Hilt - Field injection returning a null object refernece

Question

This is my first time using Hilt for DI and I'm unsure what I'm doing incorrectly. I'm trying to Field inject my TestClass into my MainActivity, but it's giving me a null object reference when I call the method of the injected TestClass

I've made sure to create an BaseApplication class that has the annotation HiltAndroidApp

@HiltAndroidApp
public class BaseApplication extends Application {
  ...
}

The class I'm trying to inject into my MainActivity

import javax.inject.Inject;

public class TestClass {

    @Inject
    public TestClass() {
    }

    public String getName(){
        return "Hello World";
    }
}

And using FieldInjection in my MainActivity:

@AndroidEntryPoint
public class MainActivity extends AppCompatActivity implements TestAdapterCallback {

    @Inject
    TestClass testClass;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);

        Timber.d(testClass.getName()); //Giving a null object reference
    
        ...

I followed a tutorial off youtube that is doing Field Injection. Not sure what I'm doing incorrectly here.

I'm stupid and only added ```implementation 'com.google.dagger:hilt-android:2.37'``` . I needed to also add ```annotationProcessor 'com.google.dagger:hilt-compiler:2.37'```, ```classpath 'com.google.dagger:hilt-android-gradle-plugin:2.37'```, and ```apply plugin: 'dagger.hilt.android.plugin'```. — DIRTY DAVE, Jun 28 '21 at 02:06
I'm glad you've solved your problem! When you get a chance, please copy your comment into the answer box as a [self-answer](https://stackoverflow.com/help/self-answer) (aside from the "I'm stupid"; you're not) and accept it a couple of days later. That marks your problem as solved, allows others to find and upvote it, and allows future readers to edit or update your answer. — Jeff Bowman, Jul 01 '21 at 20:26

score 3 · Accepted Answer · answered Jul 01 '21 at 23:47

I only added implementation 'com.google.dagger:hilt-android:2.37' in my dependencies when I needed to also add

apply plugin: 'com.android.application'
apply plugin: 'dagger.hilt.android.plugin'

...

dependencies {
    implementation 'com.google.dagger:hilt-android:2.37
    annotationProcessor 'com.google.dagger:hilt-compiler:2.37'
}

buildscript {
    repositories {
        google()
        jcenter()
        
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.3'

        classpath 'com.google.dagger:hilt-android-gradle-plugin:2.37'
    }
}

Hilt - Field injection returning a null object refernece

1 Answers1