Re: Construct a superclass as itself

The87Boy wrote:


First, I feel obliged to point out that this technically does what you
wrote in you first example.

    public static void main( String[] args )
    {
       Parent parent = new Parent();
       Parent parent2 = parent;
    }

Just in case that's actually what you need. If you need to go with
cloning, here's a template you can use. Not the best example, perhaps,
but I think it's largely self-explanatory. Note that you MUST call
super.clone() for the clone() method to work correctly, because this
class is not final. Note also that final fields can be used, they just
can't be changed.

public class Parent implements Cloneable {

    int a = 42;
    final int b=0;
    final long c=0;
    int d;

    public static Parent madeFrom( Parent p ) {
       Parent copy;
       try {
          copy = p.clone();
       } catch( CloneNotSupportedException ex ) {
          throw new AssertionError(); // can't happen
       }
       copy.a = 42; // init to default value again
// copy.b = 0; // Oops
       return copy;
    }

    @Override
    protected Parent clone()
            throws CloneNotSupportedException
    {
       Parent clone = (Parent) super.clone();
// clone.c = 0; // Oops.
       clone.d = 0;
       return clone;
    }

}