Java开发网 - 关于内部类

Topic: 关于内部类

1.关于内部类

Posted by: floweret
Posted on: 2002-12-02 22:45

假设有个top-level class 叫OuterClass,OuterClass中有个member class叫InnerClass,如果我要创建InnerClass的实例就必须用如下语句：
InnerClass objInnerClass=new OuterClass().new InnerClass();

假设还有个top-level class也叫InnerClass,并且和OuterClass在同一个目录夹下，设置为同一个package中的类，因为编译OuterClass产生两个class文件是OuterClass.java和OuterClass$InnerClass.java,编译top-leve InnerClass将产生InnerClass.java

现在我要在OuterClass中创建top-level InnerClass的实例，如果按一般的写法 InnerClass objI=new InnerClass();编译时就产生如下信息：
non-static variable this cannot be referenced from a static context

如果这两个类名相同的话，我如何能创建top-level InnerClass的实例呢？

2.How about this [Re: floweret]	Copy to clipboard
Posted by: snowbug Posted on: 2002-12-02 23:06 Did you try this: package1.InnerClass obj1 = new package1.InnerClass();

3.Re:关于内部类 [Re: floweret]	Copy to clipboard
Posted by: floweret Posted on: 2002-12-02 23:30 还是不行是不是Java对此有限制，同一个包中top-level class 和 inner class不能同名呢

4.I c [Re: floweret]	Copy to clipboard
Posted by: snowbug Posted on: 2002-12-03 10:21 Oh, I see, the problem you have is not because of creating the class, It has something to do with the static and non-static references. I just did a quick try and it worked with no problem. Could you please post you code here (just the relavent part)?

5.Re:关于内部类 [Re: floweret]

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Posted by: floweret
Posted on: 2002-12-03 10:49

我就是在看内部类时，自己突发奇想，如果创建一个非static的member class,并且和同一个包中的top-level class同名，jvm如何区分我到底要创建哪个类的实例，并无实际的代码 Tongue


OuterClass.java

class OuterClass{
  class InnerClass{}
  public static void main(){
     new InnerClass=new OuterClass.new InnerClass();       
     //这里如何创建一个top-level的InnerClass的实例呢
  }
}

InnerClass.java

class InnerClass{}

这两个文件是放在同一文件夹下的

6.Re:关于内部类 [Re: floweret]

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Posted by: snowbug
Posted on: 2002-12-03 12:14

Top Level Class Bar:


package pkg;
public class Bar {
    public static void print(){
        System.out.println("Top Class Bar");
    }
}

Inner Class Bar:


package pkg;
public class Foo {

    static class Bar{
        public void print(){
            System.out.println("Foo.Bar");
        }
    }

/*
    //non-static version
    class Bar{
        public void print(){
            System.out.println("Foo.Bar (non-static)");
        }
    }
*/

    public static void main(String[] args) {
        new Bar().print();  //calls the inner class Bar
        //new Foo.new Bar().print();  //calls the inner class Bar, non-static version
        new pkg.Bar().print();  //calls the top level class Bar
    }
}