06 August 2022

Java While and Do-While Loops with Code Examples

development

In this guide, we will delve into two fundamental types of loops in Java: the while loop and the do-while loop. We’ll explore their differences, use cases, and provide illustrative code examples to help you grasp their concepts effectively.

The While Loop

The while loop is a fundamental construct in Java that allows you to repeatedly execute a block of code as long as a certain condition remains true. It’s particularly useful when you want to execute a code block an unknown number of times based on a condition. Here’s the basic syntax of a while loop:

while (condition) {
    // Code to be executed repeatedly
}

Let’s take a look at an example to better understand how the while loop works:

public class WhileLoopExample {
    public static void main(String[] args) {
        int count = 0;
        
        while (count < 5) {
            System.out.println("Count: " + count);
            count++;
        }
        
        System.out.println("Loop finished");
    }
}

In this example, the loop will iterate as long as the count is less than 5. The count variable starts at 0 and increments with each iteration, printing the value of count until it reaches 5.

The Do-While Loop

The do-while loop is a close cousin of the while loop but with a slight difference: it guarantees that the loop’s code block will be executed at least once, regardless of the condition. The condition is checked after the execution of the loop’s code block. The syntax of a do-while loop is as follows:

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

Let’s explore a practical example of the do-while loop:

import java.util.Scanner;

public class DoWhileLoopExample {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int number;
        
        do {
            System.out.print("Enter a number (0 to exit): ");
            number = scanner.nextInt();
            System.out.println("You entered: " + number);
        } while (number != 0);
        
        System.out.println("Loop finished");
    }
}

In this example, the loop asks the user to enter a number repeatedly until they input 0. Even if the user inputs 0 on the first try, the loop’s code block will still execute once before checking the condition.

Choosing Between While and Do-While Loops

Deciding whether to use a while loop or a do-while loop depends on your specific use case. Use a while loop when you want to execute a block of code zero or more times, based on a condition. On the other hand, opt for a do-while loop when you need to ensure that the loop’s code block executes at least once before checking the condition.

Conclusion

Loops are a crucial part of programming, allowing you to automate repetitive tasks and control the flow of your code. Java’s “while” and “do-while” loops are valuable tools that provide developers with the flexibility to execute code repeatedly based on specific conditions.

06 August 2022