Java替代说明 [英] Java override explanation

问题描述

这是我的代码

class Glyph { 
  void draw() { System.out.println("Glyph.draw()"); } 
  Glyph(int i) { 
    System.out.println("Glyph() before draw()"); 
    draw(); 
    System.out.println("Glyph() after draw()"); 
  } 
}  

class RoundGlyph extends Glyph { 
  private int radius = 1; 
  RoundGlyph(int r) { 
      super(r);
    radius = r; 
    System.out.println("RoundGlyph.RoundGlyph(), radius = " + radius); 
  } 
  void draw() { 
      System.out.println("RoundGlyph.draw(), radius = " + radius); 
  } 
}  

public class PolyConstructors { 
  public static void main(String[] args) {
  new RoundGlyph(5); 
  } 
} 

输出:

Glyph() before draw()
RoundGlyph.draw(), radius = 0
Glyph() after draw()
RoundGlyph.RoundGlyph(), radius = 5

为什么超类Glyph的构造函数调用子类RoundGlyph的draw方法?如何从超类的构造函数中调用超类的draw方法?我试过了，但是没用....

Why is the constructor of the superclass Glyph calling the draw method of the subclass RoundGlyph? How can I call the draw method of the superclass from the constructors of the superclass? I tried this but it didn't work....

推荐答案

为什么子类的超级调用draw方法的构造方法

Why the Constructors of super calling draw method of sub classs

这是方法覆盖起作用的方式.如果子类实现了与其父(或祖父母等)具有相同签名的方法，则当其祖先之一调用该方法而未指定super.时，将调用该子类的版本.

This is the way that method overriding works. If a subclass has implemented a method with the same signature as its parent (or grandparent, etc), when one of its ancestors calls that method without specifying super., the sublcass's version will be called.

我将如何从super的构造函数中调用super的方法

how i will be able to call method of super from Constructors of super

与子类的版本相反，没有一种方法可以指定调用方法的 my 版本.

There isn't a way to specify calling my version of a method, as opposed to a subclass's version.

请注意，除了设置类所必需的之外，您不应在构造函数中进行任何工作.

Please note that you shouldn't do any work in a constructor other than what is necessary to set up the class.

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