🔁 Part 4: Learn Java Loops — Repeat Tasks Like a Coding Pro

In the real world, we repeat things all the time:

• Wake up → brush teeth → repeat every day
• Watch one more episode → again and again 😅
• Count to 10 → one number at a time

Java lets your code repeat actions automatically using loops — and it’s easier than you think.

🎯 What Is a Loop?

A loop is a way to tell your code:

“Do this thing over and over — until I say stop.”

There are 3 main types:

🧮 1. for Loop: Count Up Like a Pro

for (int i = 1; i <= 5; i++) {
    System.out.println("Step " + i);
}

🧠 What’s Happening?

• int i = 1 → start counting from 1
• i <= 5 → keep going while i is 5 or less
• i++ → increase i by 1 each time

➡ Output:

Step 1
Step 2
Step 3
Step 4
Step 5

🔁 2. while Loop: Repeat Until Something Changes

int x = 3;

while (x > 0) {
    System.out.println("Counting down: " + x);
    x--;
}

➡ Output:

Counting down: 3
Counting down: 2
Counting down: 1

✅ Runs as long as x > 0 is true

🔂 3. do-while Loop: Do It At Least Once

int number = 0;

do {
    System.out.println("This runs once!");
} while (number != 0);

✅ Even if the condition is false, it runs once before checking

🎨 Real Example: Print All Even Numbers from 1 to 10

for (int i = 1; i <= 10; i++) {
    if (i % 2 == 0) {
        System.out.println(i);
    }
}

➡ Output:

2
4
6
8
10

⚠️ Common Mistakes to Avoid

❌ Forgetting to update the counter

while (true) {
    // infinite loop! 😱
}

✅ Always make sure your loop can stop!

🎯 Mini Challenge: Countdown with a Twist

Write a loop that counts from 5 to 1, then prints “Liftoff!”

for (int i = 5; i >= 1; i--) {
    System.out.println(i);
}
System.out.println("Liftoff! 🚀");

🧭 What’s Next? (Part 5 Preview)

In Part 5, you’ll learn how to:

✅ Group data using arrays
✅ Loop through lists of items
✅ Make your programs work with many values

🧪 Java Loop Cheat Sheet

// For loop
for (int i = 0; i < 10; i++) {
    // repeat this 10 times
}

// While loop
while (condition) {
    // repeat while condition is true
}

// Do-while loop
do {
    // run once, then check condition
} while (condition);