JavaSE控制台项目

### JavaSE 记账项目 示例 代码 教程 #### 创建记账系统的概述 为了构建一个简单的JavaSE记账系统，可以采用面向对象编程的原则来设计应用程序结构。该应用将允许用户记录收入和支出，并能查看账户余额。 #### 设计实体类 定义两个主要的实体类`Income`（收入）和`Expense`（支出），以及用于管理这些交易的核心业务逻辑的服务层。 ```java // Income.java public class Income { private String description; private double amount; public Income(String description, double amount) { this.description = description; this.amount = amount; } // Getters and Setters... } // Expense.java public class Expense extends Income { public Expense(String description, double amount) { super(description, Math.abs(amount)); // Ensure positive value for expense tracking purposes. } } ``` #### 构建服务层 创建名为`AccountService`的服务类来进行增删查改操作： ```java import java.util.ArrayList; import java.util.List; public class AccountService { List<Income> incomes = new ArrayList<>(); List<Expense> expenses = new ArrayList<>(); public void addIncome(Income income){ incomes.add(income); } public void addExpense(Expense expense){ expenses.add(expense); } public double getBalance(){ double totalIncomes = incomes.stream().mapToDouble(i -> i.getAmount()).sum(); double totalExpenses = expenses.stream().mapToDouble(e -> e.getAmount()).sum(); return totalIncomes - totalExpenses; } // Additional methods like removeTransaction(), listAllTransactions() etc can be added here as needed. } ``` #### 用户界面(UI) 对于控制台版本的应用程序来说，可以通过命令行读取用户的输入并调用相应的服务方法处理数据。这里提供了一个基本框架供参考： ```java import java.util.Scanner; public class MainApp { static Scanner scanner = new Scanner(System.in); public static void main(String[] args) { AccountService accountService = new AccountService(); while(true){ System.out.println("\n--- Menu ---"); System.out.println("1. Add Income"); System.out.println("2. Add Expense"); System.out.println("3. Check Balance"); System.out.println("0. Exit"); int choice = Integer.parseInt(scanner.nextLine()); switch(choice){ case 1: handleAddIncome(accountService); break; case 2: handleAddExpense(accountService); break; case 3: checkBalance(accountService); break; default: System.exit(0); } } } private static void handleAddIncome(AccountService service){ System.out.print("Enter Description: "); String desc = scanner.nextLine(); System.out.print("Enter Amount: "); Double amt = Double.parseDouble(scanner.nextLine()); service.addIncome(new Income(desc, amt)); System.out.println("Income Added Successfully!"); } private static void handleAddExpense(AccountService service){ System.out.print("Enter Description: "); String desc = scanner.nextLine(); System.out.print("Enter Amount: "); Double amt = Double.parseDouble(scanner.nextLine()); service.addExpense(new Expense(desc, amt * (-1))); // Store negative values to represent expenses. System.out.println("Expense Added Successfully!"); } private static void checkBalance(AccountService service){ System.out.printf("Current balance is %.2f\n",service.getBalance()); } } ``` 上述代码展示了如何利用JavaSE开发一个简易版的个人财务管理工具[^1]。通过这种方式学习者能够掌握基础的对象关系映射概念、集合操作技巧以及其他重要的Java特性。