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请教：内部类的问题

午夜蓝调

发贴: 6
积分: 0

于 2009-10-17 18:19


class P {
class Contents{
  private int i=11;
  public int value(){return i;}
  }
class Destination{
  private String label;
  Destination(String whereto){
    label=whereto;
    }
  String readLabel(){return label;}
}

public void ship(String dest){
  Contents c=new Contents();
  Destination d=new Destination(dest);
  System.out.println(d.readLabel());
}
public Destination to(String s) {
  return new Destination(s);
  }
public Contents cont(){
  return new Contents();
  
}
public static void main(String[] args) {
P p=new P();
p.ship("sdfsdfsdf");
P q=new P();
P.Contents c=q.cont();
P.Destination d=q.to("78888");
  }

}

这个程序中
public Destination to(String s) {
  return new Destination(s);
  }
public Contents cont(){
  return new Contents();

}
这段声明to和cont方法是什么方法？为什么要声明？前面为什么还要各跟一个Destination和Contents？请教各位高手，谢谢

JiafanZhou edited on 2009-10-23 18:48

作者

Re:请教：内部类的问题 [Re:午夜蓝调]

JiafanZhou

版主

发贴: 736
积分: 61

于 2009-10-23 19:01

午夜蓝调 wrote:
这段声明to和cont方法是什么方法？为什么要声明？前面为什么还要各跟一个Destination和Contents？请教各位高手，谢谢

to() and cont() are methods no difference from other methods of the P class.

PS: consider to give your classes and methods meaningful names will help others to understand code.

Destination and Contents are inner classes of P class. (as your title has already suggested). Some attentions need to be noted when using inner classes.
- Inner classes are members of the class who contains them. So you should just treat them as members.
- Inner classes have visibility control like other members. (you can declare inner classes as private, public and even static)
- The compiled inner class will have the following name: xxx$yyy (where xxx is the "base" class, and yyy is the inner class)
- Invoke the inner classes the same way as invoke a method or a field.
-...

When I was a kid I used to pray every night for a new bike. Then I realized that The Lord doesn't work that way, so I stole one and asked him to forgive me.

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