Swap Two Numbers In Java: Welcome to All of you another simple java program for beginners series of posts. In this tutorial, we’ll talk about how to swap two numbers in various ways. But before that, if you are not aware of what is Swapping then let me share with you “Swapping is nothing but interchange values of the variables”.
For example, let’s take two numbers here we’ll say int a=5 and int B=4. Now what I mean by swap is after executing the swapping program code when I print the value of A, it should print the value of A as 4, and then when I print the value of B it will print 5.
| Post Type: | Java Programs Tutorial |
| Published On: | www.softwaretestingo.com |
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Different Ways to Swap Two Numbers In Java
We can Swap Two Numbers In Java in different ways and those ways are:
- Swap two numbers by using the third variable
- Swap two numbers without using a third variable (+ and -)
- Swap two numbers without using their variable (Bitwise XOR operator)
- Swap two numbers without using their variable ( * and /)
- Single Statement
Swap Two Numbers by Using the Third Variable
package com.softwaretestingo.basic;
public class SwapNumbersEx1
{
public static void main(String[] args)
{
int a=5;
int b=4;
System.out.println("Before Swap the Value Of A & B: "+a+" "+b);
int temp;
temp=a; // temp=5
a=b; //a=4;
b=temp; //b=5
System.out.println("After Swap the Value Of A & B: "+a+" "+b);
}
}
Now before assigning the value of B to A, we’ll assign that value of A to a variable called temp. And then once you got the value of A into the Temp variable you can assign the value of B to A. After that, you can assign the temp variable value to B.
But if you focus on this code the amount of memory we should be using is only eight bytes. But unfortunately, we are creating one more variable just for the swapping which means we are wasting extra memory. And to save this memory instead of going for the third variable we’ll use will use some other logic.
Swap Two Numbers Without Using Third Variable ( + and -)
package com.softwaretestingo.basic;
public class SwapNumbersEx2
{
public static void main(String[] args)
{
int a=5;
int b=4;
System.out.println("Before Swap the Value Of A & B: "+a+" "+b);
a = a+b;
b = a-b;
a = a-b;
System.out.println("After Swap the Value Of A & B: "+a+" "+b);
}
}
Let’s say how it works first so initially, the value of A is five and B is four which means when you say the new value for A will be nine right and then the value of B is still four. When the second statement got executed (b = a-b) that means B is nine minus four and B becomes five.
In this code, the value of A is nine and your B value is five so when you execute this statement (a = a-b;) the value of A becomes four and you can see we have swapped the number. now if you as you can see here we are not wasting extra any variables and that’s the advantage of using logic.
If we can focus on the binary conversion of 5 as 1 0 1 and the binary conversion of four as 1 0 0 which means to represent the numbers five and four we require only three bits but during the operation, the value of A becomes nine and the binary format of nine is 1 0 0 1. That means that in the course of the operation your result will go from 3 bits to 4 bits.
Swap Two Numbers Without Using Third Variable – Bitwise XOR (^) operator
To implement this logic what we’ll do is instead of this plus sign we’ll use the Bitwise XOR (^) operator. So how this bitwise operator is working is If both bits are the same then the result will be 0 and if there is a mismatch in the bits then the result will be 1. You can also follow the below table.
| A | B | A XOR B |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
So when we run the program
package com.softwaretestingo.basic;
public class SwapNumbersEx3
{
public static void main(String[] args)
{
int a=5;
int b=4;
System.out.println("Before Swap the Value Of A & B: "+a+" "+b);
//^ -> XOR 1 1 -> 0, 1 0 -> 1, 0 0 -> 0, 0 1 -> 1
a = a^b; // 1 0 1 XOR 1 0 0 -> 0 0 1
b = a^b; // 0 0 1 XOR 1 0 0 -> 1 0 1 ->5
a = a^b; // 0 0 1 XOR 1 0 1 ->1 0 0 ->4
System.out.println("After Swap the Value Of A & B: "+a+" "+b);
}
}
Swap Two Numbers Without Using Third Variable ( * and /)
In This way, we will see how to swap two variables’ values without using the third variable but we are taking the help of the multiplication and division operator. But here we have one condition is the value of a and b should not be Zero.
package com.softwaretestingo.basic;
public class SwapNumbersEx4
{
public static void main(String[] args)
{
int a=5;
int b=4;
System.out.println("Before Swap the Value Of A & B: "+a+" "+b);
a = a*b;
b = a/b;
a = a/b;
System.out.println("After Swap the Value Of A & B: "+a+" "+b);
}
}
Note: If any of the variables have the value Zero then you will get the arithmetic exception.
Swap Two Numbers Using Single Statement
package com.softwaretestingo.basic;
public class SwapNumbersEx5
{
public static void main(String[] args)
{
int a=5;
int b=4;
System.out.println("Before Swap the Value Of A & B: "+a+" "+b);
b=a+b -(a=b);
System.out.println("After Swap the Value Of A & B: "+a+" "+b);
}
}
Let me explain to you how this will work. As you know the execution always starts from right to left.
- Here (a=b) means the B value will be assigned to A. So the current value of A is 4.
- a+b: means the total value becomes 9.
- b=a+b -(a=b): b=9-4; so finally the value of b is 5
Already the value of A changed to 4. So finally the value of A=4 and B=5.
Conclusion:
Finally, we have reached to end of the simple java program for beginners series of posts. In this blog post, we have discussed 5 different ways how to swap two numbers. I hope this blog post helps you in give a better understanding of how to do that. If still you have any concerns then let us know in the comment section.
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