I have my own emulation of java.util.Timer (and quite a lot of other stuff missing in GWT). I have even a JUnit test proving it works in the browser.
I've just tried to convert some third-party library to GWT, which needed a Timer, and in some part of it, I call:
SystemUtils.getTimer().scheduleAtFixedRate(timerTask, value, value);
But the GWT compiler turns getTimer().scheduleAtFixedRate() to:
getTimer().nullMethod()
SystemUtils.getTimer() is a static method. I have googled for nullMethod(), but most hits are about:
null.nullMethod();
That doesn't apply to me. What could be going wrong, and what can I do to fix it?
[EDIT] Actually, the java.util.Timer emulation itself works, but it seems that (atm?) SystemUtils.getTimer() returns "undefined". Could that be the reason? Since getTimer() returns an instance created dynamically, how could the GWT compiler possibly make any assumption about the return value of getTimer(), and the presence/usage of the methods of the Timer type?
When I have seen this kind of errors it was caused by unreachable code: GWT had determined that some code was not reachable, turning off compilation for some stuff, but then it still somehow tried to link the unreachable code, showing this kind of errors.