Java Programming Lesson 5 | Loops powerful features in Java

LESSON-5: LOOP 

🔥 Let's jump into Lesson-5: Loops — one of the most powerful features in Java.

📘 Lesson 5 — Loops (for, while, do-while)

Loops help us repeat code multiple times without rewriting it.

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✅ 1️⃣ for Loop

We know how many times repetition is needed.

Structure:

for(initialization; condition; increment/decrement){
    // code
}

Example:

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

✅ Output:

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

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✅ 2️⃣ while Loop

We don't always know the number of repetition beforehand — loop continues while condition is true.

Structure:

while(condition){
    // code
}

Example:

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

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✅ 3️⃣ do-while Loop

Executes at least once, even if condition is false.

Structure:

do{
    // code
} while(condition);

Example:

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

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✅ Extra: break & continue

Keyword	Purpose
break	Stops loop immediately
continue	Skips current iteration

Example:

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

Output:

1
2
4
5

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✅ Full Practical Example

public class LoopExample {
    public static void main(String[] args) {

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

        // While Loop
        System.out.println("\nWhile Loop:");
        int j = 1;
        while(j <= 5){
            System.out.println(j);
            j++;
        }

        // Do-While Loop
        System.out.println("\nDo-While Loop:");
        int k = 1;
        do{
            System.out.println(k);
            k++;
        }while(k <= 5);
    }
}

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📝 Exercise for You ✅

Write programs using:

1️⃣ for loop → print numbers 1 to 10
2️⃣ while loop → print even numbers 2 to 20
3️⃣ do-while loop → print numbers decreasing from 5 to 1

Reply with your:

✅ Code
✅ Output

I will check and give feedback ✅🔥

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🎯 Quick Quiz

1️⃣ Which loop must run at least once?
A) for
B) while
C) do-while

2️⃣ Which keyword exits loop immediately?
A) break
B) stop
C) quit

Reply format:
1 → ?, 2 → ?

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✅ Lesson-5 Completed!

Ready for next lessons?

➡ Lesson-6: Arrays (1D & 2D)
or
➡ Lesson-6: Strings (String class & methods)

Which one should we learn first? 😃

▶ NEXT PART - Lesson-5: Arrays (1D & 2D)