java – Performing an upcast from a derived to a base class, the method was not overridden

Question:

Did you override the method after performing an upward conversion from a derived class to a base class? Why didn't the nasvai() method of the base class get called?

class BasicClass {
    void nasvai() { System.out.println("Basic_Nasvai"); }
}

class SubBasic extends BasicClass {
    @Override
    void nasvai() { System.out.println("Nasvai"); }
}

class P231Exc20 {
    public static void main (String[] args) {
            SubBasic sb = new SubBasic();
            sb.nasvai();
            BasicClass bc = sb;
            bc.nasvai();
    }
}

Conclusion:

Nasvai
Nasvai

Answer:

And he shouldn't have changed. In Java (unlike C++, for example), all functions are made virtual (virtual) and to find the function to be called, a special table (VMT) is used, which (simplified) assigns each object, when created, its type (by constructor ). And proceeding from type causes the necessary function. When converting a type, a record is saved in the VMT and, accordingly, the function is called based on the type of the created object and not on the variable associated with it.