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Ace the AP Computer Science Exam for High Schoolers

while Loops

Explore how while loops function in Java to repeat code execution based on a condition. Understand loop syntax, execution flow, infinite loops, and the impact of return statements within loops to control program behavior.

We'll cover the following...

Iteration changes the flow of control by repeating a set of statements, zero or more times until a condition is met.

Introduction

In loops, the boolean expression is evaluated before each iteration, including the first iteration. When the expression evaluates to true, the loop body is executed. This continues until the expression evaluates to false, after which the iteration ceases.

Java while loop

The while loop runs a set of instructions as long as a specified condition is true.

Here is it its syntax:

while (condition)
{
    statement(s)     // statements to be executed
}

Example

For example, we want to print all numbers up to 55 on the screen. Run the program below to see how it’s done.

Java
class whileLoop 
{
    public static void main(String args[]) 
    {
        int x = 0;
        // While loop
        while (x <= 5)              // Condition
        {           
            System.out.println(x);  // Printing x if <= 5
            x ++;                     // Incrementing x in every iteration
        }
        System.out.println ("Hi");
    }
}

At line 5, we declare an x variable (type int), and initialize it with 00 ...