Java实现简易记账本教程详解

public class Entry {
    private String date;      // 记录日期
    private double amount;    // 金额
    private String type;      // 类型：income 或 expense
    private String remark;    // 备注
public Entry(String date, double amount, String type, String remark) {
    this.date = date;
    this.amount = amount;
    this.type = type;
    this.remark = remark;
}

public String getDate() { return date; }
public double getAmount() { return amount; }
public String getType() { return type; }
public String getRemark() { return remark; }

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

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class AccountBook {
private List records;
private Scanner scanner;
public AccountBook() {
    records = new ArrayList<>();
    scanner = new Scanner(System.in);
}

// 添加记录
public void addEntry() {
    System.out.print("日期 (如 2025-04-05): ");
    String date = scanner.nextLine();

    System.out.print("金额: ");
    double amount = Double.parseDouble(scanner.nextLine());

    System.out.print("类型 (income/expense): ");
    String type = scanner.nextLine();

    System.out.print("备注: ");
    String remark = scanner.nextLine();

    records.add(new Entry(date, amount, type, remark));
    System.out.println("记录已添加！");
}

// 查看所有记录
public void viewAll() {
    if (records.isEmpty()) {
        System.out.println("暂无记录。");
        return;
    }
    System.out.println("\n--- 所有记录 ---");
    for (Entry e : records) {
        System.out.println(e);
    }
}

// 统计收支情况
public void showSummary() {
    double income = 0, expense = 0;
    for (Entry e : records) {
        if ("income".equals(e.getType())) {
            income += e.getAmount();
        } else if ("expense".equals(e.getType())) {
            expense += e.getAmount();
        }
    }
    System.out.printf("\n--- 统计 ---\n总收入: %.2f\n总支出: %.2f\n结余: %.2f\n", income, expense, income - expense);
}

// 启动菜单
public void start() {
    while (true) {
        System.out.println("\n=== 简易记账本 ===");
        System.out.println("1. 添加记录");
        System.out.println("2. 查看所有记录");
        System.out.println("3. 显示统计");
        System.out.println("4. 退出");
        System.out.print("请选择: ");

        String choice = scanner.nextLine();
        switch (choice) {
            case "1":
                addEntry();
                break;
            case "2":
                viewAll();
                break;
            case "3":
                showSummary();
                break;
            case "4":
                System.out.println("再见！");
                return;
            default:
                System.out.println("无效选择，请重试。");
        }
    }
}
}

public class Main {
    public static void main(String[] args) {
        AccountBook book = new AccountBook();
        book.start();
    }
}