NullPointerException while trying to access @EJB bean in managed bean constructor

Question

I\'ve an EJB service.

@Stateless
public class SomeService {}

I\'d like to inject this in a viewscoped bean and initialize with it:

Answer 1

In other words, you're expecting that EJB injection works under the covers as follows:

ViewBean viewBean;
viewBean.someService = new SomeService(); // EJB injected, so that constructor can access it.
viewBean = new ViewBean(); // ViewBean constructed.

However, this is technically impossible. It's not possible to assign an instance variable when the instance isn't been constructed at all.

The canonical approach to perform a task based on injected dependencies directly after construction is to use a @PostConstruct annotated method.

So, to fix your concrete problem, just replace

public ViewBean() {

by

@PostConstruct
public void init() { // Note: Method name is fully free to your choice.

This way the process would under the covers be roughly as follows:

ViewBean viewBean;
viewBean = new ViewBean(); // ShiftBean constructed.
viewBean.someService = new SomeService(); // EJB injected.
viewBean.init(); // PostConstruct invoked.

Please note that the concrete problem has completely nothing to do with the view scope. You'd have had exactly the same problem when using a request, session or application scoped bean. This is thus another evidence that you have never actually excluded it from being the cause by testing using a different scope.