内部类的问题

class Outer{
<br> Inner in;
<br> Outer(){ in=new Inner();}
<br> public class Inner
<br> {
<br>  public Inner(){System.out.println("inner of outer");}
<br> }
<br>}
<br>public class SubOuter extends Outer {
<br>class Inner{
<br> public Inner(){System.out.println("inner of subouter");}
<br>}
<br>
<br> public static void main(String[] args) {
<br>  SubOuter.Inner in1=new SubOuter().new Inner();
<br>  Outer.Inner in2=new Outer().new Inner();
<br>
<br> }
<br>
<br>}
<br>谁能帮我讲讲具体的实现步骤，详细点！

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