Java开发记账本应用教程

public class Record {
    private double amount;
    private String type; // "收入" 或 "支出"
    private String category;
    private String remark;
    private String date;
public Record(double amount, String type, String category, String remark, String date) {
    this.amount = amount;
    this.type = type;
    this.category = category;
    this.remark = remark;
    this.date = date;
}

// Getter 和 Setter 方法（可自动生成）
@Override
public String toString() {
    return date + " | " + type + " | " + category + " | ¥" + amount + " | " + remark;
}
}

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

public void addRecord() {
    System.out.print("金额: ");
    double amount = scanner.nextDouble();
    System.out.print("类型(收入/支出): ");
    String type = scanner.next();
    System.out.print("分类: ");
    String category = scanner.next();
    System.out.print("备注: ");
    String remark = scanner.next();
    String date = new Date().toString();

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

public void viewRecords() {
    if (records.isEmpty()) {
        System.out.println("暂无记录。");
        return;
    }
    for (Record r : records) {
        System.out.println(r);
    }
}

public void showSummary() {
    double income = 0, expense = 0;
    for (Record r : records) {
        if ("收入".equals(r.getType())) {
            income += r.getAmount();
        } else if ("支出".equals(r.getType())) {
            expense += r.getAmount();
        }
    }
    System.out.println("总收入: ¥" + income);
    System.out.println("总支出: ¥" + expense);
    System.out.println("余额: ¥" + (income - expense));
}
}

import java.io.*;
// 保存数据到文件
public void saveToFile(String filename) throws IOException {
try (BufferedWriter writer = new BufferedWriter(new FileWriter(filename))) {
for (Record r : records) {
writer.write(String.join(",", 
r.getAmount()+"", r.getType(), r.getCategory(), r.getRemark(), r.getDate()));
writer.newLine();
}
}
}
// 从文件加载数据
public void loadFromFile(String filename) throws IOException {
File file = new File(filename);
if (!file.exists()) return;
try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
    String line;
    while ((line = reader.readLine()) != null) {
        String[] parts = line.split(",");
        if (parts.length == 5) {
            Record r = new Record(
                Double.parseDouble(parts[0]),
                parts[1], parts[2], parts[3], parts[4]
            );
            records.add(r);
        }
    }
}
}

public static void main(String[] args) {
    Ledger ledger = new Ledger();
try {
    ledger.loadFromFile("ledger.csv");
} catch (IOException e) {
    System.out.println("无法加载历史数据：" + e.getMessage());
}

Scanner scanner = new Scanner(System.in);
while (true) {
    System.out.println("\n--- 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. 查看统计");
    System.out.println("4. 保存并退出");
    System.out.print("请选择: ");

    int choice = scanner.nextInt();
    switch (choice) {
        case 1 -> ledger.addRecord();
        case 2 -> ledger.viewRecords();
        case 3 -> ledger.showSummary();
        case 4 -> {
            try {
                ledger.saveToFile("ledger.csv");
                System.out.println("数据已保存，再见！");
            } catch (IOException e) {
                System.out.println("保存失败：" + e.getMessage());
            }
            return;
        }
        default -> System.out.println("无效选择，请重试。");
    }
}
}