Introduction to Java Basics to Practical Applications: Object-Oriented Practical Design

Object-oriented programming (OOP) is a programming paradigm that introduces objects and classes into code to facilitate the development of large software systems. This article introduces the practical application of object-oriented design through a bank account system case: Define classes and objects: Divide system functions into classes and objects, for example, the BankAccount class represents a bank account. Create and use objects: Create a BankAccount object and operate it using methods such as deposit, withdrawal, and balance query. Modularity and maintainability: By separating data and operations into classes and objects, the scalability, reusability and ease of maintenance of the code are achieved.

Java Basics to Practical Application: Object-Oriented Practical Design

Object-oriented programming (OOP) is a programming paradigm. It introduces the concepts of objects and classes into code, making it easier to develop and maintain large software systems. This article will provide a practical case to help you understand the basics of object-oriented design.

Case: Design a bank account system

Consider a bank account system that contains the following main functions:

• Create an account
• Deposit
• Withdrawal
• Check balance

Design classes and objects

The first step is to define Classes and objects in the system. A bank account can be represented as a class, which contains account information and operation methods.

public class BankAccount {
    private int accountNumber;
    private double balance;

    // Constructor
    public BankAccount(int accountNumber, double balance) {
        this.accountNumber = accountNumber;
        this.balance = balance;
    }

    // Methods
    public void deposit(double amount) {
        balance += amount;
    }

    public void withdraw(double amount) {
        if (amount <= balance) {
            balance -= amount;
        }
    }

    public double getBalance() {
        return balance;
    }
}

Creating and using objects

Next, we can create BankAccount objects and perform operations with them.

// 创建一个账户对象
BankAccount account = new BankAccount(123456789, 1000.0);

// 存入 500 元
account.deposit(500.0);

// 取款 300 元
account.withdraw(300.0);

// 查询余额
double balance = account.getBalance();
System.out.println("账户余额：" + balance);

Output results:

账户余额：1200.0

By using classes and objects to separate data and operations in the code, we create a modular and easy-to-maintain bank account system.

Conclusion

Object-oriented design is a powerful method for building complex systems in Java. By understanding the concepts of classes, objects, and methods, you can design code that is extensible, reusable, and easy to understand.

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