java - 我对 super() 的用法感到困惑

Question

我知道 super() 是用来从父类中检索实例变量的，但是当我看到代码如下时:

public class novel extends literature {
private String title;
private String writer;
public novel(String title)
{
    super("novel");
    this.title = title;
    this.writer = "Unknow";
}
public novel(String title, String writer)
{
    super("novel");
    this.title = title;
    this.writer = writer;
}
public String getInfo()
{
    return getGenre() + "\nTitle: " + title + "\nWriter: " + writer;
}
public static void main(String[] args)
{
    novel n = new novel("The devil wears prada", "Lauren Weisberger");
    System.out.println(n.getInfo());
}

}

当我看到这个时: super("novel");我很困惑，为什么子类名可以放在 super 方法中？我不知道为什么 this.writer = "unknown"; 在这里是为了什么？为什么不直接将其设置为作家？

很抱歉向你们提出了这么多问题，但非常感谢您提供任何解决方案。

对不起，大家我仍然不完全明白为什么它使用 super (“小说”)？如果我们说小说这里是一个字符串，那么为什么我们使用与“小说类”同名的字符串呢？

Answer 1

super ("novel") 表示您将 String 作为参数传递给父类的构造函数。

this.writer = "Unknow" 表示将字符串值 "Unknow" 传递给当前类实例的成员。你也可以通过例如。 “Mark Twain”，作者的变量值将是“Mark Twain”。

了解更多信息http://docs.oracle.com/javase/tutorial/java/IandI/subclasses.html

示例

//Parentclass

public class Book {

private String genre;
private String isbn;

//As you can see we have two constructors.

//The first with only one argument
public Book (String genre)
    this.genre = genre;
}


//The second one with two arguments
public Book (String genre, String isbn) {
    this.genre = genre;
    this.isbn = isbn;
}

}

//subclass
class Novel extends Book{

public Novel(String isbn)
   
   
   super("novel", isbn);
   //super() has now two arguments, because we are calling the second constructor
   //which has two args. 
   //Now, in the parent class members genre = "novel" and isbn equals the value passed in the
   //child constructor.
   //This is the same as using the parent constructor inner body in this constructor. 
   //Normally the parent constructor gets overwritten on inheritance. 
   //But super makes its possible to use the parent constructor. 


}

更多示例check this super() documentation