When it comes to control flow in Java programming, the do while loop is a powerful tool that allows you to repeatedly execute a block of code until a condition is no longer true. In this article, I’ll dive deep into the details of the do while loop and showcase its capabilities.
First, let’s start with the syntax of the do while loop in Java:
do {
// code block to be executed
} while (condition);
One important thing to note about the do while loop is that it will always execute the code block at least once, regardless of whether the condition is initially true or false. This makes it particularly useful when you want to ensure that a certain block of code is executed before checking the condition.
Now, let’s explore a real-world example to better understand the practical application of the do while loop. Suppose we want to create a program that prompts the user to enter a positive number, and keeps asking until the user enters a valid input.
import java.util.Scanner;
public class PositiveNumber {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int number;
do {
System.out.print("Enter a positive number: ");
number = scanner.nextInt();
} while (number <= 0);
System.out.println("You entered: " + number);
}
}
In this example, the do while loop ensures that the prompt for a positive number is shown to the user at least once, and then checks if the entered number is less than or equal to zero. If the condition is true, the loop continues and repeats the prompt until a positive number is entered. Once a positive number is entered, the loop terminates and the program displays the input.
It's important to note that the do while loop is particularly useful when you want to perform an action first, and then check the condition for continuing the loop. This is different from the while loop, where the condition is checked before the code block is executed.
Conclusion
The do while loop is a powerful construct in Java that allows you to execute a block of code repeatedly until a condition is no longer true. It guarantees that the code block is executed at least once, making it useful in situations where you want to ensure that a certain action is performed before checking the condition. By understanding the syntax and practical applications of the do while loop, you can enhance your Java programming skills and write more efficient code.