Do While Loop Java

Java Programming

A do-while loop in Java is a control flow statement that allows you to repeatedly execute a block of code as long as a certain condition is true. Unlike a regular while loop, which evaluates the condition at the beginning, a do-while loop evaluates the condition at the end of each iteration, ensuring that the block of code is executed at least once.

Personally, I find do-while loops to be very useful in situations where I want to execute a piece of code first and then check the condition later. It provides a great way to ensure that a certain action is performed at least once, regardless of the condition.

Syntax

The syntax of a do-while loop in Java is as follows:


do {
    // code to be executed
} while(condition);

The code block is enclosed within curly braces and is executed repeatedly as long as the condition remains true. The condition is checked after each iteration, and if it evaluates to true, the loop continues. If the condition evaluates to false, the loop is terminated and the program moves on to the next statement.

An important thing to keep in mind when using a do-while loop is to ensure that the condition is eventually false, otherwise you may end up in an infinite loop.

Example

Let’s say we want to prompt the user to enter a number between 1 and 10, and keep asking until a valid input is given:


import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int number;

        do {
            System.out.print("Enter a number between 1 and 10: ");
            number = input.nextInt();
        } while (number < 1 || number > 10);

        System.out.println("Valid input: " + number);
    }
}

In this example, the do-while loop keeps asking the user to enter a number between 1 and 10 until a valid input is given. The loop will continue as long as the condition (number < 1 || number > 10) remains true.

Conclusion

Do-while loops in Java are a powerful tool to control the flow of your program. They allow you to execute a block of code at least once, and then check the condition for further iterations. It’s important to ensure that the condition eventually becomes false to avoid infinite loops. I personally find do-while loops to be a useful construct in my programming journey, and I hope you do too!