**Course Title:** Comprehensive Java Programming: From Basics to Advanced Concepts **Section Title:** Object-Oriented Programming (OOP) Concepts in Java **Topic:** Design a simple class with attributes and methods, and create objects to interact with the class.(Lab topic) ### Overview In this lab, we will design a simple class called `BankAccount` with attributes and methods, and create objects to interact with the class. This exercise will help you understand how to create classes and objects, and how to use them to perform operations. ### Designing the BankAccount Class Let's start by defining the `BankAccount` class. A bank account typically has attributes like account number, account holder's name, and balance. It also has methods like deposit, withdraw, and check balance. Here's a simple implementation: ```java // BankAccount.java public class BankAccount { private int accountNumber; private String accountHolderName; private double balance; public BankAccount(int accountNumber, String accountHolderName, double balance) { this.accountNumber = accountNumber; this.accountHolderName = accountHolderName; this.balance = balance; } // Getter and setter methods public int getAccountNumber() { return accountNumber; } public void setAccountNumber(int accountNumber) { this.accountNumber = accountNumber; } public String getAccountHolderName() { return accountHolderName; } public void setAccountHolderName(String accountHolderName) { this.accountHolderName = accountHolderName; } public double getBalance() { return balance; } public void setBalance(double balance) { this.balance = balance; } // Method to deposit money public void deposit(double amount) { if (amount > 0) { balance += amount; System.out.println("Deposit successful. New balance: " + balance); } else { System.out.println("Invalid deposit amount."); } } // Method to withdraw money public void withdraw(double amount) { if (amount > 0 && balance >= amount) { balance -= amount; System.out.println("Withdrawal successful. New balance: " + balance); } else { System.out.println("Invalid withdrawal amount."); } } // Method to check balance public void checkBalance() { System.out.println("Current balance: " + balance); } } ``` ### Creating Objects and Interacting with the Class Now that we have designed the `BankAccount` class, let's create objects and interact with the class. Here's an example: ```java // Main.java public class Main { public static void main(String[] args) { // Create a new BankAccount object BankAccount account1 = new BankAccount(12345, "John Doe", 1000.0); // Deposit money account1.deposit(500.0); // Withdraw money account1.withdraw(200.0); // Check balance account1.checkBalance(); // Create another BankAccount object BankAccount account2 = new BankAccount(67890, "Jane Doe", 500.0); // Deposit money account2.deposit(1000.0); // Withdraw money account2.withdraw(300.0); // Check balance account2.checkBalance(); } } ``` ### Key Concepts * **Attributes**: These are the data members of a class, which are used to describe the state of an object. In our example, `accountNumber`, `accountHolderName`, and `balance` are the attributes of the `BankAccount` class. * **Methods**: These are the functions of a class, which are used to perform operations on the attributes. In our example, `deposit`, `withdraw`, and `checkBalance` are the methods of the `BankAccount` class. * **Objects**: These are instances of a class, which have their own set of attributes and methods. In our example, `account1` and `account2` are objects of the `BankAccount` class. * **Encapsulation**: This is the concept of hiding the internal details of an object from the outside world and only exposing the necessary information through public methods. In our example, the attributes of the `BankAccount` class are private, and we use public methods to access and modify them. ### Practical Takeaways * Use meaningful and descriptive names for attributes and methods to make your code more readable and maintainable. * Use encapsulation to hide the internal details of an object and expose only the necessary information through public methods. * Use constructors to initialize the attributes of an object when it is created. * Use methods to perform operations on the attributes of an object. ### Resources * Oracle Documentation: [Objects and Classes](https://docs.oracle.com/javase/tutorial/java/javaOO/index.html) * Java Tutorials Point: [Java Class and Objects](https://www.tutorialspoint.com/java/java_classes_objects.htm) * Java Brains: [Java Classes and Objects](https://www.youtube.com/watch?v=SJ-zzJ7GcMA&list=PLsyeobzWxl7raON0ZJm3CJu7WYRxO5RjT&index=12) Feel free to ask any questions or share your thoughts on this topic in the comments below.