DEV Community: bala d kaveri

🚀 Day 34 of My Automation Journey – Interfaces (Real Programs)

bala d kaveri — Tue, 21 Apr 2026 14:17:54 +0000

Today’s focus was on one of the core OOP concepts – Interfaces 🔥

Instead of only theory, I practiced real-world scenarios using interfaces and understood how they help in scalability, flexibility, and team development.

🔹 What is an Interface?

👉 An interface is a blueprint of a class

✔ Contains abstract methods
✔ Provides 100% abstraction (conceptually)
✔ Used to achieve loose coupling

🔹 Why Interface?

👉 When multiple classes have:
✔ Same behavior
✔ Different implementations

💡 Interface helps define a common contract

🔹 Q1: How does Interface help in Payment Systems?

🧠 Scenario:

Online shopping app supports:

UPI
Credit Card
PayPal

👉 All do payment, but differently

✅ Program:

package interfacedemo;

public class PaymentApp {

    interface Payment {
        void pay(int amount);
    }

    static class UpiPayment implements Payment {
        public void pay(int amount) {
            System.out.println("UPI Payment: " + amount);
        }
    }

    static class CreditCardPayment implements Payment {
        public void pay(int amount) {
            System.out.println("Card Payment: " + amount);
        }
    }

    static class PaypalPayment implements Payment {
        public void pay(int amount) {
            System.out.println("PayPal Payment: " + amount);
        }
    }

    public static void main(String[] args) {

        Payment p = new UpiPayment();
        p.pay(500);

        Payment p1 = new CreditCardPayment();
        p1.pay(1000);

        Payment p2 = new PaypalPayment();
        p2.pay(1500);
    }
}

✅ Output:

UPI Payment: 500
Card Payment: 1000
PayPal Payment: 1500

💡 Explanation:

👉 Interface Payment defines common method pay()
👉 Different classes implement it differently
👉 Easy to add new payment types in future

🔹 Q2: How Interface Works in Vehicles?

🧠 Scenario:

Car starts
Bike starts 👉 Same action, different behavior

✅ Program:

package interfacedemo;

public class VehicleApp {
    interface Vehicle {
        void start();
    }

    static class Car implements Vehicle {
        public void start() {
            System.out.println("Car starts with key ignition or push button");
        }
    }

    static class Bike implements Vehicle {
        public void start() {
            System.out.println("Bike starts with kick or self start");
        }
    }

    public static void main(String[] args) {

        Vehicle v = new Car();
        v.start();

        Vehicle v1 = new Bike();
        v1.start();
    }
}

✅ Output:

Car starts with key ignition or push button
Bike starts with kick or self start

💡 Explanation:

👉 start() is common
👉 Implementation differs per vehicle

🔹 Q3: How Interface Helps in Notification System?

🧠 Scenario:

System sends:

Email
SMS
Push Notification

👉 Future expansion needed

✅ Program:

package interfacedemo;

public class NotificationApp {

    interface Notification {
        void send(String message);
    }

    static class EmailNotification implements Notification {
        public void send(String message) {
            System.out.println("Email sent: " + message);
        }
    }

    static class SMSNotification implements Notification {
        public void send(String message) {
            System.out.println("SMS sent: " + message);
        }
    }

    static class PushNotification implements Notification {
        public void send(String message) {
            System.out.println("Push notification sent: " + message);
        }
    }

    public static void main(String[] args) {

        Notification n = new EmailNotification();
        n.send("Order placed successfully");

        Notification n1 = new SMSNotification();
        n1.send("OTP: 1234");

        Notification n2 = new PushNotification();
        n2.send("New offer available!");
    }
}

✅ Output:

Email sent: Order placed successfully
SMS sent: OTP: 1234
Push notification sent: New offer available!

💡 Explanation:

👉 Easy to extend → WhatsApp / Slack later
👉 No need to change existing code

🔹 Q4: How Interface Helps in Team Development?

🧠 Scenario:

Multiple developers working on modules:

Login
Payment
Reports

👉 Need common structure

✅ Program:

package interfacedemo;

public class TeamProject {

    interface Module {
        void execute();
    }

    static class LoginModule implements Module {
        public void execute() {
            System.out.println("Login Module Executed");
        }
    }

    static class PaymentModule implements Module {
        public void execute() {
            System.out.println("Payment Module Executed");
        }
    }

    static class ReportModule implements Module {
        public void execute() {
            System.out.println("Report Module Executed");
        }
    }

    public static void main(String[] args) {

        Module m = new LoginModule();
        m.execute();

        Module m1 = new PaymentModule();
        m1.execute();

        Module m2 = new ReportModule();
        m2.execute();
    }
}

✅ Output:

Login Module Executed
Payment Module Executed
Report Module Executed

💡 Explanation:

👉 Interface acts as contract
👉 All developers follow same method structure
👉 Ensures consistency

🔥 Key Advantages of Interface

✔ Abstraction
✔ Loose coupling
✔ Scalability
✔ Code reusability
✔ Easy maintenance

🔚 Final Takeaway

👉 Interface is not just theory — it is used everywhere in real projects

From:

Payment systems 💳
Notifications 📩
Vehicles 🚗
Team modules 👨‍💻

👉 It helps in building clean and scalable applications 🚀

💡 Golden Insight

👉 "Interface defines WHAT to do, implementation defines HOW to do"

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while ensuring the concepts remain aligned with my trainer’s explanations.

🚀 Day 32 of My Automation Journey – Exception Handling

bala d kaveri — Fri, 17 Apr 2026 09:50:27 +0000

Today’s learning was all about Exception Handling 🔥

👉 Handling runtime errors
👉 Writing safe programs
👉 Understanding different exception types

This is a must-know concept for writing real-world applications 🚀

🔹 PART A – What is Exception Handling?

👉 An exception is an error that occurs during program execution

💡 Instead of crashing the program, we can handle it gracefully

🔹 Why Exception Handling?

Without exception handling:
❌ Program stops immediately

With exception handling:
✔ Program continues execution
✔ Errors are handled properly

📘 Exception Handling – Quick Revision Notes (Day 32)

While learning Exception Handling, I created these quick revision notes to clearly understand the concepts and hierarchy.

🔹 What is Exception Handling?

Exception handling is a mechanism in Java to handle runtime exceptions and maintain the normal flow of the application.

👉 Without handling → program crashes
👉 With handling → program continues smoothly

🔹 What is an Exception?

An exception is an unexpected event that:

✔ Occurs during runtime
✔ Disrupts normal program execution

🔹 Exception Hierarchy (Very Important 🔥)

Throwable
   |
   |------ Error
   |
   |------ Exception
             |
             |------ Checked Exception
             |
             |------ Unchecked Exception (RuntimeException)

👉 Throwable is the parent class of all errors and exceptions

🔹 Errors

Errors represent serious problems in the application

🔸 Key Points:

❌ Cannot be handled using code
❌ Mostly system-level failures

🔸 Examples:

OutOfMemoryError
StackOverflowError

💡 These are not meant to be handled in normal programs

🔹 Exceptions

Exceptions are manageable problems
👉 Can be handled using try-catch

🔹 Checked Exceptions (Compile-Time)

👉 Also known as compile-time exceptions

🔸 Key Points:

✔ Detected by compiler (JDK)
✔ Program will not execute until fixed
✔ Must be handled or declared

🔸 Examples:

IOException
FileNotFoundException
SQLException
ClassNotFoundException

🔸 Common Causes:

Missing semicolon
Wrong datatype assignment
File handling issues

🔹 Unchecked Exceptions (Runtime)

👉 Also known as runtime exceptions

🔸 Key Points:

✔ Occur during execution
✔ Not checked by compiler
✔ Handling is optional

🔸 Examples:

NullPointerException
ArithmeticException
ArrayIndexOutOfBoundsException

🔥 Checked vs Unchecked

Feature	Checked Exception	Unchecked Exception
Detected	Compile time	Runtime
Handling	Mandatory	Optional
Example	IOException	NullPointerException

🔹 Key Takeaways

✔ Exception = runtime issue
✔ Error = system-level failure
✔ Checked → compile-time
✔ Unchecked → runtime
✔ Throwable = root class

💡 Final Insight

👉 Understanding exceptions is not just about handling errors — it’s about writing stable and reliable programs 🚀

🔥 My Learning

Today I understood:

Difference between error & exception
Compile-time vs runtime issues
Importance of exception hierarchy

🔹 PART B – Types of Exceptions

🔥 1. Null Pointer Exception

✅ Program:

public class NullPointerDemo {
    public static void main(String[] args) {
        String name = null;
        System.out.println(name.length());
    }
}

❌ Output:

Exception in thread "main" java.lang.NullPointerException

🧠 Explanation:

👉 Trying to access method on null object

🔥 2. Arithmetic Exception

✅ Program:

public class ArithmeticDemo {
    public static void main(String[] args) {
        int a = 10;
        int b = 0;
        System.out.println(a / b);
    }
}

❌ Output:

Exception in thread "main" java.lang.ArithmeticException: / by zero

🧠 Explanation:

👉 Division by zero is not allowed

🔥 3. Array Index Out Of Bounds

✅ Program:

public class ArrayIndexDemo {
    public static void main(String[] args) {
        int[] arr = {10, 20, 30};
        System.out.println(arr[5]);
    }
}

❌ Output:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException

🧠 Explanation:

👉 Accessing index outside array size

🔥 4. Negative Array Size Exception

✅ Program:

public class NegativeArrayDemo {
    public static void main(String[] args) {
        int[] arr = new int[-5];
    }
}

❌ Output:

Exception in thread "main" java.lang.NegativeArraySizeException

🧠 Explanation:

👉 Array size cannot be negative

🔹 PART C – Handling Exceptions Using try-catch

✅ Program – Basic Handling

public class TryCatchDemo {
    public static void main(String[] args) {
        try {
            int a = 10;
            int b = 0;
            System.out.println(a / b);
        } catch (ArithmeticException e) {
            System.out.println("Handled Arithmetic Exception");
        }
        System.out.println("Program continues...");
    }
}

✅ Output:

Handled Arithmetic Exception
Program continues...

🧠 Explanation:

👉 Exception is caught and handled
👉 Program continues execution

🔹 PART D – Multiple Catch Blocks

✅ Program:

public class MultipleCatchDemo {
    public static void main(String[] args) {
        try {
            int[] arr = new int[3];
            System.out.println(arr[5]);
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Array Index Exception handled");
        } catch (Exception e) {
            System.out.println("General Exception handled");
        }
    }
}

✅ Output:

Array Index Exception handled

🧠 Explanation:

👉 Specific exception handled first
👉 General exception acts as backup

🔹 PART E – One try, Multiple Catch

public class MultiErrorDemo {
    public static void main(String[] args) {
        try {
            String s = null;
            System.out.println(s.length());
        } catch (NullPointerException e) {
            System.out.println("Null Pointer handled");
        } catch (Exception e) {
            System.out.println("General Exception handled");
        }
    }
}

Output:

Null Pointer handled

🔹 PART F – try After catch (Important Concept 🔥)

👉 Yes, we can write another try after catch

✅ Program:

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

        try {
            int a = 10 / 0;
        } catch (ArithmeticException e) {
            System.out.println("First exception handled");
        }

        try {
            String s = null;
            System.out.println(s.length());
        } catch (NullPointerException e) {
            System.out.println("Second exception handled");
        }
    }
}

✅ Output:

First exception handled
Second exception handled

🧠 Explanation:

👉 After one try-catch, we can write another
👉 Each block handles its own exception

🔹 PART G – Important Rules ⚠️

✔ Only one exception occurs at a time
✔ Catch specific exception first
✔ Exception class should be last
✔ Program continues after handling

🔚 FINAL TAKEAWAYS

✔ Exception = runtime error
✔ try-catch prevents program crash
✔ Multiple exceptions can be handled
✔ Specific catch is important
✔ Clean error handling = better code

💡 GOLDEN INSIGHT

👉 Exception handling makes your program strong, safe, and production-ready 🚀

Stay tuned 🚀

🚀 Day 31 of My Automation Journey – IntelliJ Setup, GitHub Copilot & Developer Tools

bala d kaveri — Thu, 16 Apr 2026 17:47:10 +0000

Today was a practical + tools-focused day 🔥

Instead of only coding, I explored the developer ecosystem — the tools that actually make coding faster, smarter, and industry-ready.

🔹 PART A – Installing IntelliJ IDEA

🧰 What is IntelliJ IDEA?

👉 IntelliJ IDEA is a powerful IDE for Java development.

✔ Smart code suggestions
✔ Built-in debugging
✔ Easy project management

🔹 Installation Steps

Download from official website
Install with default settings
Open → Create New Project
Choose Java + Maven (recommended)

🔹 My First Experience

Clean UI
Smart suggestions
Easy navigation
Faster compared to traditional IDEs

💡 Compared with Eclipse IDE, IntelliJ felt more intuitive

🔹 PART B – Writing Code with AI (Game Changer 🔥)

Today I explored AI-assisted coding tools 👇

🤖 1. GitHub Copilot

👉 GitHub Copilot helps to:
✔ Auto-complete code
✔ Suggest logic
✔ Reduce typing effort

Example:

// Check prime number

👉 Copilot suggests full logic automatically 😲

🤖 2. Claude

👉 Claude helps in:
✔ Explaining code
✔ Debugging errors
✔ Improving logic

🤖 3. Cursor AI

👉 Cursor is a next-gen IDE:

✔ Chat with code
✔ Modify entire files
✔ Smart refactoring

💡 My Learning

👉 AI tools don’t replace developers
👉 They accelerate learning & productivity

🔹 PART C – My Real Experience

Today I tried:

✔ Writing Java code
✔ Asking AI to fix errors
✔ Understanding IDE hints

🔍 Important Observation

👉 Grey lines & green highlights in IntelliJ are:

Suggestions
Hints
Not errors

💡 IDE helps improve code quality automatically

🔹 PART D – Important Development Tools

These tools are must-know for automation & real projects 🚀

🔧 1. Jenkins

👉 Jenkins

✔ Used for CI/CD
✔ Automates build & deployment
✔ Runs tests automatically

🔧 2. Git & GitHub

👉 Git
👉 GitHub

✔ Version control
✔ Track code changes
✔ Collaboration

🔧 3. Maven

👉 Apache Maven

✔ Dependency management
✔ Build automation
✔ Project structure

🔧 4. IntelliJ IDEA vs Eclipse

Feature	IntelliJ	Eclipse
UI	Modern	Basic
Speed	Fast	Moderate
AI Support	Strong	Limited

🔹 PART E – Why These Tools Matter

👉 In real projects:

✔ Code is written using IDE
✔ Managed using Git
✔ Built using Maven
✔ Deployed using Jenkins
✔ Enhanced using AI tools

🔥 FINAL TAKEAWAYS

✔ IntelliJ improves productivity
✔ GitHub Copilot speeds up coding
✔ Claude helps understand logic
✔ Maven manages dependencies
✔ Jenkins automates workflow

💡 Golden Insight

👉 Tools don’t make you a developer — but knowing them makes you industry-ready 🚀

Stay tuned 🚀

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 30 of My Automation Journey – Java Strings (Package, Memory, Limitations & Real-Time Usage) - part 2

bala d kaveri — Thu, 09 Apr 2026 13:48:38 +0000

When learning Java, most people understand what a String is, but very few understand:

👉 Which package it belongs to
👉 Why it has limitations
👉 How Java overcomes those limitations
👉 Memory behaviour of Strings
👉 Real-time usage in projects

Let’s break everything down in a simple and practical way 👇

📦 1. Which Package Does String Belong To?

👉 The String class belongs to:

java.lang.String

Important Points:

java.lang package is imported by default
So you don’t need to write:

import java.lang.String;

👉 That’s why we directly use:

String name = "Bala";

🧱 2. What Type of Class is String?

👉 String is a:

Final class ❌ (cannot be inherited)
Immutable class 🔒 (cannot be changed)

public final class String

Why final?

👉 For security and consistency

⚠️ 3. Demerits of String in Java

Even though String is powerful, it has some drawbacks:

❌ 1. Immutable (Cannot Modify)

String s = "Hello";
s = s + " World";

👉 Creates new object every time

❌ 2. Memory Consumption

Too many modifications → too many objects
Increases memory usage

❌ 3. Performance Issue

String operations are slower when frequently modified

💡 4. How Java Overcomes String Limitations?

Java provides better alternatives 👇

🔹 1. StringBuilder (Recommended)

StringBuilder sb = new StringBuilder("Hello");
sb.append(" World");

✅ Advantages:

Mutable (can change)
Faster
Less memory usage

🔹 2. StringBuffer

StringBuffer sb = new StringBuffer("Hello");

✅ Advantages:

Thread-safe
Mutable

❗ Slightly slower than StringBuilder

🧠 Simple Understanding

Feature	String	StringBuilder	StringBuffer
Mutable	❌	✅	✅
Thread Safe	✅	❌	✅
Performance	Slow	Fast	Medium

🧠 5. Memory Behavior of String

📌 Where are Strings stored?

👉 In Heap Memory
👉 Inside a special area called:

🔹 String Constant Pool (SCP)

Example:

String s1 = "Java";
String s2 = "Java";

👉 Both refer to same memory (SCP) ✅

Using new keyword:

String s3 = new String("Java");

👉 Creates new object ❌

📏 6. What is the Memory Limit of String?

👉 There is no fixed limit like:

String max = 1000 characters ❌

Real Answer:

👉 Depends on:

JVM Heap Size
System Memory

Theoretical Limit:

👉 Maximum size ≈ 2^31 - 1 characters (Integer.MAX_VALUE)

Practical Limit:

👉 Much lower (based on RAM)

⚠️ 7. Is High Memory Usage a Disadvantage?

👉 YES — if misused

Example:

String s = "";
for(int i = 0; i < 10000; i++) {
    s = s + i;
}

👉 Creates 10000 objects ❌

Better Approach:

StringBuilder sb = new StringBuilder();
for(int i = 0; i < 10000; i++) {
    sb.append(i);
}

👉 Only 1 object ✅

🏢 8. Real-Time Usage of String

Strings are used everywhere in real-world projects 👇

🌐 1. Web Automation (Selenium)

driver.get("https://google.com");
driver.findElement(By.id("username")).sendKeys("admin");

👉 URLs, locators, input → all Strings

📂 2. File Handling

String path = "C:/Users/file.txt";

🗄️ 3. Database Queries

String query = "SELECT * FROM users";

🔐 4. Password & Security

String password = "admin123";

📧 5. API Testing

String json = "{ \"name\": \"Bala\" }";

🔥 9. When to Use What?

Scenario	Best Choice
Normal usage	String
Frequent modification	StringBuilder
Multi-threaded environment	StringBuffer

🧠 10. Interview Ready Points

👉 String belongs to java.lang
👉 It is final & immutable
👉 Stored in String Constant Pool
👉 Memory depends on JVM
👉 Use StringBuilder for performance

🏁 Final Summary

👉 String is simple but powerful
👉 It has limitations (immutability, memory)
👉 Java solved it using:

StringBuilder
StringBuffer

👉 Mastering String = Strong Java foundation 💯

💬 Final Thought

If you understand how String behaves internally, you can:
✔ Write optimized code
✔ Crack interviews easily
✔ Build efficient automation scripts

Stay tuned 🚀

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 30 of My Automation Journey – Strings in Java - part 1

bala d kaveri — Thu, 09 Apr 2026 13:38:19 +0000

🧵 What is String in Java?

If you are just starting with Java, one of the most important things you’ll learn is String.
Don’t worry — we’ll explain this in a very simple way so that even a 10th-grade student can understand 👍

📌 1. Introduction – What is a String?

👉 A String in Java is simply a sequence of characters.

Example:

String name = "Bala";

Here:

"Bala" is a String
It contains characters: B, a, l, a

🧠 Real-Life Example

Think of a String like:

Your name → "Ravi"
A sentence → "I love Java"
A password → "abc123"

👉 Anything inside double quotes (" ") is a String in Java.

🏗️ 2. How String Came into Java (Origin)

Java was created to be:

Secure 🔐
Simple ✨
Reliable 💪

So, the designers of Java made Strings:

✅ Immutable (Very Important Concept)

👉 Once created, a String cannot be changed

Why?

Security (no one can modify passwords, URLs)
Performance (reuse of same String)
Thread safety (safe in multi-threading)

🧱 3. How String is Stored in Memory

There are two ways Strings are created:

🔹 Method 1: String Literal (Recommended)

String s1 = "Hello";
String s2 = "Hello";

👉 Both will share the same memory

This area is called:
👉 String Constant Pool (SCP)

🔹 Method 2: Using `new` Keyword

String s3 = new String("Hello");

👉 This creates a new object in heap memory
👉 Even if "Hello" already exists

🧠 Simple Understanding

Method	Memory Usage
Literal	Reuses memory ✅
new	Creates new memory ❌

🔐 4. What is Immutability?

String s = "Hello";
s = s + " World";

👉 You might think original String changed ❌
👉 Actually, Java creates a new String

Memory View:

"Hello" → old object
"Hello World" → new object

👉 Old one stays unchanged

💡 Why Immutability is Important?

Security (used in passwords, URLs)
Performance (String pool reuse)
Safe in multi-threading

⚙️ 5. Common String Operations

🔹 Length

s.length();

🔹 Convert to Uppercase

s.toUpperCase();

🔹 Compare Strings

s1.equals(s2);

🔹 Get Character

s.charAt(0);

🔹 Substring

s.substring(0, 3);

⚠️ 6. == vs equals() (Very Important)

String a = "Java";
String b = "Java";

Using `==`

👉 Checks memory location

Using `equals()`

👉 Checks actual value ✅

❌ Example:

String a = new String("Java");
String b = new String("Java");

System.out.println(a == b);       // false ❌
System.out.println(a.equals(b));  // true ✅

🌟 7. Merits (Advantages of String)

✅ 1. Immutable (Safe)

No accidental changes

✅ 2. Memory Efficient

Uses String Pool

✅ 3. Thread Safe

Safe for multiple users

✅ 4. Easy to Use

Many built-in methods

⚠️ 8. Demerits (Disadvantages of String)

❌ 1. Cannot Modify

Every change creates new object

❌ 2. Memory Waste (if overused)

Too many objects → performance issue

❌ 3. Slower for Frequent Changes

Better use:

StringBuilder or StringBuffer

🔁 9. When to Use What?

Situation	Use
Normal text	String
Frequent changes	StringBuilder
Multi-thread	StringBuffer

🔥 10. Interview Tips

👉 Always mention:

String is immutable
Stored in String Constant Pool
Difference between == and .equals()

🏁 Final Summary

👉 String = sequence of characters
👉 Immutable = cannot be changed
👉 Stored in String Pool (memory efficient)
👉 Use .equals() to compare values

💬 Final Thought

If you understand String deeply, you’ve already covered 50% of Java fundamentals 💯

Stay tuned 🚀

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 29 of My Automation Journey – Arrays (Full Guide + Tricky Questions)

bala d kaveri — Mon, 06 Apr 2026 18:59:58 +0000

Today’s learning was one of the most important milestones in my journey 🔥

👉 Arrays (core concept)
👉 JVM internal behaviour
👉 Memory understanding
👉 Tricky interview questions
👉 Deep dive into public static void main

This is where coding becomes real engineering 🚀

🔹 PART A – ARRAYS COMPLETE THEORY

🔹 1. What is an Array?

👉 An array is an object

👉 It is a container that:
✔ Stores multiple values
✔ Same data type
✔ Fixed size

🔹 2. What Happens Internally (JVM 🔥)

int[] arr = {10, 20, 30};

👉 Internally JVM converts:

int[] arr = new int[]{10, 20, 30};

💡 JVM:

Creates object in Heap memory
Stores reference in variable

🔹 3. Proof – Array is an Object

System.out.println(arr.getClass());

Output:

class [I

🔹 4. Array Creation

int[] arr1 = {10, 20, 60, 30};
int[] arr2 = new int[5];

🔹 5. Important Points ⚠️

✔ Fixed size
✔ Index starts from 0
✔ Stored in Heap
✔ Default values assigned

🔹 6. Default Values

Type	Default
int	0
boolean	false
object	null

🔹 7. Initialization & Access

arr[0] = 10;
System.out.println(arr[0]);

🔹 8. Looping Through Array

Normal Loop:

for(int i = 0; i < arr.length; i++) {
    System.out.println(arr[i]);
}

Enhanced Loop:

for(int num : arr) {
    System.out.println(num);
}

🔹 9. Multi-Dimensional Array

int[][] matrix = {
    {1, 2},
    {3, 4}
};

🔹 PART B – PROGRAMS

✅ Program 1 – Default Values

int[] arr = new int[3];
System.out.println(arr[0] + " " + arr[1] + " " + arr[2]);

Output:

0 0 0

❌ Program 2 – Index Error

int[] arr = new int[3];
System.out.println(arr[3]);

Output:

ArrayIndexOutOfBoundsException

❌ Program 3 – Length Modification

int[] arr = {1, 2, 3};
System.out.println(arr.length);
arr.length = 10;

Output:

3
Compilation Error

🔥 Program 4 – Reference Behavior

int[] a = {1, 2, 3};
int[] b = a;
b[0] = 100;
System.out.println(a[0]);

Output:

🔥 Program 5 – Comparing Arrays

int[] a = {1, 2, 3};
int[] b = {1, 2, 3};
System.out.println(a == b);

Output:

false

❌ Program 6 – Null Array

int[] arr = null;
System.out.println(arr.length);

Output:

NullPointerException

❌ Program 7 – Negative Size

int[] arr = new int[-5];

Output:

NegativeArraySizeException

🔹 PART C – PRACTICE PROGRAM

package modul4;

import java.util.Scanner;

public class ArrayPractise {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        System.out.println("Enter array Length: ");
        int count = sc.nextInt();

        byte[] by = new byte[count];
        short[] sh = new short[count];

        System.out.println("Byte ");
        for (int i = 0; i < count; i++) {
            System.out.println(by[i]);
        }

        System.out.println("Short ");
        for (int i = 0; i < count; i++) {
            System.out.println(sh[i]);
        }
    }
}

🔍 Output Insight

👉 Prints 0 because of default values

🔹 PART D – MEMORY & ADVANCED CONCEPTS

Separate Memory

int[] a = new int[3];
int[] b = new int[3];

👉 Stored in different memory

Passing Array

void test(int[] arr) {
    arr[0] = 999;
}

👉 Passed by reference

🔹 PART E – TRICKY QUESTIONS

❓ Q1

int[] arr = new int[3];
System.out.println(arr[0] + " " + arr[1] + " " + arr[2]);

✔ Output: 0 0 0
👉 Default values

❓ Q2

System.out.println(arr[3]);

❌ Output: Exception
👉 Index out of range

❓ Q3

arr.length = 10;

❌ Compilation error
👉 Length is final

❓ Q4

int[] b = a;

✔ Same reference

❓ Q5

System.out.println(a == b);

❌ false
👉 Different objects

❓ Q6

int[] arr = null;
System.out.println(arr.length);

❌ NullPointerException

❓ Q7

new int[-5];

❌ NegativeArraySizeException

🔹 PART F – public static void main (DETAILED 🔥)

public static void main(String[] args)

🔍 Deep Breakdown

🔹 public

👉 JVM must access it

🔹 static

👉 No object required

👉 JVM calls directly:

ClassName.main()

🔹 void

👉 No return value

🔹 main

👉 Entry point

🔹 String[] args

👉 Command-line input

java Test hello

👉 args = ["hello"]

💡 Important Insight

👉 Without main() → program won’t run

🔚 FINAL TAKEAWAYS

✔ Array = Object
✔ JVM handles memory
✔ Default values exist
✔ Reference behavior matters
✔ Exceptions are important
✔ main() is entry point

💡 GOLDEN INSIGHT

👉 Arrays are the foundation of all data structures 🚀

Stay tuned 🚀

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 28 of My Automation Journey – Nested For Loop

bala d kaveri — Thu, 02 Apr 2026 14:19:05 +0000

Today’s learning was super important 👇

👉 Moving from single loops → nested loops
👉 This is where pattern logic begins 🔥

🔹 1. What is a Nested Loop?

👉 A loop inside another loop is called a nested loop

💡 Structure:

for(row) {
    for(column) {
        // logic
    }
}

🧠 How It Works

👉 Outer loop → controls rows
👉 Inner loop → controls columns

🔹 2. Basic Example (Print 1’s)

for(int row = 1; row <= 2; row++) {
    for(int col = 1; col <= 5; col++) {
        System.out.print(1);
    }
    System.out.println();
}

📤 Output:

11111
11111

🔹 3. Print Row Number

for(int row = 1; row <= 2; row++) {
    for(int col = 1; col <= 5; col++) {
        System.out.print(row);
    }
    System.out.println();
}

📤 Output:

11111
22222

🔹 4. Print Column Number

for(int row = 1; row <= 2; row++) {
    for(int col = 1; col <= 5; col++) {
        System.out.print(col);
    }
    System.out.println();
}

📤 Output:

12345
12345

🔹 5. Rectangle Pattern ⭐

for(int row = 1; row <= 3; row++) {
    for(int col = 1; col <= 5; col++) {
        System.out.print("*");
    }
    System.out.println();
}

📤 Output:

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

🔹 6. Reverse Triangle Pattern 🔻

int count = 5;

for(int row = 1; row <= 5; row++) {
    for(int col = 1; col <= count; col++) {
        System.out.print("*");
    }
    System.out.println();
    count--;
}

📤 Output:

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

🔹 7. Triangle Pattern 🔺

int count = 1;

for(int row = 1; row <= 5; row++) {
    for(int col = 1; col <= count; col++) {
        System.out.print("*");
    }
    System.out.println();
    count++;
}

📤 Output:

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

🔍 Key Concept (Very Important 🔥)

👉 Inner loop runs completely for each outer loop iteration

Example:

Row 1 → full columns execute
Row 2 → full columns execute again

⚠️ Common Mistake

👉 Forgetting System.out.println();

System.out.print("*"); // stays in same line
System.out.println();  // moves to next line

🔹 Real Understanding Trick 💡

Think like a table:

Row	Columns Execution
1	1 → 5
2	1 → 5

👉 That’s how patterns are built

🔚 Final Takeaways

✔ Nested loop = loop inside loop
✔ Outer loop → rows
✔ Inner loop → columns
✔ Used for pattern problems
✔ Base for advanced logic

💡 Golden Insight

👉 If you understand nested loops, you unlock pattern programming 🔓

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 27 of My Automation Journey – Introduction to Selenium & Maven Setup

bala d kaveri — Thu, 02 Apr 2026 13:06:27 +0000

Today marks a big milestone in my automation journey 🎯

Till now, I was learning core Java logic
👉 Today, I stepped into real automation using Selenium

This is where things get exciting 🔥

🔹 1. What is Selenium?

👉 Selenium is a tool used for automating web browsers

That means:

Opening a browser 🌐
Navigating websites
Clicking buttons
Filling forms
Validating UI

💡 In simple terms:

👉 If you can do it manually in a browser, Selenium can automate it.

🔹 2. Why Selenium?

✔ Saves time ⏱
✔ Reduces manual effort
✔ Useful for testing & automation
✔ Industry standard tool

🔹 3. Setting Up Selenium using Maven

Instead of downloading jars manually, we use Maven 📦

👉 Maven helps manage:

Dependencies
Versions
Project structure

🔹 4. Understanding `pom.xml` File

This is the heart of a Maven project ❤️

💻 Sample `pom.xml`:

<project xmlns="http://maven.apache.org/POM/4.0.0">

    <modelVersion>4.0.0</modelVersion>

    <groupId>Selenium1</groupId>
    <artifactId>Selenium1</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.seleniumhq.selenium</groupId>
            <artifactId>selenium-java</artifactId>
            <version>4.18.1</version>
        </dependency>

    </dependencies>

</project>

🔍 Explanation (Important 🔥)

🧠 Project Info:

groupId → Project/company name
artifactId → Project name
version → Current version

⚙️ Properties:

<maven.compiler.source>17</maven.compiler.source>

👉 Defines Java version

📦 Dependencies:

<dependency>

👉 This is where we add external libraries

🔹 5. How to Add Dependency from Maven Repository

👉 Go to: mvnrepository.com

Steps:

Search → selenium-java
Select latest version
Copy dependency
Paste inside <dependencies>

💡 Why this is important?

👉 Instead of manual setup, Maven automatically:

Downloads jars
Manages versions
Handles conflicts

🔹 6. Creating Selenium Setup

Once dependency is added ✅

👉 Maven will download everything automatically

Now we are ready to write our first automation program 🚀

🔹 7. First Selenium Program

package first;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;

public class First {

    public static void main(String[] args) {

        ChromeDriver driver = new ChromeDriver();
        driver.get("https://google.com");

    }
}

🔍 Logic Explained:

ChromeDriver → launches Chrome browser
driver.get() → opens website

👉 That’s it! Your first automation script 🎉

⚠️ Important Notes:

✔ ChromeDriver should match browser version
✔ Browser will open automatically
✔ Close using driver.quit()

🔹8. 🌐 Browsers Supported by Selenium

Selenium supports multiple browsers using specific drivers 👇

✅ Browser / Driver Mapping

Browser	Driver
Google Chrome	ChromeDriver
Mozilla Firefox	GeckoDriver
Microsoft Edge	EdgeDriver
Safari	SafariDriver
Internet Explorer	IEDriverServer
Opera	OperaDriver
Chromium	ChromeDriver
Brave	ChromeDriver
Vivaldi	ChromeDriver

💡 Key Insight:

👉 Most modern browsers are Chromium-based

👉 So they work using ChromeDriver

🔹9. 💻 Operating Systems Supported by Selenium

Selenium is cross-platform and works across multiple environments 👇

✅ OS / Support Type

Operating System	Support
Windows	Supported
macOS	Supported
Linux	Supported
Unix	Supported

🔧 Extended Environment Support

Environment	Support
Docker	Supported
Jenkins (CI/CD)	Supported
GitHub Actions	Supported
AWS / Azure / GCP	Supported

💡 Key Insight:

👉 Selenium scripts can run on any OS where browser + driver is available

👉 This enables:
✔ Cross-browser testing

✔ Cross-platform automation

✔ Scalable test execution 🚀

🔹 10. Real-World Use Cases

👉 Login automation
👉 Form submissions
👉 Testing UI flows
👉 Web scraping (basic level)

🔚 Final Takeaways

✔ Selenium = Browser Automation
✔ Maven = Dependency Management
✔ pom.xml = Project configuration
✔ Easy setup using Maven repository
✔ First step into real automation 🚀

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 26 of My Automation Journey – Conditions, Inputs & Do-While Loop

bala d kaveri — Tue, 31 Mar 2026 13:21:31 +0000

Today’s session was a mix of core Java fundamentals + tricky logic + real-world usage 💡
We explored how conditions work, how loops behave without braces, user input handling, and even touched JSON/XML basics.

Let’s break it down step by step 👇

🔹 1. Condition Must Be Boolean (True/False)

In Java, every condition must return either true or false.

❌ Invalid Example

int i = 1;
while(i) {   // ❌ Compilation Error
    System.out.println(i);
}

👉 Why error?

Java does NOT allow non-boolean conditions
Unlike C/C++, numbers are not treated as true/false

✅ Correct Example

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

✔ Condition → i <= 5 → returns boolean
✔ Hence valid

🔹 2. True / False Direct Conditions

You can directly use true or false in conditions.

✅ Example

if(true) {
    System.out.println("Always runs");
}

✔ Output:

Always runs

❌ Example

if(false) {
    System.out.println("Never runs");
}

✔ Output:

(no output)

👉 This is useful for testing or debugging

🔹 3. Removing Curly Braces `{ }`

Java allows skipping { } if only one statement is present.

✅ Example

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

✔ Output:

1 2 3 4 5

⚠️ Tricky Case

for(int i = 1; i <= 5; i++)
    System.out.println(i);
    System.out.println("Done");

✔ Output:

1 2 3 4 5
Done

👉 Only the first statement is inside loop
👉 Second statement runs once after loop

🔹 4. Infinite Loop (By Default True)

If condition is always true → loop never stops 😱

Example

for(;;) {
    System.out.println("Infinite Loop");
}

👉 This is equivalent to:

while(true) {
    System.out.println("Infinite Loop");
}

✔ Used in:

Servers
Continuous monitoring systems

🔹 5. break and continue

🔸 break → stops loop completely

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

✔ Output:

1
2

🔸 continue → skips current iteration

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

✔ Output:

🔹 6. Taking Input from User (Scanner)

To read input in Java, we use Scanner.

Example

import java.util.*;

public class Test {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter your name: ");
        String name = sc.nextLine();

        System.out.println("Hello " + name);
    }
}

⚠️ Important Notes

❌ Java does NOT directly support char input
✔ Workaround:

char ch = sc.next().charAt(0);

✔ For String:

String name = sc.nextLine();

🔹 7. Multiple Inputs Example

Scanner sc = new Scanner(System.in);

System.out.print("Enter Tamil mark: ");
int tamil = sc.nextInt();

System.out.print("Enter English mark: ");
int english = sc.nextInt();

int total = tamil + english;

System.out.println("Total mark: " + total);

✔ Output Example:

Enter Tamil mark: 80
Enter English mark: 90
Total mark: 170

🔹 8. JSON vs XML (Basic Understanding)

🔸 JSON (JavaScript Object Notation)

{
  "username": "Manikandan",
  "password": "1234"
}

✔ Lightweight
✔ Easy to read
✔ Mostly used in APIs

🔸 XML (Extensible Markup Language)

<user>
    <username>Manikandan</username>
    <password>1234</password>
</user>

✔ Structured format
✔ Used in older systems / configs

🔹 9. Do-While Loop

👉 Runs at least once, even if condition is false

Example

int i = 1;

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

✔ Output:

1 2 3 4 5

🔥 Key Difference

Loop Type	Condition Check
while	Before execution
do-while	After execution

🧠 Key Takeaways

✔ Condition must always be boolean
✔ Java does NOT allow non-boolean conditions
✔ Without {}, only one statement is considered
✔ Infinite loops happen when condition is always true
✔ break → exits loop
✔ continue → skips iteration
✔ Scanner is used for user input
✔ JSON is lightweight, XML is structured
✔ do-while runs at least once

🏁 Conclusion

Today was all about understanding how Java actually behaves under the hood 🧠

These small concepts are very important when:

Writing automation scripts
Handling test data
Building logic-driven frameworks

🔥 Step by step, building strong fundamentals in automation!

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 25 of My Automation Journey – Deep Dive into Logic (Part 2)

bala d kaveri — Mon, 30 Mar 2026 12:40:28 +0000

Continuing from earlier, here are the remaining core number programs with full step-by-step explanations to strengthen logic building 👇

🔹 6. Divisors of a Number – Correct Logic

💻 Program:

int user = 15;

for(int i = 1; i <= user; i++) {
    if(user % i == 0)
        System.out.println(i);
}

🧠 Logic Explained:

user % i == 0 means:
👉 “Can i divide user without remainder?”
Loop runs from 1 → 15

🔍 Step-by-Step Trace:

i	15 % i	Result
1	0	✅ Print
2	1	❌
3	0	✅
4	3	❌
5	0	✅
15	0	✅

📤 Output:

1 3 5 15

💡 Key Insight:

👉 Divisors are numbers that perfectly divide the given number

🔹 7. Count of Divisors

💻 Program:

int user = 15;
int count = 0;

for(int i = 1; i <= user; i++) {
    if(user % i == 0)
        count++;
}

System.out.println(count);

🧠 Logic Explained:

Same logic as divisors
Instead of printing → we count

🔍 Example:

Divisors of 15 → 1, 3, 5, 15

👉 Count = 4

📤 Output:

💡 Key Insight:

👉 Reuse logic + add counter → powerful pattern

🔹 8. Count of Digits

💻 Program:

int user = 12345;
int count = 0;

while(user > 0) {
    user = user / 10;
    count++;
}

System.out.println(count);

🧠 Logic Explained:

Each division by 10 removes one digit

🔍 Step-by-Step:

Step	user	count
1	12345 → 1234	1
2	1234 → 123	2
3	123 → 12	3
4	12 → 1	4
5	1 → 0	5

📤 Output:

💡 Key Insight:

👉 Number of times you divide = number of digits

🔹 9. Sum of Digits

💻 Program:

int user = 123;
int sum = 0;

while(user > 0) {
    int digit = user % 10;
    sum = sum + digit;
    user = user / 10;
}

System.out.println(sum);

🧠 Logic Explained:

We do 3 operations:

Extract last digit → % 10
Add to sum
Remove digit → / 10

🔍 Step-by-Step:

Step	digit	sum	user
1	3	3	12
2	2	5	1
3	1	6	0

📤 Output:

💡 Key Insight:

👉 % 10 and / 10 are the backbone of number problems

🔹 10. Palindrome Number

💻 Program:

int user = 121;
int original = user;
int reverse = 0;

while(user > 0) {
    int digit = user % 10;
    reverse = reverse * 10 + digit;
    user = user / 10;
}

if(original == reverse)
    System.out.println("Palindrome");
else
    System.out.println("Not Palindrome");

🧠 Logic Explained:

👉 A palindrome reads the same forward and backward

🔍 Step-by-Step:

Step	digit	reverse	user
1	1	1	12
2	2	12	1
3	1	121	0

📤 Output:

Palindrome

❌ Non-Palindrome Example:

123 → reverse = 321 → Not equal

💡 Key Formula:

reverse = reverse * 10 + digit

🔚 Final Takeaways

✔ Divisors → user % i == 0
✔ Count → reuse + increment
✔ Digits → / 10 removes digits
✔ Sum → % 10 extracts digits
✔ Palindrome → reverse + compare

💡 Golden Rule

👉 Almost ALL number-based problems depend on:

% 10  → Extract last digit
/ 10  → Remove last digit

Master this → you unlock most logic problems 🚀

🔥 Consistency + tracing logic = strong programming foundation!

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 25 of My Automation Journey – Prime Numbers, Reverse Logic & Loops

bala d kaveri — Mon, 30 Mar 2026 12:12:16 +0000

Today, instead of just writing programs, I focused on understanding the “WHY” behind each logic. Let’s break everything down step by step 👇

🔹 1. Divisors Logic – Step-by-Step Understanding

💻 Program:

int user = 15;
int i = 0;

while (i <= user) {
    if (i % user == 0)
        System.out.println(i);
    i++;
}

🧠 Logic Explained:

i % user == 0 means:
👉 “Is i divisible by user?”
Loop runs from 0 → 15

Let’s trace:

i value	i % 15	Condition
0	0	✅ Print
1–14	Not 0	❌ Skip
15	0	✅ Print

📤 Output:

0
15

⚠️ Important Insight:

👉 This program is actually finding multiples of 15 within range, NOT divisors.

✅ Correct Divisor Logic should be:

if (user % i == 0)

🔹 2. Prime Number Logic – Deep Explanation

💻 Program:

int user = 3;
boolean status = true;
int i = 2;

while(i < user) {
    if(user % i == 0) {
        status = false;
        break;
    }
    i++;
}

if (status==true)
    System.out.println("Prime");
else
    System.out.println("Not a prime");

🧠 What is a Prime Number?

A number is prime if:

It has exactly 2 factors → 1 and itself

🔍 Step-by-Step Flow:

Start checking from i = 2
Why?
👉 Because:
- Dividing by 1 is always true
- Dividing by itself is always true So we skip both

🧪 Example: user = 3

i	Condition (3 % i)	Result
2	3 % 2 ≠ 0	Continue

Loop ends → No divisor found → Prime ✅

💡 Why `boolean status`?

Acts like a flag
Initially assume → true (prime)
If any divisor found → false

⚡ Why `break`?

As soon as one divisor is found: 👉 No need to continue checking 👉 Improves performance 🚀

🔹 3. Reverse Number Logic – Deep Breakdown

💻 Program:

int user = 123;
int reverse = 0;

while(user > 0) {
    int digit = user % 10;
    reverse = reverse * 10 + digit;
    user = user / 10;
}

System.out.println(reverse);

🧠 Core Idea:

We:

Extract last digit
Append it to reverse
Remove last digit

🔍 Step-by-Step Execution:

Step	user	digit	reverse calculation	reverse
1	123	3	0*10 + 3	3
2	12	2	3*10 + 2	32
3	1	1	32*10 + 1	321

📤 Output:

💡 Key Formula:

reverse = reverse * 10 + digit

👉 This shifts digits left and adds new digit

🔹 4. While Loop vs For Loop – Conceptual Clarity

🔁 While Loop

int i = 0;
while(i <= 10) {
    System.out.println(i);
    i++;
}

🧠 Logic:

Initialization → outside
Condition → inside while
Increment → manual

👉 Used when:

Iterations are unknown
Condition-based looping

🔁 For Loop

for(int i = 0; i <= 10; i++) {
    System.out.println(i);
}

🧠 Logic:

Everything in one line:
- init, condition, increment

👉 Used when:

Iterations are known

📤 Output (Both):

0 1 2 3 4 5 6 7 8 9 10

🔹 5. Bonus Insight 💡

🖥️ Ctrl + Shift + I

Auto formats code
Improves readability
Saves time in debugging

🔚 Final Takeaways

✔ % operator is key for divisibility logic
✔ Prime = no divisors between 2 and n-1
✔ Boolean is best for true/false conditions
✔ Reverse logic = extract + rebuild
✔ Loops = backbone of logic building

🔥 The more you trace step-by-step, the stronger your logic becomes!

🤖 A Small Note
I used ChatGPT to help structure and refine this blog while keeping the concepts aligned with my learning.

🚀 Day 24 of My Automation Journey – Looping Statements (While Loop)

bala d kaveri — Fri, 27 Mar 2026 12:31:07 +0000

Today I explored Looping Statements in Java, especially the while loop.

Loops are very important because they help us repeat a task multiple times without writing duplicate code.

🔹 What is a Loop?

👉 A loop is used to execute a block of code repeatedly based on a condition.

🔁 Types of Loops in Java

✔ While Loop
✔ For Loop
✔ Do-While Loop

👉 Today focus: While Loop

🔹 While Loop Syntax

while(condition) {
    // code
}

✔ Condition is checked first
✔ If true → executes
✔ If false → stops

🔍 Scenario 1: Print same number multiple times
❓ Question

Print 1 five times

int i = 1;

while(i <= 5) {
    System.out.print(1 + " ");
    i++;
}

📤 Output

1 1 1 1 1

✅ Explanation

✔ Loop runs 5 times
✔ Always prints 1

🔍 Scenario 2: Print numbers from 1 to 5
❓ Question

Print numbers from 1 to 5

int i = 1;

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

📤 Output

1 2 3 4 5

✅ Explanation

✔ i increases each time
✔ Prints updated value

🔍 Scenario 3: Print odd numbers
❓ Question

Print odd numbers from 1 to 10

int i = 1;

while(i <= 10) {
    if(i % 2 != 0) {
        System.out.print(i + " ");
    }
    i++;
}

📤 Output

1 3 5 7 9

✅ Explanation

✔ i % 2 != 0 → odd numbers
✔ Even numbers skipped

🔍 Scenario 4: Multiplication Table (×5)
❓ Question

Print multiplication table of 5

int i = 1;

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

📤 Output

✅ Explanation

✔ Loop runs 5 times
✔ Multiplies i * 5

🔍 Scenario 5: Multiples of 3 AND 5
❓ Question

Print numbers divisible by both 3 and 5

int i = 1;

while (i <= 30) {
    if (i % 3 == 0 && i % 5 == 0)
        System.out.println(i);
    i++;
}

📤 Output

15
30

✅ Explanation

✔ && → both conditions must be true
✔ Only multiples of 15 printed

🔍 Scenario 6: Multiples of 3 OR 5
❓ Question

Print numbers divisible by 3 OR 5

int i = 1;

while (i <= 10) {
    if (i % 3 == 0 || i % 5 == 0)
        System.out.println(i);
    i++;
}

📤 Output

✅ Explanation

✔ || → any one condition true
✔ More numbers printed

🔍 Scenario 7: Multiple Conditions with if-else
❓ Question

Print different messages based on divisibility

int i = 1;

while (i <= 20) {

    if (i % 3 == 0 && i % 5 == 0)
        System.out.println(i + " multiply by both");

    else if (i % 3 == 0)
        System.out.println(i + " multiply by 3");

    else if (i % 5 == 0)
        System.out.println(i + " multiply by 5");

    else
        System.out.println(i);

    i++;
}

📤 Output (Sample)

8
9 multiply by 3
10 multiply by 5
11
12 multiply by 3
13
14
15 multiply by both
16
17
18 multiply by 3

✅ Explanation

✔ Priority matters
✔ First matching condition executes

⚠️ Common Mistakes

❌ Forgetting i++ → Infinite loop 😱
❌ Wrong condition → loop never runs
❌ Using = instead of ==

🧠 Key Takeaways

✔ While loop checks condition first
✔ Used when number of iterations is unknown
✔ i++ is very important
✔ && → both conditions
✔ || → any one condition
✔ Can combine with if-else for complex logic

🏁 Conclusion

Today I learned how to use while loop effectively with conditions.

This is very useful in automation for:

✔ Repeating test steps
✔ Data-driven testing
✔ Iterating through elements

Step by step, I’m improving my Java logic for Selenium Automation 🚀

🤖 A Small Note

I used ChatGPT to help structure and refine this blog while ensuring the concepts remain aligned with my trainer’s explanations.