No enclosing instance of type PerfHelper is available due to some intermediate constructor invocation

问题

Consider the below code:

class abstract Normal1 extends Something 
{
}

class Outer 
{
  class abstract Inner extends Normal1
  {

  }
}

class General extends Outer.Inner  // Problem occurs at this 
{
}

The error I am getting is "No enclosing instance of type PerfHelper is available due to some intermediate constructor invocation"

My question is can I extend the inner class like above ?

回答1:

Declare the inner class as static and you should be able to extend it:

class outer {
  static abstract class inner extends normal1 { }
}

If inner is not abstract, it's tied to outer, and can only exist when an instance of outer exists. Check to see if this is what you really want.

回答2:

Nested class are like(in sense ) Property of a class.

1. As in case of instance variable it only when available when its object is created as same as inner class also available when outer's object will created.

So if you want to extend this then make your inner class as static inner class
As jordao suggest above

回答3:

Try this, (Read nested class inheritance rules).

abstract class normal1 extends something { }

class outer
{
  abstract class  inner extends normal1{}
}

class Outer1 extends outer
{
  class General extends inner {}
}

回答4:

In your class General modify its constructor a to call super inner class constructor. here is the code..

public General(){
    new outer().super();
}

来源：https://stackoverflow.com/questions/8177725/no-enclosing-instance-of-type-perfhelper-is-available-due-to-some-intermediate-c