Should @NotNull or should @NotEmpty be used for strings that you want to make sure the user enters a value for?

Is either the same as saying @Length(min=1)?

With all the validation annotations, I know you can have them on the entity class. However, I tried putting them on the getter methods on the session bean interfaces (for methods on the bean that are bound to form fields), but it doesn't seem to do anything.

Can you have these annotations on the session bean at all? (I imagine it would be possible because that's where you'd want to validate what the user is entering, right?)

Thanks.