Java Day 5: Loops

Goal of this Day

Today you will learn:

• How to use for loops
• How to use while loops
• How to use do-while loops
• How to control loops using break and continue

By the end, you will be able to repeat tasks automatically using loops.

Step 1: for Loop

The for loop is used when you know how many times to repeat something.

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

Explanation:

• int i = 1 → start value
• i <= 5 → condition
• i++ → increment

Step 2: while Loop

The while loop runs as long as a condition is true.

int i = 1;

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

Step 3: do-while Loop

The do-while loop always runs at least once.

int i = 1;

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

Step 4: break and continue

break

Stops the loop completely.

for(int i = 1; i <= 10; i++) {
    if(i == 5) {
        break;
    }
    System.out.println(i);
}

continue

Skips the current iteration.

for(int i = 1; i <= 5; i++) {
    if(i == 3) {
        continue;
    }
    System.out.println(i);
}

Practice

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

Exercise

Print all even numbers from 1 to 50 using a loop.

Steps:

• Use a loop from 1 to 50
• Check if the number is even using %
• Print only even numbers

Example:

public class EvenNumbers {
    public static void main(String[] args) {
        for(int i = 1; i <= 50; i++) {
            if(i % 2 == 0) {
                System.out.println(i);
            }
        }
    }
}