Mata Kuliah PBO Pertemuan Ke-6

Introduction

This tutorial focuses on building a simple object-oriented transaction application using the principles of Inheritance and Encapsulation. These concepts are fundamental in object-oriented programming (OOP) and will help you understand how to structure your applications effectively.

Step 1: Understanding Object-Oriented Programming Concepts

Familiarize yourself with the key OOP concepts that will be applied in this tutorial:

• Encapsulation: This principle involves bundling the data (attributes) and methods (functions) that operate on the data into a single unit or class. It helps in restricting access to certain components, which can prevent unintended interference and misuse.

• Inheritance: This allows a new class (subclass) to inherit properties and behaviors (methods) from another class (superclass). It promotes code reusability and establishes a hierarchy between classes.

Step 2: Setting Up Your Development Environment

Before you start coding, ensure your development environment is ready:

• Install a suitable code editor (e.g., Visual Studio Code, IntelliJ IDEA).
• Make sure you have the necessary programming language installed (e.g., Java, Python).
• Set up any required libraries or frameworks that might assist in building your application.

Step 3: Designing Your Classes

Design the classes that will represent your application. Consider the following:

• Create a Base Class: This will hold common attributes and methods.

  • For example, create a class named Transaction that includes attributes like transactionID, amount, and date.

• Create Inherited Classes: Extend the base class for specific types of transactions.

  • For example, create a class Purchase that inherits from Transaction and includes additional methods specific to purchasing behavior.

Example Code for Classes

class Transaction {
    private String transactionID;
    private double amount;
    private String date;

    // Constructor
    public Transaction(String transactionID, double amount, String date) {
        this.transactionID = transactionID;
        this.amount = amount;
        this.date = date;
    }

    // Getters for encapsulated data
    public String getTransactionID() {
        return transactionID;
    }
    
    public double getAmount() {
        return amount;
    }
}

class Purchase extends Transaction {
    private String item;

    public Purchase(String transactionID, double amount, String date, String item) {
        super(transactionID, amount, date);
        this.item = item;
    }

    // Additional methods specific to Purchase
    public void displayPurchaseInfo() {
        System.out.println("Item: " + item + ", Amount: " + getAmount());
    }
}

Step 4: Implementing the Application Logic

Now that your classes are set up, implement the application logic:

• Create Instances: Instantiate your classes and perform operations.
• Manage Transactions: Create methods to process and manage transactions, such as adding new transactions and displaying transaction details.

Example Code for Application Logic

public class Main {
    public static void main(String[] args) {
        Purchase purchase = new Purchase("T001", 150.75, "2023-10-01", "Laptop");
        purchase.displayPurchaseInfo();
    }
}

Step 5: Testing Your Application

Once the application logic is implemented, conduct thorough testing:

• Unit Testing: Create tests for each class and method to ensure they work as expected.
• Integration Testing: Test how different classes interact with one another.

Conclusion

In this tutorial, you learned how to apply the principles of Inheritance and Encapsulation to build a simple transaction application. By understanding these concepts, you can create well-structured, efficient, and reusable code.

Next steps include exploring more advanced OOP concepts, such as polymorphism and interfaces, or expanding your application with additional features like user authentication or data storage.