Java - Swap Two Numbers

In this post, you will learn how to code Java Program to Swap Two Numbers using 2 different methods.

1. Using third variable
2. Without using third variable

Java Program to Swap Two Numbers

Method 1 : using third variable

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String []args) throws IOException {

        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        System.out.println("Enter first number: ");
        int firstNumber = Integer.parseInt(br.readLine());
        System.out.println("Enter second number: ");
        int secondNumber = Integer.parseInt(br.readLine());

        //Before Swapping two numbers
        System.out.println("Before Swapping :");
        System.out.println("First number is "+firstNumber);
        System.out.println("Second number is "+secondNumber);

        //Swapping the numbers
        int temp = firstNumber;
        firstNumber = secondNumber;
        secondNumber = temp;

        //After Swapping two numbers
        System.out.println("After Swapping :");
        System.out.println("First number is "+firstNumber);
        System.out.println("Second number is "+secondNumber);
    }

}

Output:

Enter first number: 
122
Enter second number: 
222
Before Swapping :
First number is 122
Second number is 222
After Swapping :
First number is 222
Second number is 122



Method 2 : Without using third variable

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String []args) throws IOException {

        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        System.out.println("Enter first number: ");
        int firstNumber = Integer.parseInt(br.readLine());
        System.out.println("Enter second number: ");
        int secondNumber = Integer.parseInt(br.readLine());

        //Before Swapping two numbers
        System.out.println("Before Swapping :");
        System.out.println("First number is "+firstNumber);
        System.out.println("Second number is "+secondNumber);

        //Swapping the numbers without using third variable
        firstNumber = firstNumber + secondNumber;
        secondNumber = firstNumber - secondNumber;
        firstNumber = firstNumber - secondNumber;

        //After Swapping two numbers
        System.out.println("After Swapping :");
        System.out.println("First number is "+firstNumber);
        System.out.println("Second number is "+secondNumber);
    }

}

Output:

Enter first number: 
127
Enter second number: 
323
Before Swapping :
First number is 127
Second number is 323
After Swapping :
First number is 323
Second number is 127

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