Do While Loop Example in Java

Introduction

Do While Loop is a classic Java console program that demonstrates the concept with complete source code and sample output. Loops repeat work until a condition is met — essential for processing collections and numeric ranges.

This tutorial walks through the program line by line, explains how the logic works, and highlights best practices you can apply in your own code.

Definition

A loop is a sequence of statements which is specified once but which may be carried out several times in succession. The code “inside” the loop (the body of the loop, shown below as xxx) is obeyed a specified number of times, or once for each of a collection of items, or until some condition is met, or indefinitely. The do while construct consists of a process symbol and a condition. First, the code within the block is executed, and then the condition is evaluated. If the condition is true the code within the block is executed again. This repeats until the condition becomes false.

Syntax

do {
	//Statements
} while (Condition);

Do While Loop Example Program

class DoWhileLoopExample{
	public static void main(String[] args){
		int num=0;
		do{
			System.out.println(""+num);
			num++;
		}while(num<=5);
	}
}

Sample Output

0
1
2
3
4
5

When to use

Use this do while loop example when learning or revising core Java syntax.

How it works

1. Execution begins in the main method — the JVM calls this method when you run the class.

2. int num=0; updates a variable used in the calculation or output.

3. A println / print call writes text to the console — part of the sample output below.

4. A loop repeats the block until its condition becomes false.

5. Compare your console output with the sample output for Do While Loop to confirm the program behaves correctly.

Best Practices

• Use meaningful variable and class names that describe their purpose.
• Compile and run the program locally — modify values to see how output changes.
• Read compiler errors carefully; they usually point to the exact line to fix.

Common Mistakes

• Copying code without understanding each line — practice by changing one statement at a time.
• Mismatching the public class name and the .java filename.
• Forgetting semicolons at the end of statements.