Re-used event objects (was: Re: [kaffe] java.lang.reflect.Method virtual method call bug (CVS))

Benja Fallenstein b.fallenstein at
Sat Dec 28 15:30:18 PST 2002

Reading java/awt/, it seems like only events in the 
java.awt.Defaults.RecycleEvents bitmap should be re-used, but I can't 
see anything in the Kaffe source that would set RecycleEvents to 
anything but zero. What's going on?

- Benja

Benja Fallenstein wrote:

> Benja Fallenstein wrote:
>> Not completely; it starts up, but something in our call hierarchy 
>> eats simple key events like single characters, spaces or returns; 
>> more complex things like function keys, Tab or PgUp/PgDn are 
>> processed correctly. We do recieve the events, apparently, but 
>> something eats them. I haven't seen this on the proprietary JVMs, so 
>> I guess there must be some kind of incompatibility (trying to process 
>> key events across Javas is **icky**). I'll tell if I find out what's 
>> causing this.
> I have isolated the incompatibility: Kaffe re-uses KeyEvent objects; 
> after issuing a KEY_PRESSED event, it issues a KEY_TYPED event which 
> is the same object, with a field value changed inside. Interestingly, 
> the KEY_RELEASED events seem to be separate objects. Gzz implements 
> its own event queue to coordinate event processing with animation; 
> this is implemented by putting the KeyEvent objects in a LinkedList. 
> As it happens, Gzz by default only reacts to KEY_TYPED events, and as 
> it happens, all three KEY_* events are usually queued before any of 
> them is processed. This means that at the time we get around to 
> processing the key events, we have two KEY_TYPED and one KEY_RELEASED 
> event in the queue (because the original KEY_PRESSED event was changed 
> to KEY_TYPED by Kaffe).
> Gzz might be able to work around this, but I suggest that Kaffe not 
> re-use KeyEvent objects, as code like the above works fine on the 
> proprietary Javas and breaks on Kaffe in nonobvious ways. (Caching by 
> using weak references might be an option, but I wouldn't think it's 
> worth it...)
> - Benja

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