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Java do while loop

Published on August 3, 2022
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By Pankaj
Developer and author at DigitalOcean.
Java do while loop

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Java do-while loop is used to execute a block of statements continuously until the given condition is true. The do-while loop in Java is similar to while loop except that the condition is checked after the statements are executed, so do while loop guarantees the loop execution at least once.

Java do while loop

Java do while loop syntax is as follows:

do {
     // statements
} while (expression);

The expression for the do-while loop must return a boolean value, otherwise, it will throw compile-time error.

do while java flow diagram

Java Do While Loop

Java do-while loop example

Here is a simple java do-while loop example to print numbers from 5 to 10.

package com.journaldev.javadowhileloop;

public class JavaDoWhileLoop {

	public static void main(String[] args) {

		int i = 5;
		do {
			System.out.println(i);
			i++;
		} while (i <= 10);
	}
}

java do while loop example

do while true java

We can create an infinite loop by passing boolean expression as true in the do while loop. Here is a simple do while java infinite loop example.

package com.journaldev.javadowhileloop;

public class DoWhileTrueJava {

	public static void main(String[] args) throws InterruptedException {
		do {
			System.out.println("Start Processing inside do while loop");
			// look for a file at specific directory
			// if found, then process it, such as inserting rows into database
			System.out.println("End Processing of do while loop");

			Thread.sleep(5 * 1000);
		} while (true);
	}
}

Note that you will have to manually quit the application to stop it, using Ctrl+C if the program is executed in the terminal. If you execute the program in Eclipse IDE then there is a red color button to terminate the program.

do while vs while loop

The only time you should use a do-while loop is when you want to execute the statements inside the loop at least once, even though condition expression returns false. Otherwise, it’s always better to use a while loop. Java while loop looks cleaner than a do-while loop. That’s all for java do while loop. You should also look into java for loop and java continue statement. Reference: Oracle Documentation

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Pankaj

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Developer and author at DigitalOcean.

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JournalDev
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August 29, 2020

import java.util.*; public class accepting { public static void main(String[] args) { //accept System.out.println (“Programe to accept your name”); Scanner sc = new Scanner(System.in); System.out.print("Enter Fullname : "); String fullname = sc.nextLine(); System.out.print("Enter Lastname : "); String lastname = sc.nextLine(); System.out.print("Enter Nickname : "); String nickname = sc.nextLine(); System.out.print(“Enter Student ID : “); String id = sc.nextLine(); //output System.out.println (”\n” + fullname + " " + lastname + " " + nickname + " " + id); } }

- VARAPON YUSOP

    JournalDev
    DigitalOcean Employee
    DigitalOcean Employee badge
    December 26, 2019

    The image still displays the wrong arrow…

    - Roman

      JournalDev
      DigitalOcean Employee
      DigitalOcean Employee badge
      February 25, 2019

      please give syntax for do while loop

      - rupesh

        JournalDev
        DigitalOcean Employee
        DigitalOcean Employee badge
        February 7, 2019

        hi Pankaj, Can you please correct the “if condition is true arrow” in the image?

        - Nikhil

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