Loops In Java

What is a Loop?

A loop is a programming construct that allows you to execute a block of code repeatedly based on a
condition. Loops reduce redundancy and improve code efficiency, especially when the same
operation needs to be performed multiple times.



1. For Loop

Detailed Explanation:

 Purpose: Used when the number of iterations (repetitions) is known beforehand.

 How It Works:

1. The initialization step runs once before the loop starts. It sets up the loop control
variable (e.g., int i = 0).

2. The condition is checked before each iteration:

 If true, the loop body executes.

 If false, the loop stops.

3. The increment/decrement step runs after the loop body to update the loop control
variable.



Syntax:

for (initialization; condition; increment/decrement) {

// Code to execute repeatedly

}



Flowchart:

1. Initialize the loop variable.

2. Check the condition:

o If true, execute the loop body.

o If false, exit the loop.

3. Update the loop variable (increment or decrement).

4. Repeat steps 2 and 3 until the condition becomes false.



Example 1: Print Numbers from 1 to 5

public class ForLoopExample {

, public static void main() {

for (int i = 1; i <= 5; i++) {

System.out.println("Number: " + i);

}

}

}

Output:

Number: 1

Number: 2

Number: 3

Number: 4

Number: 5



Example 2: Calculate the Sum of First 10 Natural Numbers

public class SumExample {

public static void main() {

int sum = 0;

for (int i = 1; i <= 10; i++) {

sum += i; // sum = sum + i

}

System.out.println("Sum of first 10 numbers: " + sum);

}

}

Output:

Sum of first 10 numbers: 55



Practical Uses of For Loop:

 Printing multiplication tables.

 Calculating the factorial of a number.

 Repeating an operation a fixed number of times.