Protected? int？ studentNum
Protected? String? Name;
Protected? String? Sex;
Protected? Double? Ji Cheng;
Public? Student ()? {
}
Public? Student (int? Number of students? String? Name,? String? Sex? Double? Ji Cheng)? {
this.studentNum？ =? studentNum
This name? =? Name;
This. Sex? =? Sex;
This. Chengji? =? Ji Cheng;
}
Abstract? Invalid? getPrint()；
}
//? Output students' names, student numbers, gender, grades and other parameters with polymorphic methods in Java.
Public? Class? StudentDemo？ Extension? Student? {
Public? StudentDemo()？ {}
Public? StudentDemo(int？ Number of students? String? Name,? String? Sex? Double? Ji Cheng)? {
Super (studentNum, name,? Sex? Ji Cheng);
}
Invalid? getPrint()？ {
System.out.println ("student number:"? +? super . student num)；
System.out.println ("Name:"？ +? super . name)；
System.out.println ("gender:"? +? super . sex)；
System.out.println ("grade:"？ +? super . chengji)；
}
Public? Static electricity Invalid? main(String[]？ args)？ {
//polymorphic instantiation
Student? s 1？ =? New? StudentDemo( 1, "Xiao Ming", "Male", 98.95);
//Output student information
s 1 . get print()；
system . out . println()；
//Convert to subclass type, that is, convert down.
Student? Student? =? (student) s1;
student . get print()； //output
}
}