Difference between While and Do While in Java

In this article we will show you, What are the difference between While and Do While in Java Programming Language with practical example.

Difference between While and Do While in Java

Although Do While loop and While loop looks similar but they differ in the order of execution.

• In Java While loop, condition is tested at the beginning of the loop and if the condition is True then only statements in that loop will be executed. So, While loop executes the code block only if the condition is True.
• In Java Do While loop, condition is tested at the end of the loop so Do While executes the statements in the code block at least once even if the condition Fails.

May be you are confused, I think you will understand it better when you see the example. Lets write the same program using While loop and Do While loop to understand the order of execution.

Java While loop example

In this Java program we are declaring integer variable Number and assigned value zero to it. Next, We will check whether Number (value = 0) is greater than 10 or not to deliberately fail the condition. There is one more System.out.println statement outside the While loop and this statement will be executed after the while loop.

JAVA CODE

package Loops;

public class WhileLoop {
	
	public static void main(String[] args) {
		int number = 0;
		
		while (number > 10)  {
			System.out.println("Number is Greater Than 10");
		}
		System.out.println("This Statement is Coming from Outside of while loop");
	}
}

OUTPUT

Java Do While Loop example

In this Java program, We are going to write the same example using Java Do while loop

JAVA CODE

package Loops;

public class DoWhileDiff {
	
	public static void main(String[] args) {
		int number = 0;
		
		do {
			System.out.println("Number is Greater Than 10");
		}while (number > 10);
		System.out.println("This Statement is Coming from Outside of while loop");
	}
}

OUTPUT

Although the condition fail, statement inside the loop is executed once because the condition is tested after the execution of the statements.

We hope you understood the difference :)

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