I am trying to check if a Java String is not null, not empty and not whitespace.
null
In my mind, this code should have been quite up for the job.
You could take a look at JSR 303 Bean Validtion wich contains the Annotatinos @NotEmpty and @NotNull. Bean Validation is cool because you can seperate validation issues from the original intend of the method.
@NotEmpty
@NotNull