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From "Shapira, Yoav" <Yoav.Shap...@mpi.com>
Subject RE: instance of (ot)
Date Thu, 20 Feb 2003 19:35:31 GMT

Howdy,

>  The problem is that I want to test if an object is subclass of a
>java.lang.Class INSTANCE... Nonsense example:

Maybe I'm still not understanding ;)  But why doesn't the instanceof
operator work for you?

Your example:
>  java.util.Date date1 = new java.util.Date();
>  java.sql.Date date2 = new java.sql.Date();
>  Class clasz = date1.getClass();
>  if (date2 instanceof clasz)
>  {
>      do something...
>  }

Why not just do
if(date2 instanceof date1) ...
rather than if(date2 instanceof date1.getClass()) ??

Or are you looking for a comparison that doesn't make subclasses equal?
For example:

Set h1 = new LinkedHashSet();
if(h1 instanceof LinkedHashSet) {
  // This is true
}

if(h1 instanceof HashSet) {
  // This is true
}

if(h1 instanceof Set) { 
  // This is true
}

But you only want the first one?  How about

Object obj1 = new Object1();
Object obj2 = new Object2(); // Object2 extends Object1

if(obj1 instanceof obj1) {
  // This is false
}

if(obj2 instanceof ob1) {
  // This is true
}

if(obj2.getClass().getName().equals(obj1.getClass().getName()) {
 // This is false -- is this what you want?
}

Yoav Shapira
Millennium ChemInformatics



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