Java构造器中的意外循环：理解super()调用与输入逻辑的陷阱

import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;

class Person {
    protected String agentId; // 更好的做法是让这些字段通过构造器初始化
    protected String password;
    protected String address;

    // 构造器只负责初始化成员变量
    public Person(String agentId, String password, String address) {
        this.agentId = agentId;
        this.password = password;
        this.address = address;
    }

    // 可以添加获取字段的方法
    public String getAgentId() { return agentId; }
    public String getPassword() { return password; }
    public String getAddress() { return address; }
}

class Agent extends Person {
    // Agent类特有的字段（如果存在）
    // private String agentSpecificField;

    public Agent(String agentId, String password, String address) {
        super(agentId, password, address); // 只调用父类构造器
        // this.agentSpecificField = agentSpecificField; // 初始化Agent特有字段
    }

    // 示例：登录和操作逻辑应放在方法中，而不是构造器
    public void performAgentActions(Scanner input) {
        System.out.println("[LOGIN]");
        System.out.print("ENTER AGENT ID:");
        int id = input.nextInt();
        System.out.print("ENTER PASSWORD:");
        int pass = input.nextInt();
        input.nextLine(); // 消费掉nextInt()留下的换行符

        if (id == 20860132 && pass == 20020729) {
            System.out.println("[1]ADD CAR");
            System.out.println("[2]SCHEDULE");
            System.out.println("[3]RECORDS");
            int choice2 = input.nextInt();
            input.nextLine(); // 消费掉nextInt()留下的换行符

            if (choice2 == 1) {
                addCarWorkflow(input); // 委托给一个私有方法处理添加汽车的流程
            } else if (choice2 == 2) {
                // schedule logic
            } else if (choice2 == 3) {
                // records logic
            }
        } else {
            System.out.println("INCORRECT PLEASE TRY AGAIN.");
        }
    }

    private void addCarWorkflow(Scanner input) {
        boolean stopFlag = false;
        List<String> cars = new ArrayList<>();
        cars.add("Tayota");
        cars.add("Hillux");
        cars.add("Bugatti");

        do {
            System.out.println("[CARS]");
            System.out.println(cars);
            System.out.print("Enter Car:");
            String car = input.nextLine();
            cars.add(car);
            System.out.println("Would you like to add more?");
            System.out.println("[1]YES");
            System.out.println("[2]NO");
            String choice3 = input.nextLine(); // 注意这里是nextLine()

            addCar(cars); // 将当前汽车列表写入文件

            if (!choice3.equals("1")) { // 比较字符串使用equals()
                stopFlag = true;
            }
        } while (!stopFlag);
    }

    public void addCar(List<String> cars) {
        try (FileWriter fw = new FileWriter("cars.txt", true);
             PrintWriter pw = new PrintWriter(fw)) {
            pw.println(cars);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void schedule(String schedule) {
        try (FileWriter fw = new FileWriter("schedule.txt", true);
             PrintWriter pw = new PrintWriter(fw)) {
            pw.println(schedule);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void records(String record) {
        try (FileWriter fw = new FileWriter("records.txt", true);
             PrintWriter pw = new PrintWriter(fw)) {
            pw.println(record);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

class Customer extends Person {
    private String customerId;

    public Customer(String agentId, String password, String address, String customerId) {
        super(agentId, password, address);
        this.customerId = customerId;
    }

    public void setCustomerId(String customerId) {
        this.customerId = customerId;
    }

    public String getCustomerId() {
        return customerId;
    }

    // 示例：客户操作方法
    public void performCustomerActions(Scanner input) {
        System.out.println("Customer actions for ID: " + customerId);
        // ... 其他客户特有逻辑 ...
    }

    // 文件写入方法保持不变
    public void rentCar(String car) {
        try (FileWriter fw = new FileWriter("cars.txt", true);
             PrintWriter pw = new PrintWriter(fw)) {
            pw.println(car);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void viewSchedule(String schedule) {
        try (FileWriter fw = new FileWriter("schedule.txt", true);
             PrintWriter pw = new PrintWriter(fw)) {
            pw.println(schedule);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void extend(String record) {
        try (FileWriter fw = new FileWriter("records.txt", true);
             PrintWriter pw = new PrintWriter(fw)) {
            pw.println(record);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class Finals {
    public static void main(String[] args) {
        // 推荐只创建一个Scanner实例并在程序中传递使用或作为静态成员
        Scanner input = new Scanner(System.in); 

        System.out.println("欢迎使用系统！");
        System.out.println("[1] 代理 (Agent)");
        System.out.println("[2] 客户 (Customer)");
        System.out.print("请选择您的角色：");

        int choice = -1;
        try {
            choice = input.nextInt();
            input.nextLine(); // 消费掉nextInt()留下的换行符
        } catch (java.util.InputMismatchException e) {
            System.out.println("输入无效，请输入数字1或2。");
            input.nextLine(); // 清除错误输入
            return; // 退出程序或重新提示
        }

        Person user = null; // 定义一个Person类型的引用

        if (choice == 1) {
            // 在这里创建Agent对象
            Agent agent = new Agent("20860132", "h208f32", "San luis");
            user = agent; // 将Agent对象赋值给Person引用
            System.out.println("您选择了代理角色。");
            // 代理的后续操作
            agent.performAgentActions(input);
        } else if (choice == 2) {
            // 在这里创建Customer对象
            System.out.print("请输入客户ID：");
            String customerId = input.nextLine();
            Customer customer = new Customer("默认代理ID", "默认密码", "默认地址", customerId);
            user = customer; // 将Customer对象赋值给Person引用
            System.out.println("您选择了客户角色。");
            // 客户的后续操作
            customer.performCustomerActions(input);
        } else {
            System.out.println("无效的选择。");
        }

        // 确保关闭Scanner
        input.close();
    }
}