@Inject fails to initialize object

Question

I am using tomee server to run my javaEE app. I have written a filter which injects an object. However the object does not seem to get instantiated :

Following is my code :

Filter.java

@Priority(value = 2)
@Provider
@Singleton
public class Filter implements ContainerRequestFilter {


     @Inject
     private Faculty faculty;


     public void filter(ContainerRequestContext requestContext) {
         System.out.println("faculty name is :"+faculty.getFacultyName());
     }
}

Faculty.java

import java.util.ArrayList;
import java.util.List;
import javax.annotation.PostConstruct;

public class Faculty {

    private List<String> facultyMembers;
    private String facultyName;

    @PostConstruct
    public void initialize() {
        this.facultyMembers = new ArrayList<String>();
        facultyMembers.add("Ian Schultz");
        facultyMembers.add("Diane Reyes");
        facultyName = "Computer Science";
    }

    public List<String> getFacultyMembers() {
        return facultyMembers;
    }

    public String getFacultyName() {
        return facultyName;
    }
}

I am getting an NPE. Following is the stack trace :

java.lang.NullPointerException
at com.xyz.commerceapp.filters.Filter.filter(TransactionStartFilter.java:45)
at org.apache.cxf.jaxrs.utils.JAXRSUtils.runContainerRequestFilters(JAXRSUtils.java:1645)
at org.apache.cxf.jaxrs.interceptor.JAXRSInInterceptor.processRequest(JAXRSInInterceptor.java:201)
at org.apache.cxf.jaxrs.interceptor.JAXRSInInterceptor.handleMessage(JAXRSInInterceptor.java:77)
at org.apache.cxf.phase.PhaseInterceptorChain.doIntercept(PhaseInterceptorChain.java:308)
at org.apache.cxf.transport.ChainInitiationObserver.onMessage(ChainInitiationObserver.java:121)

Here are the versions of the artifacts being used:

<openejb.version>5.0.0-SNAPSHOT</openejb.version>
<tomee.version>2.0.0-SNAPSHOT</tomee.version>

I have tried including the beans.xml in both META-INF and WEB-INF but I am still seeing the NPE.Can someone let me know what am I doing wrong ?

Why are you injecting directly to a class member, can't you do this by injecting *Faculty* to the constructor and then setting it there to the "faculty" field or am I missing something here? — Anupam Saini, Apr 05 '16 at 05:48
You must have wrongly used the import `javax.ejb.Singleton` instead of `javax.inject.Singleton`. — António Ribeiro, Apr 05 '16 at 07:37
The next TomEE version is 7.0.0, the 2.0.0 snapshots are very old. Please try against TomEE 7.0.0.M3. — John Ament, Apr 05 '16 at 11:29

score 1 · Accepted Answer · answered Apr 07 '16 at 16:34

1

The injection worked once I changed @Singleton to @ApplicationScoped.

answered Apr 07 '16 at 16:34

Suraj Menon

1,486
3
28
50

score 0 · Answer 2 · answered Apr 06 '16 at 03:29

0

Please see your imports , it should not be importing Priority from any other library. The correct one is this : import javax.annotation.Priority;

answered Apr 06 '16 at 03:29

arjun99

358
1
8

score -2 · Answer 3 · answered Apr 05 '16 at 05:47

-2

Make sure your archive (jar, war, …) has a beans.xml file defined

The beans.xml file is known as the bean archive descriptor. Below you can find the most simple example with just a root beans xml element:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://java.sun.com/xml/ns/javaee"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="
      http://java.sun.com/xml/ns/javaee 
      http://java.sun.com/xml/ns/javaee/beans_1_0.xsd">
</beans>

This file should be placed into META-INF/beans.xml or WEB-INF/beans.xml. If you don’t include this file in your module archive, CDI injection will not be active for this archive as the container will not scan the archive.

There are a few reasons why the spec was done this way:

Performance: The container only has to scan the modules where you’ve added the beans.xml
beans.xml also lets you define interceptors and decorators that have to be executed when the injection takes place.

Courtesy: Solving @Inject NullPointerException

answered Apr 05 '16 at 05:47

a3.14_Infinity

5,653
7
42
66

I had mentioned in the question: "I have tried including the beans.xml in both META-INF and WEB-INF but I am still seeing the NPE." – Suraj Menon Apr 05 '16 at 05:55
a stupid doubt may be: does your beans.xml have a bean referring to Faculty class? – a3.14_Infinity Apr 05 '16 at 06:40
It does not. I was under the impression that the annotations would take care of the wiring and that an empty bean.xml should suffice. – Suraj Menon Apr 05 '16 at 06:57
Could you try @Default annotation in Faculty class? Introduce @Default annotation over `public class Faculty` – a3.14_Infinity Apr 05 '16 at 07:34
Did not help. The NPE persisted. – Suraj Menon Apr 05 '16 at 08:21

@Inject fails to initialize object

3 Answers3