🔄  while loop in Java

When you don’t know how many times a block of code should run, the while loop is your best friend. 💡 It keeps running as long as a condition is true—making it perfect for real-world problems like taking user input, streaming data, or checking server status.

🧐 What is a while loop?

The while loop executes a block of code repeatedly until a condition becomes false.

👉 Syntax:

while(condition) {
    // Code to be executed
}

🔍 How it Works

1️⃣ Condition is checked first (before entering loop).
2️⃣ If true → block of code runs.
3️⃣ If false → loop stops immediately.
4️⃣ After each execution, condition is re-checked.

✅ Example 1: Print Numbers from 1 to 5

int i = 1;
while(i <= 5) {
    System.out.println("Number: " + i);
    i++;
}

Output:

Number: 1
Number: 2
Number: 3
Number: 4
Number: 5

🚀 Why use while loop?

✔️ Best when the number of iterations is unknown.
✔️ Cleaner for input-driven tasks.
✔️ Useful in real-time programs (e.g., waiting for a condition to be met).

⚡ Popular Examples of while loop

1️⃣ Read Input Until User Exits

Scanner sc = new Scanner(System.in);
String input = "";
while(!input.equals("exit")) {
    System.out.print("Enter text (type 'exit' to quit): ");
    input = sc.nextLine();
}

2️⃣ Sum of Digits

int num = 1234, sum = 0;
while(num > 0) {
    sum += num % 10;
    num /= 10;
}
System.out.println("Sum of digits = " + sum);

Output:

Sum of digits = 10

3️⃣ Infinite Loop (⚠️ Be Careful!)

while(true) {
    System.out.println("This will run forever!");
}

💡 Pro Tips

✅ Always make sure the condition will eventually be false → otherwise, infinite loop!
✅ Use break to exit loop early when needed.
✅ Use continue to skip certain iterations.

✨ Difference between for and while

✅ In short:
The while loop is perfect when you need a program to keep running until something happens. Mastering it helps you build interactive, real-world applications in Java. 🚀