Basic concepts of inheritance (1)

One, the limitation of inheritance:

1,) A subclass cannot have more than one parent class, but can inherit multiple layers. In other words, the parent class can also have a parent class.

2) subclasses cannot access private members in the parent class. However, you can call a non-private method in the parent class, but you cannot call a private member directly in the parent class.

For example, the following is a false call to a private member in the parent class

classperson{//defining the Person class    PrivateString name;//define the Name property    Private intAge;//defining The Age property     Public voidsetName (String name) { This. Name =name; }     Public voidSetage (intAge ) {         This. Age =Age ; }     PublicString GetName () {return  This. Name; }     Public intGetage () {return  This. Age; }};classStudentextendsperson{//defining the Student class     Public voidFun () {System.out.println ("The name attribute in the parent class:" +name) ;//error, unable to accessSYSTEM.OUT.PRINTLN ("Age attribute in parent class:" + Age) ;//error, unable to access    }};

However, you can call private member variables indirectly by calling a non-private method in the parent class

classperson{//defining the Person class    PrivateString name;//define the Name property    PrivateintAge;//defining The Age property     Public voidsetName (String name) { This. Name =name; }     Public voidSetage (intAge ) {         This. Age =Age ; }     PublicString GetName () {return  This. Name; }     Public intGetage () {return  This. Age; }};classStudentextendsperson{//defining the Student class     Public voidFun () {System.out.println ("The name attribute in the parent class:" +GetName ()) ;//correct, indirect accessSYSTEM.OUT.PRINTLN ("Age attribute in parent class:" +getage ()) ;//correct, indirect access    }};

Basic concepts of inheritance (1)