Java新手如何做记账软件教程

class Expense {
    double amount;
    String category;
    String remark;
    String date;
public Expense(double amount, String category, String remark, String date) {
    this.amount = amount;
    this.category = category;
    this.remark = remark;
    this.date = date;
}

@Override
public String toString() {
    return date + " | " + category + " | ¥" + amount + " | " + remark;
}
}

import java.util.*;
public class AccountingApp {
private List records = new ArrayList<>();
private Scanner scanner = new Scanner(System.in);
public void start() {
    while (true) {
        System.out.println("\n--- 记账小应用 ---");
        System.out.println("1. 添加记录");
        System.out.println("2. 查看所有记录");
        System.out.println("3. 按类别查询");
        System.out.println("4. 退出");
        System.out.print("请选择：");

        int choice = scanner.nextInt();
        scanner.nextLine(); // 吃掉换行

        switch (choice) {
            case 1 -> addRecord();
            case 2 -> showAll();
            case 3 -> searchByCategory();
            case 4 -> {
                System.out.println("再见！");
                return;
            }
            default -> System.out.println("无效选择");
        }
    }
}

private void addRecord() {
    System.out.print("金额：");
    double amount = scanner.nextDouble();
    scanner.nextLine();
    System.out.print("类别（餐饮、交通等）：");
    String category = scanner.nextLine();
    System.out.print("备注：");
    String remark = scanner.nextLine();
    String date = new Date().toString().substring(0, 10); // 简单日期

    records.add(new Expense(amount, category, remark, date));
    System.out.println("已添加！");
}

private void showAll() {
    if (records.isEmpty()) {
        System.out.println("暂无记录。");
    } else {
        for (Expense e : records) {
            System.out.println(e);
        }
    }
}

private void searchByCategory() {
    System.out.print("输入类别：");
    String cat = scanner.nextLine();
    boolean found = false;
    for (Expense e : records) {
        if (e.category.equals(cat)) {
            System.out.println(e);
            found = true;
        }
    }
    if (!found) System.out.println("无匹配记录。");
}

public static void main(String[] args) {
    new AccountingApp().start();
}
}