playframework : NullpointerException when startup

Question

I'm using Play 1.2.7, somehow I found my project become weird, when I start the application, and visit any valid URL, it shows an NullPointerException :

Oops: NullPointerException
An unexpected error occured caused by exception NullPointerException: null

play.exceptions.UnexpectedException: Unexpected Error
    at play.Play.start(Play.java:563)
    at play.Play.detectChanges(Play.java:637)
    at play.Invoker$Invocation.init(Invoker.java:198)
    at Invocation.HTTP Request(Play!)
Caused by: java.lang.NullPointerException
    at play.classloading.ApplicationCompiler$2.acceptResult(ApplicationCompiler.java:266)
    at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:478)
    at play.classloading.ApplicationCompiler.compile(ApplicationCompiler.java:282)
    at play.classloading.ApplicationClassloader.getAllClasses(ApplicationClassloader.java:426)
    at play.Play.start(Play.java:523)
    ... 3 more

And then I try to refresh the page, 2 or 3 time later, it become normal. What's going on here?

Answer 1

play doesn't support the following format in one class

public class A{

------

}

class B{

--

}

so make two different class instead of putting both in single class or use nested class.

Answer 2

It is a known bug: http://play.lighthouseapp.com/projects/57987/tickets/1379-unexpectedexception .

Maybe you use nested classes and Play has problems with it.