Java – use generics to implement common methods in abstract classes

Suppose I have this hierarchy:

public abstract class AbstractEntity implements Cloneable {
    ...
    public AbstractEntity clone() {
        Cloner cloner = new Cloner();
        AbstractEntity cloned = cloner.deepClone(this);
        return cloned;
    }
}

public class EntityA extends AbstractEntity {
    ...
}

That's good. I can do this:

EntityA e1 = new EntityA();
EntityA e2 = (EntityA) e1.clone();

But I have to do a manual type conversion Is there any way to use Java generics to make the clone () method return the actual type of the subclass?

thank you!

Solution

I don't think we need generic drugs You can declare the clone () method in an abstract class and override it to return subclasses in subclasses

package inheritance;

public abstract class AbstractEntity {

    public abstract AbstractEntity clone();
}


package inheritance;

public class ClassA extends AbstractEntity {

    @Override
    public ClassA clone() { return null; }

}


package inheritance;

public class Driver {

    /**
     * @param args
     */
    public static void main(String[] args) {
        ClassA a = new ClassA();
        ClassA b = a.clone();
        System.out.println("all done");
    }

}

Isn't that what you want to do?