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Questions and Answers
What is the purpose of the break statement in a while loop?
What is the purpose of the break statement in a while loop?
What happens when the System.exit() method is called in a Java program?
What happens when the System.exit() method is called in a Java program?
What is a way to break a while loop in Java without using a break statement?
What is a way to break a while loop in Java without using a break statement?
What is the purpose of the return statement in a while loop?
What is the purpose of the return statement in a while loop?
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What is an example of a scenario where a while loop can be used?
What is an example of a scenario where a while loop can be used?
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What is the key characteristic of a Java While Loop?
What is the key characteristic of a Java While Loop?
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When is the condition in a Java While Loop evaluated?
When is the condition in a Java While Loop evaluated?
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What happens if the condition in a While Loop is never met?
What happens if the condition in a While Loop is never met?
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In a Java While Loop, when does the loop terminate?
In a Java While Loop, when does the loop terminate?
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What purpose does the condition serve in a Java While Loop?
What purpose does the condition serve in a Java While Loop?
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Study Notes
Java While Loop
A Java While Loop is a control flow statement that allows code to be executed repeatedly until a certain condition is met. It is often used when the number of iterations isn't fixed, and the loop continues until the condition is no longer true. The while loop syntax in Java is as follows:
while (condition) {
// statements
}
In a while loop, the condition is evaluated first. If the condition is true, the code within the loop is executed. The condition is then checked again, and this process continues until the condition is no longer true, at which point the loop terminates.
While Loop Flowchart
- Control falls into the while loop.
- The flow jumps to the condition.
- The condition is tested.
- If the condition yields true, the flow goes into the body of the loop.
- The statements inside the loop are executed.
- The condition is updated.
- Control flows back to step 2.
- The while loop has ended, and the flow has gone outside.
Examples of While Loop
Simple While Loop
In this example, a while loop is used to print the integer numbers in reverse order starting from 10.
public class WhileLoopExample {
public static void main(String args[]) {
int i = 10;
while (i > 1) {
System.out.println(i);
i--;
}
}
}
Output: 10 9 8 7 6 5 4 3 2 1
Infinite While Loop
An infinite while loop is a loop that never ends. In this example, the condition is never met, causing the loop to execute indefinitely.
public class InfiniteWhileLoopExample {
public static void main(String args[]) {
while (true) {
System.out.println("Infinite loop");
}
}
}
This program will keep printing "Infinite loop" until it is manually stopped.
Breaking a While Loop
There are several ways to break a while loop in Java:
- Using a
breakstatement: This allows you to exit the loop prematurely. - Altering the Boolean condition: If the condition becomes false, the loop will terminate.
- Using a
returnstatement: This causes the program to exit the function, and any while loops within the function will also terminate. - Using the
System.exit()method: This terminates the Java Virtual Machine, stopping all loops and programs.
Exercises
To practice working with while loops, try the following exercises:
- Use a while loop to print the numbers 1 to 10, then 10 to 1.
- Write a program that calculates the sum of numbers entered by the user until they enter a negative number.
- Create a program that counts the number of times a user enters a vowel in a sentence.
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Description
Learn about Java While Loops, a control flow statement used for repeatedly executing code until a specified condition is met. This quiz covers the syntax of while loops, how they work with examples, infinite loops, ways to break a while loop, and includes exercises to practice while loop usage.
