Why am I here will be an error?

CodePudding user response:

Your Boo class should not be put in SuperDemo class, should reflect encapsulation,

CodePudding user response:

Adds the static inner class want to direct the new modified
Or outside class. The inner class

CodePudding user response:

Ordinary class definition in each file can have only one, your AOO and BOO are defined in the same file, but also on the inside of another class,