Question

我有一个员工班：

public abstract class Employee {

private String firstName;
private String lastName;
private int joinYear, joinMonth, joinDay;
LocalDate startDate;
static int idCounter=0;
private double employeeId;
private double numEmployees;
Employee[] employeeArray = new Employee[10];
private double monthlyEarnings;
// constructor
public Employee(String first, String last, int year, int month, int day) {
    firstName = first;
    lastName = last;
    joinYear=year;
    joinMonth=month;
    joinDay=day;
    startDate= new LocalDate(joinYear, joinMonth, joinDay);
    this.monthlyEarnings=0;
    this.setEmployeeId(idCounter);
    employeeArray[idCounter]=this;
    idCounter++;
    numEmployees++;
}
}

如上所示，在构造函数中，创建employee对象时，会将其添加到employeeArray：employeeArray[idCounter]=this;

然后，当我尝试在main方法中访问数组的成员时，我收到错误“employeeArray无法解析为变量”

public class Test {

// test Employee hierarchy
public static void main(String args[]) {
Employee Employee1 = new Employee("John", "Smith", 1997, 8, 20);
Employee Employee2 = new Employee("Bob", "Oak", 1999, 6, 20);


System.out.println(employeeArray[1]); //error here
}
}

Answer 1

显然employeeArray超出了主要范围。您需要使用(instance of Employee).employeeArray引用它。

然而，由于您的类Employee的逻辑被破坏，这在您的情况下是无关紧要的。问题是，idCounter的所有实例都不会共享您的employeeArray和Employee变量。相反，每个Employee实例都有自己的列表和计数器（您似乎并不想要）。

事实上，您需要在类本身内创建一个{strong>静态数组Employee。在我看来，使用List<Employee>代替Employee[]更合适，因为您（可能）事先并不知道您需要存储多少员工。

以下是你应该围绕

设计课程的内容

public class Employee {
    private static List<Employee> employees = new ArrayList<>();

    // Your instance fields here
    int employeeId;


    public Employee() {
        // Constructor stuff
        this.employeeId = employees.size();

        employees.add(this); // Add the new employee to the list
    }

    public static List<Employee> getEmployees() {
        return employees;
    }
}

Answer 2

此错误为真：

employeeArray无法解析为变量

您的测试中未定义employeeArray。

您必须从Employee课程中获取该实例。

示例：

System.out.println(Employee1.employeeArray[1]);

数组无法解析为变量 - Java

2 个答案: