Do–while loop in Java - Mini Project: Build & Apply

Do-while loop

📖 Scenario: Imagine you are creating a simple program that asks a user to enter a number repeatedly until they enter zero. This is like asking a friend to keep telling you numbers until they say "stop" by entering zero.

🎯 Goal: Build a Java program that uses a do-while loop to keep asking the user for numbers and stops when the user enters zero.

📋 What You'll Learn

Use a do-while loop to ask for input at least once

Use a variable called number to store the user input

Stop the loop when number is zero

Print each entered number except zero

💡 Why This Matters

🌍 Real World

Do-while loops are useful when you want to run a task at least once and then repeat it based on user input or a condition, like menus or input validation.

💼 Career

Understanding loops and user input is essential for many programming jobs, including software development, data processing, and automation.

1

Create a variable to store the number

Create an integer variable called number and set it to -1.

Java

int number = -1;  // Your code here

Need a hint?

Use int number = -1; to create the variable.

2

Set up a Scanner to read user input

Create a Scanner object called scanner to read input from System.in.

Java

int number = -1;
Scanner scanner = new Scanner(System.in);  // Your code here

Need a hint?

Use Scanner scanner = new Scanner(System.in); to read input.

3

Write the do-while loop to read numbers

Write a do block that asks the user to enter a number using System.out.println, reads the number into number using scanner.nextInt(), and prints the number if it is not zero. Then write the while condition to continue the loop while number is not zero.

Java

import java.util.Scanner;

int number = -1;
Scanner scanner = new Scanner(System.in);

// Your do-while loop here

Need a hint?

Use do { ... } while (number != 0); and inside the block read and print the number.

4

Print a goodbye message after the loop ends

After the do-while loop, write a System.out.println statement to print "Goodbye!".

Java

import java.util.Scanner;

int number = -1;
Scanner scanner = new Scanner(System.in);

do {
    System.out.println("Enter a number (0 to stop):");
    number = scanner.nextInt();
    if (number != 0) {
        System.out.println("You entered: " + number);
    }
} while (number != 0);

// Your print statement here

Need a hint?

Use System.out.println("Goodbye!"); after the loop.