java如何初始化父类类型的数组？

Question

我有一个名为SeatingPlan的类，它继承自Seat

在SeatingPlan构造函数中，我将初始化为：

public SeatingPlan(int numberOfRows, int numberOfColumns) {
   super();
   rows = numberOfRows;
   columns = numberOfColumns;
   seats = new Seat[rows][columns];  // (Seat [][] seats during variable declarations)
}

座位。爪哇：

public Seat(String subject, int number) {
   courseSubject = subject;
   courseNumber = number;
}

但是我得到了这个错误：

SeatingPlan.java:8: error: 
    constructor Seat in class Seat cannot be applied to given types;
        super();
        ^
      required: String,int
      found: no arguments
      reason: actual and formal argument lists differ in length
    1 error
    [ERROR] did not compile; check the compiler stack trace field for more info

Answer 1

您需要为Seat使用默认的空构造函数，或者需要使用参数super（subject，number）调用super

Answer 2

问题是，在Java中，当您重载构造函数时，编译器将不再自动提供默认构造函数。因此，如果您仍然需要使用它，那么您需要在类中定义它

public class Seat{

    public Seat(){//Implement the no-arg constructor in your class


    }

    public Seat(String subject, int number) {
       courseSubject = subject;
       courseNumber = number;
    }

}

现在，您可以通过SeatingPlan子类访问父类Seat的no-args构造函数

public SeatingPlan(int numberOfRows, int numberOfColumns) {
   super();//Now you can access the no-args constructor of Seat parent class
   rows = numberOfRows;
   columns = numberOfColumns;
   seats = new Seat[rows][columns];  // (Seat [][] seats during variable declarations)
}

Answer 3

您正在调用super()，而您没有不接受参数的默认构造函数。 因此，添加下面的构造函数，它就会工作。或者在super(param, param)调用中添加所需的参数

public Seat() {
}