Tutorials

Java Basic Programs


Java Swap Program


In this chapter of the java programming tutorial, we are going to write a simple java program to:

  • swap two numbers using third variable
  • swap two numbers without using third variable

Java Program to Swap Numbers using 3rd variable

package BasicPrograms;

public class TihSwapVariable {

	public static void main(String[] args) {
		int a = 101;
		int b = 201;
		int c;  //using third variable
		
		System.out.println("Before swap a="+ a+ " b="+ b);
		
		//Swap operation
		c = b;
		b = a;
		a = c;
		
		System.out.println("After swap a="+ a+ " b="+ b);				

	}

}

OUTPUT

Before swap a=101 b=201
After swap a=201 b=101
 
Calculation logic
a=101, b=201
c=201
b=101
a=201
Thus we get, a=201, b=101
 

Java program to swap two numbers

Given below is a java program to swap two numbers without using third variable.

package BasicPrograms;

public class TihSwap {

	public static void main(String[] args) {
		int a = 101;
		int b = 201;
		System.out.println("Before swap a="+ a+ " b="+ b);
		
		//swap variables 
		a = a - b;
		b = a + b;
		a = b - a;
		
		System.out.println("After swap a="+ a+ " b="+ b);

	}

}

OUTPUT

Before swap a=101 b=201
After swap a=201 b=101
 

Calculation logic

a=101, b=201

a = 101 - 201 = -100    [a=a-b]

In the following statement, the value of a will be -100

b = -100 + 201 = 101   [b=a+b]

In the following statement, the value of b will be 101

a = 101 - (-100) = 201  [a=b-a]

 

Thus we get, a=201, b=101

 



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