Mike`s Blog

Suppose you've got the following code:

if ((o1 instanceof Comparable)
 && (o2 instanceof Comparable))
{
   // Throws ClassCastException
   return ((Comparable) o1).compareTo((Comparable) o2);
}

Do you think compareTo() throws a ClassCastException?

Well, it does in the following case:
o1 is a javax.sql.Timestamp and o2 is a java.util.Date

Since Timestamp subclasses Date, this is a little bit confusing.

Update: I probably had an old installation of JRE (e.g. JRE < 1.5.0_06), as this bugs seems to be fixed in 1.5.0_07, see Sun Bug 5103041. This is fixed in the JRE I use at home 1.5.0_013. Thanks to my collegue Lars for pointing that out.

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