Java cloning abstract objects

Question

I\'m wondering if there is any way to do the following. I have an abstract class, Shape, and all its different subclasses and I want to override the clone metho

Answer 1

You can resolve with reflection:

public abstract class Shape {

    private String str;

    public Shape()  {

    }

    protected Shape(String str) {
        this.str = str;
    }

    public Shape clone() throws CloneNotSupportedException
    {
        try {
            return (Shape)getClass().getDeclaredConstructor(String.class).newInstance(this.toString());
        } catch (Exception e) {
            throw new CloneNotSupportedException();
        }
    }

    public String toString() {
        return "shape";
    }

public class Round extends Shape
{
    public Round()
    {
        super();
    }
    protected Round(String str) {
        super(str);
    }

    @Override
    public String toString() {
        return "round";
    }
}

main(){
  Shape round = new Round();        
  Shape clone = round.clone();
  System.out.println(round);
  System.out.println(clone);
}

but - IMO - is a poor implementation and error-prone with a lot of pits; the best use of Cloneable and Object.clone() is to not use them! You have a lot of way to do the same thing (like serialization for deep-clone) and shallow-clone that allow your a better control of flow.