Public: Anywhere in the app can be accessed anywhere; private: You can only access in the internal class of this class or this class; Friendly: The default to this scope when the keyword ID is identified, which indicates that you can access within the same package. If the parent class has a message
The domain method, the parent class, and subclasses are not in one package, in the subclass, the same cannot be accessed. Protected: If the parent class has the method of this scope, the subclass can access the method when the subclass inherits the parent class; if two classes are
In the package, one of the classes has a method of this scope, and the other class does not inherit the previous class, which is also not accessible to this method.
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