checkNotNull(participantForExperiment, new ParticipantForExperimentNotFoundException(participantId, experimentId));

Instead of using an IF condition to check whether participantForExperiment is null and then throw Exception, i want a one-liner in Guava like i mentioned above.

But i want to throw my own exception instead of NullPointerException if it is Null.

How can i do that in Guava?

For commonly used validation I’d be more inclined to use JSR 303 (Bean Validation) for which the reference implementation is Hibernate Validator 4. It uses similar annotations to OVal … e.g. @NotNull and is a standard so various web, persistence, etc. frameworks can help maintain your validation requirements.

Validation on method parameters (and return types) didn’t make it into that JSR, but there’s a pending JSR349 which is looking at adding it, and there’s an existing implementation in Hibernate Validator 4.2.

Perhaps the word requires is too strong. But IMO Validate.isTrue looks nicer than Preconditions.checkArgument because it reads more like a sentence in natural language. Just curious, why do you prefer not to use static imports?

I don’t understand your statement about Guava requires static import. I actually prefer not to use static import, and Preconditions.checkArgument works just fine.

The reason it’s better to include such a library goes beyond just the “Preconditions/Validate” stuff. There are many more tremendously useful things in Guava, and it’s a relatively small library. If you JUST want the argument check, then you’d probably be better off to write your own small utility class to handle that (or copy just Preconditions).

The big advantage for me with Guava in general, over Apache-Commons, is the support for generics, and the clean, precise APIs, without the proliferation of “what if” methods (already noted in several other comments), and how incredibly useful and powerful the Functions/Predicates/Collections stuff in there is.

Combine Guava, with Guice, and JSR-305 annotations (@Nullable, etc), and you have a great minimalist Java SE stack that doesn’t have to suck (Java isn’t dead yet!).