用java写一个账单管理系统

好的，账单管理系统大概需要实现以下功能：

1. 记录账单信息：包括账单编号、账单类型、账单金额、账单时间等信息；
2. 查询账单信息：可以按照账单编号、账单类型、账单时间等条件查询账单信息；
3. 统计账单信息：可以按照账单类型、账单时间等条件统计账单信息；
4. 修改账单信息：可以修改账单的各项信息；
5. 删除账单信息：可以删除指定的账单信息。

下面是一个简单的 Java 实现：

import java.util.ArrayList;
import java.util.Scanner;

public class BillManagementSystem {
    private static ArrayList<Bill> bills = new ArrayList<>();
    private static Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        boolean exit = false;
        while (!exit) {
            System.out.println("请选择操作：");
            System.out.println("1. 添加账单");
            System.out.println("2. 查询账单");
            System.out.println("3. 统计账单");
            System.out.println("4. 修改账单");
            System.out.println("5. 删除账单");
            System.out.println("0. 退出");

            int choice = scanner.nextInt();
            switch (choice) {
                case 0:
                    exit = true;
                    break;
                case 1:
                    addBill();
                    break;
                case 2:
                    queryBill();
                    break;
                case 3:
                    countBill();
                    break;
                case 4:
                    modifyBill();
                    break;
                case 5:
                    deleteBill();
                    break;
                default:
                    System.out.println("无效操作！");
                    break;
            }
        }
    }

    private static void addBill() {
        System.out.println("请输入账单编号：");
        String id = scanner.next();
        System.out.println("请输入账单类型：");
        String type = scanner.next();
        System.out.println("请输入账单金额：");
        double amount = scanner.nextDouble();
        System.out.println("请输入账单时间（格式为 yyyy-MM-dd）：");
        String time = scanner.next();
        bills.add(new Bill(id, type, amount, time));
        System.out.println("账单添加成功！");
    }

    private static void queryBill() {
        System.out.println("请选择查询方式：");
        System.out.println("1. 按照账单编号查询");
        System.out.println("2. 按照账单类型查询");
        System.out.println("3. 按照账单时间查询");
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                System.out.println("请输入账单编号：");
                String id = scanner.next();
                for (Bill bill : bills) {
                    if (bill.getId().equals(id)) {
                        System.out.println(bill);
                    }
                }
                break;
            case 2:
                System.out.println("请输入账单类型：");
                String type = scanner.next();
                for (Bill bill : bills) {
                    if (bill.getType().equals(type)) {
                        System.out.println(bill);
                    }
                }
                break;
            case 3:
                System.out.println("请输入账单时间（格式为 yyyy-MM-dd）：");
                String time = scanner.next();
                for (Bill bill : bills) {
                    if (bill.getTime().equals(time)) {
                        System.out.println(bill);
                    }
                }
                break;
            default:
                System.out.println("无效操作！");
                break;
        }
    }

    private static void countBill() {
        System.out.println("请选择统计方式：");
        System.out.println("1. 按照账单类型统计");
        System.out.println("2. 按照账单时间统计");
        int choice = scanner.nextInt();
        switch (choice) {
            case 1:
                System.out.println("请输入要统计的账单类型：");
                String type = scanner.next();
                double total = 0;
                for (Bill bill : bills) {
                    if (bill.getType().equals(type)) {
                        total += bill.getAmount();
                    }
                }
                System.out.println(type + " 类型账单总金额为：" + total);
                break;
            case 2:
                System.out.println("请输入要统计的账单时间（格式为 yyyy-MM-dd）：");
                String time = scanner.next();
                double total2 = 0;
                for (Bill bill : bills) {
                    if (bill.getTime().equals(time)) {
                        total2 += bill.getAmount();
                    }
                }
                System.out.println(time + " 时间账单总金额为：" + total2);
                break;
            default:
                System.out.println("无效操作！");
                break;
        }
    }

    private static void modifyBill() {
        System.out.println("请输入要修改的账单编号：");
        String id = scanner.next();
        for (Bill bill : bills) {
            if (bill.getId().equals(id)) {
                System.out.println("请输入新的账单类型（原来的类型为 " + bill.getType() + "）：");
                String type = scanner.next();
                System.out.println("请输入新的账单金额（原来的金额为 " + bill.getAmount() + "）：");
                double amount = scanner.nextDouble();
                System.out.println("请输入新的账单时间（格式为 yyyy-MM-dd，原来的时间为 " + bill.getTime() + "）：");
                String time = scanner.next();
                bill.setType(type);
                bill.setAmount(amount);
                bill.setTime(time);
                System.out.println("账单修改成功！");
                return;
            }
        }
        System.out.println("未找到对应账单！");
    }

    private static void deleteBill() {
        System.out.println("请输入要删除的账单编号：");
        String id = scanner.next();
        for (int i = 0; i < bills.size(); i++) {
            if (bills.get(i).getId().equals(id)) {
                bills.remove(i);
                System.out.println("账单删除成功！");
                return;
            }
        }
        System.out.println("未找到对应账单！");
    }
}

class Bill {
    private String id;
    private String type;
    private double amount;
    private String time;

    public Bill(String id, String type, double amount, String time) {
        this.id = id;
        this.type = type;
        this.amount = amount;
        this.time = time;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public double getAmount() {
        return amount;
    }

    public void setAmount(double amount) {
        this.amount = amount;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }

    @Override
    public String toString() {
        return "账单编号：" + id + "，账单类型：" + type + "，账单金额：" + amount + "，账单时间：" + time;
    }
}

这个实现比较简单，主要是使用了 ArrayList 来保存账单信息，并通过 switch-case 语句来实现不同的操作。你可以根据需要自行扩展功能或改进实现。