类中的java构造函数不能应用于给定的类型 [英] java constructor in class cannot be applied to given types

问题描述

我有2个子类：Staff，Student
他们属于超类Person。

I have 2 subclasses: Staff, Student they belong to superclass Person.

这是我老师给出的代码（任务）：

Here is the code(tasks) which is given by my teacher:

public class Person
{

   private String name;
   private int yearOfBirth;

   /**
    * Create a person with given name and age.
    */
   Person(String name, int yearOfBirth)
   {
      this.name = name;
      this.yearOfBirth = yearOfBirth;
   }
}

---

---

class Student extends Person
{

   private String SID;    // student ID number

   /**
    * Create a student with no parameters.
    */

   Student()
   {
    //task.
   }
}

---

---

public class Staff extends Person
{

   private String roomNumber;

   /**
    * Construct a staff member with field values and no pamaeters.
    */
   public Staff()
   {
    //task 
   }
}

我不知道为了创建没有参数的对象我可以键入什么。
它总是出现如下错误：构造函数类Person中的Person不能应用于给定的类型; required：java.lang.String，int;

I don't know what can I type in order to create an object without parameter. It always appears an error like: constructor Person in class Person cannot be applied to given types; required: java.lang.String,int;

我在网上查了解有两种解决问题的方法：

I have checked online that there are 2 ways to solve the problem:

1. 在超类中添加一个默认值：Person（）//不带参数。
   在子类Student：

1. add a default value in the superclass: Person()//without parameter. In the subclass Student:

Student（）
{
Person astudent = new Student（）/ /我猜。
}

在子类中添加super（）：
学生（）
{
super（xxx）//我猜。
}

add a super() in the subclass: Student() { super("xxx")//I guess. }

我不知道该怎么做。我是学习BlueJ的先驱。
希望有人可以帮助我。非常感谢。

I don't know what to do. I an a starter in learning BlueJ. Hope anyone can help me. Thank you very much.

推荐答案

因为你的超级人没有'在你的子类（ Student 和 Staff ）中有一个默认构造函数，你必须调用超类构造函数第一个语句。

Since your super class Person doesn't have a default constructor, in your sub classes (Student and Staff), you must call the super class constructor as the first statement.

你应该像这样定义你的子类构造函数：

You should define your sub class constructors like this:

Student() {
    super("a_string_value", an_int_value);// You have to pass String and int values to super class
}

---

---

Staff() {
    super("a_string_value", an_int_value); // You have to pass String and int values to super class
}

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