Java Program to Swap Two Numbers

Program 1: Using Scanner class

 //importing java package
import java.util.Scanner;

 public class SwapTwoNumbers{
  public static void main (String [] args){

     //creating new Scanner
    Scanner sc = new Scanner (System.in);

     System.out.println ("Please enter first number:\n");
    int num1 = sc.nextInt();
    System.out.println ("Please enter second number:\n");
    int num2 = sc.nextInt();

     System.out.println ("*** Before Swapping ***\n");
    System.out.println ("First number: "+num1);
    System.out.println ("Second number: "+num2);

    int num3 = num1;
    num1 = num2;
    num2 = num3;

     System.out.println ("*** After Swapping ***\n");
    System.out.println ("First number: "+num1);
    System.out.println ("Second number: "+num2);
  }
}

Save this file as 'SwapTwoNumbers.java'
Compile: $javac SwapTwoNumbers.java
Execute: $java SwapTwoNumbers
Output:

 Please enter first number:

 20
Please enter second number:

 30
*** Before Swapping ***

 First number: 20
Second number: 30
*** After Swapping ***

 First number: 30
Second number: 20


Program 2: Using BufferedReader class


//importing java packages
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class SwapTwoNumbers1{
  public static void main (String [] args)
  throws IOException{
    //creating new BufferedReader
    BufferedReader br = new BufferedReader (new InputStreamReader (System.in));

    System.out.println ("Please enter first number:\n");
    int num1 = Integer.parseInt (br.readLine());
    System.out.println ("Please enter second number:\n");
    int num2 = Integer.parseInt (br.readLine());

    System.out.println ("*** Before Swapping ***\n");
    System.out.println ("First number: "+num1);
    System.out.println ("Second number: "+num2);

    int num3 = num1;
    num1 = num2;
    num2 = num3;

    System.out.println ("*** After Swapping ***\n");
    System.out.println ("First number: "+num1);
    System.out.println ("Second number: "+num2);
  }
}

Save this file as 'SwapTwoNumbers1.java'
Compile: $javac SwapTwoNumbers1.java
Execute: $java SwapTwoNumbers1
Output:

Please enter first number:

40
Please enter second number:

60
*** Before Swapping ***

First number: 40
Second number: 60
*** After Swapping ***

First number: 60
Second number: 40