Java中跨类访问对象属性：泛型与类型安全深度解析

public class Main {
    public static void main(String[] args) {
        Employees employees = new Employees();
        employees.addEmployee("Orlando", "Silva", 111111111, "St. King's Street", 111111111, 11111111111111L, employees.getMinimumWage(), employees.getDayShift());
        // ... 添加更多员工
    }
}

import java.util.ArrayList;

public class Employees {
    // 员工属性（简化）
    public String name;
    // ... 其他属性和方法

    private ArrayList<Employees> employeesArrayList = new ArrayList<>(); // 存储员工列表
    private AllStaff allStaff = new AllStaff(); // AllStaff实例

    // 构造函数
    public Employees() {}

    public Employees(String name, String lName, int nID, String address, int phNum, long nSocialSecNum, double minimumWage, String shift) {
        this.name = name;
        // ... 初始化其他属性
    }

    // 添加员工方法
    public void addEmployee(String name, String lName, int nID, String address, int phNum, long nSocialSecNum, double minimumWage, String shift) {
        Employees employee = new Employees(name, lName, nID, address, phNum, nSocialSecNum, minimumWage, shift);
        employeesArrayList.add(employee);
        addToAllStaff(); // 将列表传递给AllStaff
    }

    // 内部方法，演示在传递前可以访问属性
    void addToAllStaff() {
        System.out.println("(Class Employees) employees size: " + employeesArrayList.size());
        for (int i = 0; i < employeesArrayList.size(); i++) {
            System.out.println("Employee names: " + employeesArrayList.get(i).name); // 在这里可以正常访问
        }
        allStaff.addEmployees(employeesArrayList); // 传递列表
    }

    // Getter方法 (例如 getName())
    public String getName() {
        return name;
    }
    // ... 其他getter/setter
}

import java.util.ArrayList;

public class AllStaff {
    // 静态列表，用于存储员工数据
    static ArrayList<AllStaff> employeesArrayList; // 注意这里的类型声明

    public AllStaff() {}

    // 接收员工列表的方法
    public void addEmployees(ArrayList listOfEmployees) { // 注意这里的参数类型
        System.out.println("List of employees size: " + listOfEmployees.size());

        for (int i = 0; i < listOfEmployees.size(); i++) {
            // 尝试访问属性，但可能失败或需要强制类型转换
            // System.out.println("Employee names: " + listOfEmployees.get(i).getName()); // 编译错误或运行时错误
            // System.out.println("Employee names: " + listOfEmployees.get(i).name);    // 编译错误或运行时错误
        }
        this.employeesArrayList = listOfEmployees; // 赋值
    }
}

import java.util.ArrayList;

public class Employees {
    public String name; // 示例中为public，实际开发中建议使用private并提供getter/setter
    private String lName;
    private int nID;
    // ... 其他属性

    private ArrayList<Employees> employeesArrayList = new ArrayList<>();
    private AllStaff allStaff = new AllStaff();

    public Employees() {}

    public Employees(String name, String lName, int nID, String address, int phNum, long nSocialSecNum, double minimumWage, String shift) {
        this.name = name;
        this.lName = lName;
        this.nID = nID;
        // ... 初始化其他属性
    }

    public void addEmployee(String name, String lName, int nID, String address, int phNum, long nSocialSecNum, double minimumWage, String shift) {
        Employees employee = new Employees(name, lName, nID, address, phNum, nSocialSecNum, minimumWage, shift);
        employeesArrayList.add(employee);
        addToAllStaff();
    }

    void addToAllStaff() {
        System.out.println("(Class Employees) employees size: " + employeesArrayList.size());
        for (int i = 0; i < employeesArrayList.size(); i++) {
            System.out.println("Employee names (in Employees class): " + employeesArrayList.get(i).getName());
        }
        allStaff.addEmployees(employeesArrayList);
    }

    // 必须有getter方法才能在外部通过getName()访问
    public String getName() {
        return name;
    }
    // ... 其他getter/setter
}

import java.util.ArrayList;

public class AllStaff {
    // 静态列表，现在明确指定存储Employees对象
    static ArrayList<Employees> employeesArrayList;

    public AllStaff() {}

    // 接收员工列表的方法，明确指定泛型类型为Employees
    public void addEmployees(ArrayList<Employees> listOfEmployees) {
        System.out.println("List of employees size (in AllStaff): " + listOfEmployees.size());

        for (int i = 0; i < listOfEmployees.size(); i++) {
            // 现在可以安全地访问Employees对象的属性了
            System.out.println("Employee names (in AllStaff via getter): " + listOfEmployees.get(i).getName());
            // 如果name属性是public的，也可以直接访问
            System.out.println("Employee names (in AllStaff direct access): " + listOfEmployees.get(i).name);
        }

        // 将接收到的列表赋值给静态变量
        AllStaff.employeesArrayList = listOfEmployees;
    }
}