Class modifiers, member variable modifiers, method modifiers in Java

Class modifier:
Public common class, common, specified with the publicly modifier, visible to all classes.
Abstract class, there is no implementation method, the subclass is required to provide a method implementation.
Final (Non-inherited). Cannot be inherited by another class.
Friendly the default modifier (hidden declaration, nothing), only objects in the same package can use such a class.
Protected protected, visible to classes and all subclasses within the same package
Private, inner class, only within a class. It is mainly used to hide the implementation details of the class and to protect the data of the class.

Class modifiers, member variable modifiers, method modifiers in Java