Basic AndroidApplication class

AppComponent.java

@Singleton @Component(modules = AppModule.class) public interface AppComponent {
    void inject(MainActivity activity);
}

AppModule.java

/**
 * A module for Android-specific dependencies which require a {@link Context} or
 * {@link android.app.Application} to create.
 */
@Module public class AppModule {
    private final DevStatApplication application;

    public AppModule(DevStatApplication application) {
        this.application = application;
    }

    /**
     * Allow the application context to be injected but require that it be annotated with
     * {@link ApplicationContext @Annotation} to explicitly differentiate it from an activity context.
     */
    @Provides @Singleton @ApplicationContext Context provideContext() {
        return application;
    }

    // @Provides @Singleton StatHelper provideStatHelper() {
    //     return new StatHelper(application);
    // }

    @Qualifier @Documented @Retention(RetentionPolicy.RUNTIME) public @interface ApplicationContext {
    }
}

BaseApplication.java

public class BaseApplication extends Application {

    private static final String TAG = BaseApplication.class.getSimpleName();
    
    private AppComponent component;

    @Override public void onCreate() {
        super.onCreate();
        
        Fabric.with(this, new Crashlytics());
        LeakCanary.install(this);
        
        component = DaggerAppComponent.builder()
                .appModule(new AppModule(this))
                .build();

        if (BuildConfig.DEBUG) {
            Stetho.initializeWithDefaults(this);
            registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
                @Override public void onActivityCreated(Activity activity, Bundle bundle) {
                    Log.d(TAG, activity.getLocalClassName() + " created. Intent extras: " + getJSONFromBundle(activity.getIntent().getExtras()));
                }

                @Override public void onActivityStarted(Activity activity) { }

                @Override public void onActivityResumed(Activity activity) { }

                @Override public void onActivityPaused(Activity activity) { }

                @Override public void onActivityStopped(Activity activity) { }

                @Override public void onActivitySaveInstanceState(Activity activity, Bundle bundle) { }

                @Override public void onActivityDestroyed(Activity activity) { }
            });
        }
    }

    public static String getJSONFromBundle(Bundle bundle) {
        if (bundle == null || Build.VERSION.SDK_INT <= Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) {
            return null;
        }
        JSONObject json = new JSONObject();
        Set<String> keys = bundle.keySet();
        for (String key : keys) {
            try {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                    json.put(key, JSONObject.wrap(bundle.get(key)));
                }
            } catch(JSONException ignore) { }
        }
        return json.toString();
    }
    
    public AppComponent component() {
        return component;
    }
}

build.gradle

// Top level gradle:
buildscript {
  repositories {
    maven { url 'https://maven.fabric.io/public' }
    jcenter()
  }
  dependencies {
    classpath 'io.fabric.tools:gradle:1.20.1'
    classpath 'com.neenbedankt.gradle.plugins:android-apt:1.8'

  }
}


apply plugin: 'io.fabric'
apply plugin: 'com.neenbedankt.android-apt'

repositories {
    maven { url 'https://maven.fabric.io/public' }
}

dependencies {
    debugCompile 'com.squareup.leakcanary:leakcanary-android:1.3.1'
    releaseCompile 'com.squareup.leakcanary:leakcanary-android-no-op:1.3.1'
    
    // Crashlytics
    compile('com.crashlytics.sdk.android:crashlytics:2.5.1@aar') {
        transitive = true;
    }
    
    // OkHTTP
    compile 'com.squareup.okhttp:okhttp:2.5.0'
    
      // Stetho
    compile 'com.facebook.stetho:stetho:1.2.0'
    compile 'com.facebook.stetho:stetho-okhttp:1.3.1'
    
    // Dagger
    provided 'javax.annotation:jsr250-api:1.0'
    compile 'com.google.dagger:dagger:2.0.2'
    apt 'com.google.dagger:dagger-compiler:2.0.1'
}

RestClient.java

// Inside init
client = new OkHttpClient();
if (BuildConfig.DEBUG) {
    client.networkInterceptors().add(new StethoInterceptor());
}