[JSR308] Nullness checker and generic checkNotNull function

Artemus Harper subanark at gmail.com
Tue Jan 20 12:23:15 EST 2009

This is mostly likely a problem with generics as they are currently  
not fully supported in the framework. There is a confusion between the  
annotations on the generic definition and those on its use (the  
framework is attempting to apply @Nullable and @NonNull to all T). You  
might be able to work around this by using multiple generic names.  
Although I don't have the current build on hand you could try:

public static <T,E extends T> @NonNull E checkNotNull(@Nullable T  
On Jan 19, 2009, at 10:16 AM, Piotr Zielinski wrote:

> Hi,
> I'm trying to implement a generic checkNotNull function along the  
> lines of
> public static <T> @NonNull T checkNotNull(@Nullable T object) {
>  if (object == null) {
>    throw new NullPointerException();
>  } else {
>    return object;
>  }
> }
> The intention is to provide a fail-fast gateway between annotated and
> non-annotated parts of my project code.  I've tried a few variants of
> the checkNonNull method signature: they either don't compile or still
> give nullability warning in expressions like (trivial)
> checkNotNull((Object) null).  Could you help?
> Thanks,
> Piotr
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