Java Loops Explained for Beginners | While and For Loop Tutorial

Learn Java loops step by step. Understand while loops, for loops, loop rules, syntax, and examples with beginner-friendly explanations and clear code samples.

🔁 Java Loops

Loops are one of the most powerful concepts in programming. They allow a computer to repeat instructions many times without rewriting code.

Think of loops like telling a student:

“Write your name 10 times.”

Instead of repeating the instruction 10 times, you give one instruction + a rule.

🎯 Why Loops Are Important

Without loops:

• Programs would be very long.
• Repetitive tasks would require duplicate code.
• Maintenance would be difficult.

With loops:

• Code becomes shorter.
• Tasks become automated.
• Programs become efficient.

📌 The 3 Essential Parts of Every Loop

Every loop must have these three parts:

⚠ If update is missing → Infinite loop

🔹 WHILE Loop (Condition-Based Loop)

👉 Use a while loop when you don’t know how many times the loop should run.

Syntax

while(condition){
    // code
}

Example 1 — Print Numbers 1–5

int i = 1;

while(i <= 5){
    System.out.println(i);
    i++;
}

Output

1
2
3
4
5

Example 2 — Password Attempts

int attempts = 1;

while(attempts <= 3){
    System.out.println("Try password");
    attempts++;
}

Real-life logic:

Keep asking until attempts reach limit.

Example 3 — Infinite Loop (Common Mistake)

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

❌ Problem: No i++ → condition never changes.

🔹 FOR Loop (Counting Loop)

👉 Use a for loop when you know exactly how many times you want to repeat something.

Syntax

for(initialization; condition; update){
    // code
}

Example 1 — Print 1–5

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

Example 2 — Print Even Numbers

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

Example 3 — Countdown Timer

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

🔄 WHILE vs FOR (When to Use Which?)

👉 Rule of thumb for beginners:

If counting → use for If waiting for condition → use while

🧠 Practice Tasks

🟢 Easy Tasks

Task 1 — While Loop Print numbers from 10 to 1.

Task 2 — For Loop Print your name 5 times.

Task 3 — For Loop Print all odd numbers from 1–15.

🟡 Medium Tasks

Task 4 — While Loop Calculate sum of numbers 1–10.

Expected Output:

Sum = 55

Task 5 — For Loop Print multiplication table of 7.

Task 6 — While Loop Print numbers divisible by 3 between 1 and 20.

🔴 Challenging Tasks

Task 7 — Pattern Printing

*
**
***
****
*****

Task 8 — Reverse Counting Print numbers from 50 to 0 with step 5.

Task 9 — Guessing Game Logic Keep asking user for number until they enter 7.

(Hint: use while loop)

📘 Related Topics

• Type Casting
• Conditional Statements