The while Loop and do-while Loop0%

The Standard for Loop and Decrement Counters

The while Loop and do-while Loop

Beginner12 min read•Updated: 2026-10-22

🔄 The while and do-while Loops in Java

Introduction

Loops automate repetitive operations. Java provides entry-controlled loops (while) and exit-controlled loops (do-while).

🔁 1. The `while` Loop (Entry-Controlled)

Condition is evaluated before executing the loop body:

1public class WhileDemo {
2    public static void main(String[] args) {
3        int count = 1;
4        int sum = 0;
5 
6        while (count <= 10) {
7            sum += count;
8            count++;
9        }
10 
11        System.out.println("Sum of 1 to 10: " + sum);
12    }
13}

🔁 2. The `do-while` Loop (Exit-Controlled)

Guaranteed to execute at least once because the condition is checked at the end:

1import java.util.Scanner;
2 
3public class DoWhileDemo {
  public static void main(String[] args) {
      Scanner scanner = new Scanner(System.in);
      int pin;
      final int CORRECT_PIN = 4321;
8 
      do {
          System.out.print("Enter 4-digit Security PIN: ");
          pin = scanner.nextInt();
          if (pin != CORRECT_PIN) {
              System.out.println("Incorrect PIN. Please re-enter.");
          }
      } while (pin != CORRECT_PIN);
16 
      System.out.println("Authentication Successful!");
      scanner.close();
  }
20}

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The Standard for Loop and Decrement Counters

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The Standard for Loop and Decrement Counters

The while Loop and do-while Loop

Beginner12 min read•Updated: 2026-10-22

Study Materials

🔄 The while and do-while Loops in Java

Introduction

Loops automate repetitive operations. Java provides entry-controlled loops (while) and exit-controlled loops (do-while).

🔁 1. The `while` Loop (Entry-Controlled)

Condition is evaluated before executing the loop body:

1public class WhileDemo {
2    public static void main(String[] args) {
3        int count = 1;
4        int sum = 0;
5 
6        while (count <= 10) {
7            sum += count;
8            count++;
9        }
10 
11        System.out.println("Sum of 1 to 10: " + sum);
12    }
13}

🔁 2. The `do-while` Loop (Exit-Controlled)

Guaranteed to execute at least once because the condition is checked at the end:

1import java.util.Scanner;
2 
3public class DoWhileDemo {
  public static void main(String[] args) {
      Scanner scanner = new Scanner(System.in);
      int pin;
      final int CORRECT_PIN = 4321;
8 
      do {
          System.out.print("Enter 4-digit Security PIN: ");
          pin = scanner.nextInt();
          if (pin != CORRECT_PIN) {
              System.out.println("Incorrect PIN. Please re-enter.");
          }
      } while (pin != CORRECT_PIN);
16 
      System.out.println("Authentication Successful!");
      scanner.close();
  }
20}

Next Lesson

The Standard for Loop and Decrement Counters

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Menu-Driven Console Application Logic	The Standard for Loop and Decrement Counters

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next

🔄 The while and do-while Loops in Java

Introduction

🔁 1. The while Loop (Entry-Controlled)

🔁 2. The do-while Loop (Exit-Controlled)

The Standard for Loop and Decrement Counters

Related Lessons

Practice Quiz

Loading Page Content...

🔄 The while and do-while Loops in Java

Introduction

🔁 1. The while Loop (Entry-Controlled)

🔁 2. The do-while Loop (Exit-Controlled)

The Standard for Loop and Decrement Counters

Related Lessons

Practice Quiz

🔁 1. The `while` Loop (Entry-Controlled)

🔁 2. The `do-while` Loop (Exit-Controlled)

🔁 1. The `while` Loop (Entry-Controlled)

🔁 2. The `do-while` Loop (Exit-Controlled)