Java For Loop

Repeating code execution with controlled iterations

🔄 What is a For Loop?

A for loop in Java repeats a block of code a specific number of times. It's perfect when you know exactly how many times you want to execute code, making repetitive tasks simple and efficient. 


// Simple for loop example
for (int i = 1; i <= 5; i++) {
    System.out.println("Count: " + i);
}

Output: 

Count: 1
Count: 2
Count: 3
Count: 4
Count: 5

For Loop Structure

🎯

Initialization

Set starting value for counter 

int i = 0
✅

Condition

Check if loop should continue 

i < 10
⬆️

Update

Change counter after each iteration 

i++
📦

Body

Code to execute each time 

System.out.println(i);

🔹 Basic For Loop Syntax

The for loop has three parts separated by semicolons: 

for (initialization; condition; update) {
    // Code to execute
}

// Example: Print numbers 1 to 3
for (int i = 1; i <= 3; i++) {
    System.out.println("Number: " + i);
}

Output: 

Number: 1
Number: 2
Number: 3

🔹 Counting Backwards

You can also count backwards by decreasing the counter: 

// Countdown from 5 to 1
for (int i = 5; i >= 1; i--) {
    System.out.println("Countdown: " + i);
}
System.out.println("Blast off!");

Output: 

Countdown: 5
Countdown: 4
Countdown: 3
Countdown: 2
Countdown: 1
Blast off!

🔹 Different Step Sizes

You can increment by any number, not just 1: 

// Count by 2s
for (int i = 0; i <= 10; i += 2) {
    System.out.println("Even number: " + i);
}

// Count by 5s
for (int i = 5; i <= 25; i += 5) {
    System.out.println("Multiple of 5: " + i);
}

Output: 

Even number: 0
Even number: 2
Even number: 4
Even number: 6
Even number: 8
Even number: 10
Multiple of 5: 5
Multiple of 5: 10
Multiple of 5: 15
Multiple of 5: 20
Multiple of 5: 25

🔹 Practical Examples

Here are some useful for loop examples:

🔸 Sum of Numbers 

int sum = 0;
for (int i = 1; i <= 5; i++) {
    sum += i;
    System.out.println("Adding " + i + ", sum is now: " + sum);
}
System.out.println("Final sum: " + sum);

Output: 

Adding 1, sum is now: 1
Adding 2, sum is now: 3
Adding 3, sum is now: 6
Adding 4, sum is now: 10
Adding 5, sum is now: 15
Final sum: 15

🔸 Multiplication Table 

int number = 3;
System.out.println("Multiplication table for " + number + ":");
for (int i = 1; i <= 5; i++) {
    int result = number * i;
    System.out.println(number + " x " + i + " = " + result);
}

Output: 

Multiplication table for 3:
3 x 1 = 3
3 x 2 = 6
3 x 3 = 9
3 x 4 = 12
3 x 5 = 15

🧠 Test Your Knowledge

How many times will this loop run?
for (int i = 0; i < 5; i++)