In-depth understanding of member variables in Child class inherited from parent class

 

The tests are summarized as follows:

Member variables in inheritance:

First run the Code:

Public class Testextends {
Int a = 0;
Public static void main (String [] args ){
Sub s = new Sub ();
System. out. println (s. );
System. out. println (Testextends) s). );
}
}


Class Sub extends Testextends {
Int a = 1;
}

Print result:

1
0

 

Cause: because a is defined in the parent class, a in Sub is not the same variable as a in Testextends.

So when printing s. a, it will print 1. After the conversion, it prints a in the parent class, that is, 0.

 

Traditionally, subclass inherits the parent class and shares a with the parent class. The premise is that the subclass does not define variables with the same name as the parent class. Demo:

 

Class Sub extends Testextends {
// Public final static String foo = "ball ";
Public Sub (){
A = 1;
}
}

The output is.

Excerpted from: wandering Xiao Qi's column