Java继承和super()不能按预期工作 [英] Java inheritance and super() isn't working as expected

问题描述

对于一项家庭作业，我正在从事以下工作.从长远来看，这是一个分配的类结构，我知道这不是最佳的设计.

For a homework assignment, I'm working with the following. It's an assigned class structure, I know it's not the best design by a long shot.

Class           | Extends         | Variables
--------------------------------------------------------
Person          | None            | firstName, lastName, streetAddress, zipCode, phone
CollegeEmployee | Person          | ssn, salary,deptName
Faculty         | CollegeEmployee | tenure(boolean)
Student         | person          | GPA,major

所以在教师班上...

So in the Faculty class...

 public class Faculty extends CollegeEmployee
 {
      protected String booleanFlag;
      protected boolean tenured;
      public Faculty(String firstName, String lastName, String streetAddress,
                     String zipCode, String phoneNumber,String ssn,
                     String department,double salary)
      { 
           super(firstName,lastName,streetAddress,zipCode,phoneNumber,
                 ssn,department,salary);
           String booleanFlag = JOptionPane.showInputDialog
                                (null, "Tenured (Y/N)?");
           if(booleanFlag.equals("Y"))
           tenured = true;
           else
           tenured = false;
       }
 }

据我了解，Faculty中的super()将允许访问CollegeEmployee和Person中的变量.使用上面的代码，当我仅包含Person变量时，它可以正常编译.尝试使用ssn, department, or salary时，立即出现以下编译错误.

It was my understanding that super() in Faculty would allow access to the variables in CollegeEmployee as well as Person. With the code above, it compiles fine when I ONLY include the Person variables. As soon as I try to use ssn, department, or salary I get the following compile errors.

 Faculty.java:15: error: constructor CollegeEmployee in class CollegeEmployee can not be applied to the given types:
            super(firstName,lastName,streetAddress,zipCode,phoneNumber,ssn,department,salary);
                                                                                            ^
Required: String,String,String,String,String
   Found: String,String,String,String,String,String,String,String
  reason: actual and formal argument lists differ in length

这个错误让我完全困惑...这是实际的还是形式上的? Person有五个参数，CollegeEmployee有3个参数，所以我猜想参数传递的方式有些奇怪...但是我不太确定从哪里开始修复它.我想念什么?

I'm completely confused by this error...which is the actual and formal? Person has five arguments, CollegeEmployee has 3, so my guess is that something's funky with how the parameters are being passed...but I'm not quite sure where to begin fixing it. What am I missing?

这是我的CollegeEmployee班

Here's my CollegeEmployee class

 import java.util.*;
 import javax.swing.*;
 //
 public class CollegeEmployee extends Person
 {
     protected String ssn;
     protected String sal;
     protected double annSalary;
     protected String department;
 //
     public CollegeEmployee(String firstName, String lastName, 
                            String streetAddress, String zipCode, 
                            String phoneNumber)
     {
          super(firstName,lastName,streetAddress,zipCode,phoneNumber);
          ssn = JOptionPane.showInputDialog(null, "Enter SSN ");
          department = JOptionPane.showInputDialog
                       (null, "Enter department: ");
          sal = JOptionPane.showInputDialog(null, "Enter salary: ");
         annSalary = Double.parseDouble(sal);
     }
 //
     public void setSSN(String ssn)
     {         this.ssn = ssn;         }
     public void setAnnSalary(double annSalary)
     {        this.annSalary = annSalary;     }
     public void setDepartment(String department)
     {        this.department = department;    }
 //
     public String getSSN()
     {        return ssn;                }
     public double getAnnSalary()
     {        return annSalary;          }
     public String getDepartment()
     {        return department;         }
 //
     public void display()
     {
         super.display();
         JOptionPane.showMessageDialog
         (null, "\nSSN: " + getSSN() + "\nAnnual Salary: " 
          + getAnnSalary() + "\nDepartment: " + getDepartment(), 
          "Information", JOptionPane.QUESTION_MESSAGE);
     }
 }

推荐答案

您在构造函数的结尾意外创建了;:

You made an accidental ; at the end of your constructor:

      public Faculty(String firstName, String lastName, String streetAddress,   String zipCode, String phoneNumber,String ssn,
           String Department,double salary); // <--- this has to go

并在注释中指出，您的构造函数中有String Department，但您传递了department(大写不正确)，请将构造函数参数重命名为String department

And as pointed out in a comment you have String Department in your constructor, but you pass department (incorrect capitalization), rename your constructor argument to String department

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