Sum of  Two Numbers in Java

1. Way 1 Swap With Temp variable:

package com.adeepdrive.swap.numbers;

public class SwapTwoNumbers {
    public static void main(String[] args) {
        int a = 10, b = 20;
        System.out.println("Way 1 Before swaping using temp variable a = " + a + ", b = " + b);
        int temp;
        temp = a;
        a = b;
        b = temp;
      System.out.println("After swaping using temp variable a = " + a + ", b = " + b);
    }
}

Output:

Before swaping using temp variable a = 10, b = 20
After swaping using temp variable a = 20, b = 10


Explanation:

Here, first stored a value in temp variable. Now values will as below.

temp = 10
a = 10
b = 20

Second, we did a = b;

temp = 10
a = 20
b = 20

Then next, b = temp; which temp holds 10, putting into now b varaible.

temp = 10
a = 20
b = 10

That's all.

We will learn now swapping without using Temp variable.

2. Way 2, Way 3 Using '+', '-' operators:

package com.adeepdrive.swap.numbers;

public class SwapTwoNumbers {
    public static void main(String[] args) {
        int a = 10, b = 20;
        System.out.println("Way 2 Before swaping with '+', '-' operators: a = " + a + ", b = " + b);
        a = a + b;
        b = a - b;
        a = a - b;
        System.out.println("After swaping with '+', '-' operators: a = " + a + ", b = " + b);

        int x = 10, y = 20;
        System.out.println("Way 3 Before swaping with '+', '-' operators: a = " + x + ", b = " + y);
        x = x - y;
        y = x + y;
        x = y - x;
        System.out.println("After swaping with '+', '-' operators: a = " + x + ", b = " + y);
    }
}

Swapping two numbers in C

Output:

Way 2 Before swaping with '+', '-' operators: a = 10, b = 20
After swaping with '+', '-' operators: a = 20, b = 10
Way 3 Before swaping with '+', '-' operators: a = 10, b = 20
After swaping with '+', '-' operators: a = 20, b = 10


a = 10, b = 20
a = a + b; --> a = 30, b = 20
b = a - b; --> a = 30, b = 10
a = a - b; --> a = 20, b  10

x = 10, y = 20
x = x - y; --> x = -10, y = 20
y = x + y; --> x = -10, y = 10
x = y - x; --> x = 20, y = 10

3. Way 4 Using '*', '/' operators:

package com.adeepdrive.swap.numbers;

public class SwapTwoNumbersMultiplyu {
    public static void main(String[] args) {
        int a = 10, b = 20;
        System.out.println("Before swaping with '*', '/' operators: a = " + a + ", b = " + b);
        a = a * b; // a = 200 b = 20
        b = a / b; // a = 200 b = 10 
        a = a / b; // a = 20 b = 10
        System.out.println("After swaping with '*', '/' operators: a = " + a + ", b = " + b);
    }
}

Output:

Way 4 Before swaping with '*', '/' operators: a = 10, b = 20
After swaping with '*', '/' operators: a = 20, b = 10

a = 10, b = 20
a = a * b; --> a = 200 b = 20
b = a / b; --> a = 200 b = 10
a = a / b; --> a = 20 b = 10

Please leave your questions in comments section.
       

Swap Two Numbers in Java