Getting the name of a sub-class from within a super-class

Question

Let\'s say I have a base class named Entity. In that class, I have a static method to retrieve the class name:

class Entity {
    public static         


        

Answer 1

Not possible. Static methods are not runtime polymorphic in any way. It's absolutely impossible to distinguish these cases:

System.out.println(Entity.getClass());
System.out.println(User.getClass());

They compile to the same byte code (assuming that the method is defined in Entity).

Besides, how would you call this method in a way where it would make sense for it to be polymorphic?

Answer 2

This works for me

this.getClass().asSubclass(this.getClass())

But I'm not sure how it works though.

Answer 3

A static method is associated with a class, not with a specific object.

Consider how this would work if there were multiple subclasses -- e.g., Administrator is also an Entity. How would your static Entity method, associated only with the Entity class, know which subclass you wanted?

You could:

• Use the existing getClass() method.
• Pass an argument to your static getClass() method, and call an instance method on that object.
• Make your method non-static, and rename it.

Answer 4

If I understand your question correctly, I think the only way you can achieve what you want is to re-implement the static method in each subclass, for example:

class Entity {
    public static String getMyClass() {
        return Entity.class.getName();
    }
}

class Derived extends Entity {
    public static String getMyClass() {
        return Derived.class.getName();
    }
}

This will print package.Entity and package.Derived as you require. Messy but hey, if those are your constraints...

Answer 5

My context: superclass Entity with subclasses for XML objects. My solution: Create a class variable in the superclass

Class<?> claz;

Then in the subclass I would set the variable of the superclass in the constructor

public class SubClass {
   public SubClass() {
     claz = this.getClass();
   }
}

Answer 6

If i am taking it right you want to use your sub class in base class in static method I think you can do this by passing a class parameter to the method

class Entity {
    public static void useClass(Class c) {
        System.out.println(c);
        // to do code here
    }
}

class User extends Entity {
}

class main{
    public static void main(String[] args){
        Entity.useClass(Entity.class);
    }
}