Java Study Note:Reference and Object

kevin_chn

于 2004-07-25 00:03:00 发布

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分类专栏： Thinking in Java 文章标签： reference java interface constructor class object

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博主作为Java编程新手，分享了对引用和对象关系、引用与指针区别及向上转型的理解。向上转型很有用，既能隐藏派生类实现，又能使用实现接口的匿名类，文中还给出了相关代码示例展示向上转型和匿名类的应用。

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I never refuse to confess that I am a newbie of Java programming.

It took me some time to understand the connection between reference and object, the difference between reference and pointer ( I learned the concept in C/C++) and the magnificant usage of upcasting.

Upcasting is really a very useful concept that every Javer must keep it in mind. It can not only help hide implementation of the derived class ,but make it possible to use anonymous class that implements an interface, as I will show you below:

interface I {
void play();
}

public class C {
  private I go() {
      return new I() {
         {//Instant Initializer, just like constructor}
         public void play() {
            System.out.println("play()");
         }
      };
   }
   public static void main(String[] args) {
      C c=new C();
      I i=c.go();
      i.play();
   }
}