Table of Contents

Overview

In this tutorial, we will learn the do-while loop statement. In this loop statement, the loop condition is checked at the end of the loop.

Java while Loop

https://www.testingdocs.com/java-while-loop-statement/

do while Loop

This loop checks the loop condition after executing the loop statements. (post-check loop control). The loop statements will execute at least once even if the loop condition evaluates to false.

The do-while loop is guaranteed to execute the loop statements at least once. So, this loop is ideal for menu-based user programs. We can display the application menu in the loop and let the user decide the flow of the program.

do
{
// loop Statements
}
while(boolean loop condition);

Example

In the below example, we will use a do-while loop to display a menu to the user. The program takes actions based on the user input to the program.

public class DoWhileLoopDemo {
 
 public static void main(String[] args) {
 int choice = 0;
 Scanner keypad = new Scanner(System.in);
 do {
 System.out.println("--- Menu ---");
 System.out.println("1.Task1");
 System.out.println("2.Task2");
 System.out.println("3.QUIT");
 System.out.println("Enter choice:");
 choice = keypad.nextInt();
 if(choice == 1)
 System.out.println("Perform Task1 
for user.");
 if(choice == 2)
 System.out.println("Perform Task2 
for user.");
 }while(choice == 1 || choice == 2);
 }
}

Java Do While Loop

Sample Program Output

— Menu —
1.Task1
2.Task2
3.QUIT
Enter choice:
1
Perform Task1 for user.
— Menu —
1.Task1
2.Task2
3.QUIT
Enter choice:
2
Perform Task2 for user.
— Menu —
1.Task1
2.Task2
3.QUIT
Enter choice:
3

The loop will run many times as per the user’s choice. The loop will run if the user choice is 1 or 2. The loop will terminate for any other user option.

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