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dddenis
Asked: 2020-08-18 00:44:24 +0800 CST 2020-08-18 00:44:24 +0800 CST

Is it possible to create a class constant when inheriting in Java?

  • 772

I have a class that is abstract with a couple of abstract methods and I need all the classes that inherit from it to have a final static String field which contains the 'simple' name of the child class, called TAG. I have been trying several ways, but they all prevent me from compiling.

Is this possible to do? And if so, how is it done?

So it works for me, but I don't want it done as a field of the instance.

abstract class A{

    protected final String TAG;

    public A() {
        TAG = getClass().getSimpleName();
    }
}

I want to get the TAG from the child class as if it were from the class, not from the instance, like this:

class B extends A {
    public void mostrar() {
        System.out.println(B.TAG);
    }
}
java

2 Answers

  1. Best Answer

    To your question, YES , it is possible to have a dynamic constant as you need, here you can see a discussion (in English)

    Answered this, in my opinion, I think you don't need a constant for your purpose, basically because you will complicate your life since you have an abstract class, a final constant and inherited classes...

    I propose 2 alternatives (see how I get it getSimpleName()in both cases if you want to make variations)

    Method 1 (inheriting, with method, not statically)

    public abstract class Q {
    public void mostrar() {
        System.out.println(this.getClass().getSimpleName());
    }
}

    Let's take 2 example classes:

    public class SubQ extends Q {
}

    public class OtraQ extends Q {
}

    And a main:

    public static void main(String[] args) {
    SubQ sq = new SubQ();
    sq.mostrar();
    
    OtraQ oq = new OtraQ();
    oq.mostrar();
}

    EXIT:

    SubQ
OtraQ

    Method 2 (inheriting, without method, statically)

    Having a class structure like yours, without method or constant you can directly have the data you want like this:

    System.out.println(Q.class.getSimpleName());
System.out.println(SubQ.class.getSimpleName());
System.out.println(OtraQ.class.getSimpleName());

    EXIT:

    Q
SubQ
OtraQ
    • 3

  2. The way to do what you want can be through inheritance, creating a method which gets the name of the class:

    abstract class ClassA{


    public void mostrar() {
        System.out.println("Simple name: " + getClass().getSimpleName());
    }
}

class ClassB extends ClassA {

}

class ClassX extends ClassA {

}


public class myApplication {

    public static void main(String[] args) {
        ClassB b = new ClassB();
        b.mostrar();     
        ClassX x = new ClassX();
        x.mostrar();   
    }

}

    Having as output:

    Simple name: ClassB
Simple name: ClassX
    • -1