Do while loop Java

Aashutosh Dwivedi3 Apr, 2026

While a standard while loop checks the condition first, the do while loop Java flips this logic. It executes the code block before evaluating the condition. If you are building a menu-driven program or a game where a player must take at least one turn, this loop is your best friend. This guide explores the do while loop Java syntax and provides a clear do while loop Java program to help you distinguish it from other looping structures in Data Structures and Algorithms (DSA).

What is a Do While Loop in Java?

The do while loop Java is a variant of the while loop. The main difference lies in the timing of the condition check. In a standard loop, the condition is a "pre-test." In this version, it is a "post-test."

Do While Loop Java Syntax

The structure of this loop ensures the code block runs immediately upon reaching it. Notice the placement of the while keyword at the very end. Java do { // code block to be executed } while (condition);

Do: This keyword marks the start of the code block.
Code Block: This section executes immediately without any initial check.
Condition: After the first run, Java evaluates this boolean expression. If true, it loops back to do. If false, it exits.

Crucial Syntax Note: Unlike the standard while loop, the do while loop Java syntax requires a semicolon (;) after the while condition.

Do While Loop Java Example

Let's take a look at a basic do while loop Java example. We want to print numbers, but we want to ensure it runs even if we are "out of bounds" from the start. Java int count = 6; do { System.out.println("Current count is: " + count); count++; } while (count < 5); What happens here?

The variable count starts at 6.
The program enters the do block and prints "Current count is: 6".
count increments to 7.
The condition 7 < 5 is checked. Since this is false, the loop stops.

If this were a standard while loop, nothing would have printed at all. This "run-first" behaviour is the hallmark of the do while loop Java. Also Read :

Do While Loop Java Program: User Input Scenario

In professional development, a common do while loop Java program involves handling user input. For instance, you might want to ask a user for a number until they enter a negative one to quit. Java import java.util.Scanner; public class InputExample { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int number; do { System.out.print("Enter a positive number (or a negative one to exit): "); number = sc.nextInt(); System.out.println("You entered: " + number); } while (number >= 0); System.out.println("Loop terminated."); } } This makes sure the user sees the prompt at least once, which makes more sense than trying to check the number before they’ve even had a chance to enter it.

While Loop Vs Do While Loop: Comparison

Choosing between a while loop and a do while loop Java depends entirely on your specific logic requirements. Deciding between these two can be tricky. Think of it like a security check: one asks for your ID before you enter the building, while the other lets you in first and asks for your ID on the way out.

Feature	While Loop	Do While Loop
Logic Style	"Look before you leap"	"Leap before you look"
First Impression	Checks the condition first	Runs the code first
Minimum Runs	Might not run even once	Guaranteed to run at least once
Ending Syntax	Ends with a curly brace }	Ends with a semicolon ;
Perfect For	Standard data processing	Interactive menus and user prompts

Common Mistakes to Avoid in Do while Loop

Missing Semicolons: Forgetting the semicolon after while(condition); is the most frequent error. Your code will not compile without it.
Infinite Loops: Just like other loops, if your condition never becomes false, the do while loop Java will run forever. Always update your variables inside the do block.
Logic Errors: Remember that the first iteration happens regardless of whether the condition is true. Never use this loop for tasks that require a strict security check before any action is taken.