Name: nt126004 Date: 09/09/2002


FULL PRODUCT VERSION :
java version "1.4.1-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-rc-b19)
Java HotSpot(TM) Client VM (build 1.4.1-rc-b19, mixed mode)

FULL OPERATING SYSTEM VERSION : Windows 2000, SP3


A DESCRIPTION OF THE PROBLEM :

In the java.text.MessageFormat class there is a version of
format() with this signature:

format(Object arguments, StringBuffer result, FieldPosition
pos) // form 1

There is also a second format() method with a very similar
signature:

format(Object[] arguments, StringBuffer result,
FieldPosition pos) // form 2


If you look at the source code for "Form 1" you will see that it is *logically impossible* to call this method successfully. Whoever wrote the MessageFormat class made a mistake in writing this method.

The first format() method has a single statement in its
body (again, look at the source code if you like):

return subformat((Object[]) arguments, result, pos, null);

The return statement will *NEVER, EVER, EVER* be executed --
 it is 100% impossible. It tries to cast the 'arguments' parameter to an Object[]. Well that's fine except that form 2 of the format() method (shown above) *already uses* a Object[] as its first parameter. If a client of this method passes an Object[] as the first argument it is the second form of the format() method that gets called -- the one that takes an Object[] parameter -- not the first form.

The only time the first form gets called is when a non- array Object is passed. But then the method tries to cast that Object to an Object[] and boom! ClassCastException!

I originally submitted this bug 1.5 years ago. It was given a review ID of 4407453. The reviewer said it was a duplicate of 4228682, which I agree with. The evaluator's assessment of 4228682 is sloppy, I think. I don't think the
reviewer understood that the first form of format() will never execute correctly.

The first form of format() is essentially non-functioning at this point -- it's 100% brain dead.

A simple fix is all that's need though -- change the method's implementation to:

return subformat(new Object[] {arguments}, result, pos, null);

Please look at this carefully. It's important to understand that the existing implementation of the first format() method does absolutely nothing -- except throw ClassCastExceptions. Currently, it does not call subformat().



REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.text.*;

public class Tester {
  public static void main(String[] args) {
    MessageFormat mf = new MessageFormat("Hi {0}, nice to see you.");

    String result1 = mf.format("Skippy"); // ClassCastException!!
    String result2 = mf.format(new String[] {"Skippy"}); // A-OK!!
  }
}

---------- END SOURCE ----------

CUSTOMER WORKAROUND :
When you call format(), make sure the Object parameter is
really an Object[].
(Review ID: 163722)
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