Re: Importing an object at runtime

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 30 Aug 2007 16:38:10 -0400

Message-ID:

<8dednX0akf8ut0rbnZ2dnUVZ_hqdnZ2d@comcast.com>

Manish Pandit wrote:

On Aug 30, 11:07 am, "Crouchez"
<b...@bllllllahblllbllahblahblahhh.com> wrote:

Class theClass = Class.forName("Object1");
Object1 o = theClass.newInstance();
((Object1)o).go();

I need to wrap the object as an Object1 to be able to call go(). If I am
reading the classes from disk and don't hardcode the classes into
Class.forName("????") how do I then wrap the resulting object?

Something like this:

  Class theClass = Class.forName(file);
  Object o = theClass.newInstance();
  ((obj.getClass().getName())o).go(); //can't do obj.getClass().getName()

How are you sure that "go()" is implemenented by the object you're
trying to instantiate? I believe this can be done in a cleaner way,
where you instantiate the object, and use instanceOf to make sure the
instance is implementing the interface which has "go()", cast it as
that interface (which is allowed) and then call the method go() on it.

Example:

  public interface Goer
  {
    public void go();
  }

  public class DoesGo implements Goer
  {
   public void go() { ... }
  }
....
  // inside some other method or class:

   Goer goer = new DoesGo();
  // can also instantiate with
  // Class<? extends Goer>.forName( "DoesGo" ).newInstance));

--
Lew