Java while loop

🎢 The "While" Loop Rollercoaster in Java 🎢

Welcome to the thrilling world of Java's while loop! Buckle up, because once you start, there's no stopping until the condition says so! 🎡🎠

🎭 What is a while Loop?

A while loop is like that friend who won’t leave your house until you say the magic words: "Loop terminated!" It keeps executing a block of statements as long as the given condition remains true. The moment the condition flips to false, the loop waves goodbye and exits. ✌️

🏆 Best Practice

If you don't know beforehand how many times a loop should run, use a while loop. It's like a bottomless buffet – you keep eating (iterating) until you're full (condition is false). 😋

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🏗️ Syntax

while (condition-expression) {
     // Statement(s) to execute repeatedly
}

🎯 Key Rules

• The condition-expression must be a boolean (true or false).
• If it's true, the loop keeps running.
• If it's false, the loop taps out. 🙅‍♂️
• Be careful! If the condition never becomes false, congrats! You've created an infinite loop! (More on that disaster later. 😅)

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🎬 How the while Loop Works

1. Check the condition.
2. If true, execute the loop body.
3. Rinse and repeat until the condition turns false.
4. Exit the loop and continue with the rest of the code.

Think of it like a treadmill: you keep running as long as you want (or until you pass out). 🏃‍♂️💨

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🏁 Examples

1️⃣ Print Numbers from 1 to 5

Let’s warm up with a simple example. We’ll use a while loop to print numbers from 1 to 5.

int counter = 1;

while (counter <= 5) {
    System.out.println(counter);
    counter++; // Increment the counter, or we'll be stuck forever!
}

🎉 Output:

1
2
3
4
5

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2️⃣ Iterating Through a List

Got a list of things? No problem! Let's loop through them using an Iterator.

List<String> list = List.of("A", "B", "C");
Iterator<String> iterator = list.iterator();

while (iterator.hasNext()) {
    System.out.println(iterator.next());
}

🎉 Output:

A
B
C

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3️⃣ Looping Through an Array

Arrays are like sushi platters 🍣 – you can go through each piece one by one.

Integer[] array = {1, 2, 3, 4, 5};
int index = 0;

while (index < array.length) {
    System.out.println(array[index]);
    index++;
}

🎉 Output:

1
2
3
4
5

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⚠️ The Dreaded Infinite Loop 😱

Oops! If you forget to update the condition inside the loop, you might end up in an endless loop, like a song stuck on repeat. 🔁

Integer[] array = {1, 2, 3, 4, 5};
int index = 0;

while (index < array.length)  // Uh-oh! Forgot to increment `index`
{
    System.out.println(array[index]);
}

🚨 What happens? The program keeps printing the same value forever until your computer melts or you manually stop it. 🔥

💡 Fix: Increment the index inside the loop to ensure termination.

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🤔 while vs. for Loop – The Showdown! ⚔️

Feature	while Loop	for Loop
Condition	Mandatory	Mandatory
Initialization	Outside the loop	Inside the loop
Increment/Update	Inside the loop body	In loop header

🎭 for Loop Syntax

for (initialization; condition-expression; update) {
    // Statements
}

🔄 Equivalent while Loop

initialization;
while (condition-expression) {
    // Statements
    update;
}

👉 Moral of the story? If you need a controlled number of iterations, go with for. If the loop needs to run indefinitely until some condition is met, while is your go-to. ✅

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🛑 Using break in a while Loop

Sometimes, you need an emergency exit! The break keyword can help you stop the loop immediately.

int i = 1;

while (true) {  // Whoa! An infinite loop!
    if (i <= 5) {
        System.out.println(i);
        i++;
    } else {
        break;  // Escape hatch! 🚀
    }
}

🎉 Output:

1
2
3
4
5

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🎉 Wrapping Up

Java's while loop is a powerful tool that keeps your code lean and efficient. Whether you're looping through a collection, waiting for user input, or just having fun with infinite loops (not recommended! 😆), mastering while loops will make you a Java champion! 🏆

Happy Coding! 🚀💻