隐式超级构造函数 Person() 未定义.必须显式调用另一个构造函数? [英] implicit super constructor Person() is undefined. Must explicitly invoke another constructor?

问题描述

我正在处理一个项目，但收到错误隐式超级构造函数 Person() 未定义.必须显式调用另一个构造函数"，我不太明白.

I am working on a project and i am getting the error "implicit super constructor Person() is undefined. Must explicitly invoke another constructor" and i don't quite understand it.

这是我的person类:

Here is my person class:

public class Person {
    public Person(String name, double DOB){

    }
}

我的学生类在尝试实现 person 类时，并给它一个教师变量.

And my student class when trying to implement the person class, and giving it an instructor variable.

public class Student extends Person {

    public Student(String Instructor) {

    }

}

推荐答案

如果构造函数没有显式调用超类构造函数，Java 编译器自动插入对无参数的调用超类的构造函数.

If a constructor does not explicitly invoke a superclass constructor, the Java compiler automatically inserts a call to the no-argument constructor of the superclass.

如果超类没有没有参数的构造函数，你会得到一个编译时错误.目的确实有这样的构造函数，所以如果 Object 是唯一的超类，没有问题.

If the super class does not have a no-argument constructor, you will get a compile-time error. Object does have such a constructor, so if Object is the only superclass, there is no problem.

参考:http://docs.oracle.com/javase/教程/java/IandI/super.html:(参见子类构造函数"部分)

Reference: http://docs.oracle.com/javase/tutorial/java/IandI/super.html : (See under section 'SubClass Constructors')

因此，每当处理参数化构造函数时，都会对父构造函数进行 super(parameter1, parameter2 ..) 调用.此外，这个 super() 调用应该是构造函数块中的第一行.

So whenever dealing with parameterized constructors make a super(parameter1, parameter2 ..) call to the parent constructor. Also this super() call should be the FIRST line in your constructor block.

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