while Loop in Java with Example

Last Updated: 28 May, 2022

In Java or any other programming languages, loops play an important role in executing a set of instructions multiple times based on the given condition. Inside a loop block, the set of instructions is fixed and it executes repeatedly while some condition evaluates to true.

For Example, Suppose We have to print the same message 100 times, then rather than typing the same code 100 times, we can use a loop here.

Java provides three basic types of loops:

1. for loop
2. while loop
3. do...while loop

In this tutorial we are going to discuss while loop with definition, diagram and example.

Java while Loop

Java while loop functionality is same as for loop only syntax is different it also used to run a set of instructions until a certain condition is met.

Java while loop Syntax:

while (testExpression) { // body of loop }

while Loop execution flow:

• A while loop evaluates the textExpression inside the parenthesis ().
• If the textExpression evaluates to true, the code inside the while loop is executed.
• The textExpression is evaluated again.
• This process continues until the textExpression is false.
• When the textExpression evaluates to false, the loop will be terminated.

Flowchart of Java while Loop

Example 1 : Java while Loop Program

// Java Program to demonstrate the example of while loop public class WhileLoopExample { public static void main(String[] args) { // Printing single message 5 times using while loop int i = 1; while (i<= 5) { System.out.println("javabytechie.com"); i++; } } }

Output

javabytechie.com
javabytechie.com
javabytechie.com
javabytechie.com
javabytechie.com

Java Nested while Loop:

Java also allows to write one while loop inside another while loop, it is knowns as Nested while loop or Inner while loop in Java.

Syntax of Nested while loop in Java

// Outer while loop while(condition checking) { // Inner while loop while (condition checking { // Code } }

Now, let's understand Nested while loop through the given example.

Example 2 : Java Nested while Loop

public class NestedWhileLoopExample { public static void main(String[] args) { int i = 1; // Outer while loop while (i <= 3) { System.out.println("Outer while loop"); int j = 1; // Inner while loop while (j <= 4) { System.out.println("Inner while loop"); j++; } i++; } } }

Output

Outer while loop
Inner while loop
Inner while loop
Inner while loop
Inner while loop
Outer while loop
Inner while loop
Inner while loop
Inner while loop
Inner while loop
Outer while loop
Inner while loop
Inner while loop
Inner while loop
Inner while loop

Infinite while Loop in Java

A loop that does not terminate that loop is known as an Infinite loop in Java.

Example 3 : Infinite while Loop in Java

public class InfiniteWhileLoopExample { public static void main(String args[]) { while(true) { System.out.println("It's an Infinite Loop"); } } }

Output

It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
It's an Infinite Loop
...
...
...

Continue and Break Statements inside while Loop

We can use continue and break statements inside while loop according to our requirement.

In Java, the continue statement is mainly used inside the loops such as for loop, while loop, do-while loop, etc. The purpose of the continue statement is to continue the current running flow of the Java program and skip the rest of the code at the specified condition.

A break statement is used to terminate the current processing of the loop, after the termination control returns from the loop immediately to the next statement after the loop.

Let's understand the below Java program where we are iterating a loop from 1 to 30 but printing the even value from 11-20.

Example 4 : Continue and Break Statements inside while Loop

public class ContinueAndBreakInWhileLoop { public static void main(String[] args) { int i = 1; while(i <= 30) { // Continue statement if(i < 11) { i++; continue; } // Printing even number if(i % 2 == 0) System.out.println("Even Number: " + i); // Break Statement if(i > 20) break; i++; } } }

Output

Even Number: 12
Even Number: 14
Even Number: 16
Even Number: 18
Even Number: 20