Java Do-While Loop

do-while

Exercises Interview question Video Tutorial Discussion

The do-while loop in Java is a control flow statement that allows you to execute a block of code at least once, and then repeatedly as long as a specified condition remains true. This loop is unique because it checks the condition after running the code block, guaranteeing at least one execution.

Syntax:

do {
    // Code to execute
} while (condition);

How It Works

The code inside the do block runs first.

After the block executes, the condition is checked.

If the condition is true, the loop repeats.

If the condition is false, the loop stops.

Example: Print Numbers 1 to 5

public class DoWhileLoop {
    public static void main(String[] args) {
        int i = 1;
        do {
            System.out.println(i);
            i++;
        } while (i <= 5);
    }
}

Output:

Key Points

The do block always executes at least once, even if the condition is false from the start.

The condition is checked after the code block runs.

Useful when you want the loop to run at least one time, such as when displaying a menu or asking for user input.

When to Use do-while

When you need guaranteed execution of the code at least once.

When the condition to repeat depends on something that happens inside the loop.

Tips: Use the do-while loop for scenarios like input validation, menu-driven programs, or repeating actions that must happen at least once.