dagger simple example gives IllegalStateException

Question

I'm experimenting with Dagger. Now I don't fully understand how everything works. So I wrote a test project.

This is my MainActivity:

public class MainActivity extends Activity {
    private ObjectGraph mActivityGraph;
    @Inject Vehicle car;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mActivityGraph = ObjectGraph.create(new ActivityModule());
        mActivityGraph.validate();
        mActivityGraph.inject(this);
    }
}

This is my ActivityModule:

@Module(
        injects =
                {
                        Vehicle.class,
                        MainActivity.class,
                        Wheels.class
                }
)
public class ActivityModule extends Application{

    @Provides Wheels provideWheels()
    {
        return new Wheels(4,"X12");
    }
}

In my manifest I added the ActivityModule as name at the application.

This is my Vehicle class:

@Module(
        includes = Wheels.class
)
public class Vehicle {
    @Inject
    Wheels wheels;
    private String type;

    public Vehicle(String type) {
        this.type = type;
    }
}

and this is my wheels:

public class Wheels {
    private int inch;
    private String brand;

    @Inject
    public Wheels(int inch, String brand) {
        this.inch = inch;
        this.brand = brand;
    }
}

Now what I want to accomplish is that I have a car in MainActivity that injects his wheels. Now I don't know how to create my car in the mainActivity because I want to create a car with a parameter as String on what the user fills in.

I get this:

Error:(8, 8) error: Graph validation failed: No @Module on edu.ida.daggertest.app.Wheels
Error:(20, 8) error: Unknown error java.lang.IllegalStateException thrown by javac in graph validation: Unable to create binding for edu.ida.daggertest.app.Vehicle

Answer 1

I found the problem. This is my edited code. The problem was the creation off the graph.

public class MainActivity extends Activity {
    final static String TAG = MainActivity.class.getName();
    private ObjectGraph mActivityGraph;
    @Inject
    Vehicle car;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mActivityGraph = ObjectGraph.create(new ActivityModule());
        mActivityGraph.inject(this);

       Log.d(TAG,String.valueOf(car.getWheels().getInch()));
       Log.d(TAG,car.getWheels().getBrand());
    }
}


@Module(
        injects =
                {
                        Vehicle.class,
                        MainActivity.class,
                        Wheels.class
                },
        complete = false
)
public class ActivityModule{

    @Provides Wheels provideWheels()
    {
        return new Wheels(4,"X12");
    }
}

public class Vehicle {

    @Inject
    Wheels wheels;
    private String type;

    public String getType() {
        return type;
    }

    public Wheels getWheels() {
        return wheels;
    }
}

public class Wheels {
    private int inch;
    private String brand;

    @Inject
    public Wheels(int inch, String brand) {
        this.inch = inch;
        this.brand = brand;
    }

    public int getInch() {
        return inch;
    }

    public String getBrand() {
        return brand;
    }
}

The completes false is required otherwise dagger is going to complain about injectable constructors Integer and String.

Answer 2

@Module(
        includes = Wheels.class
)
public class Vehicle {

Actually this caused your compile-time error, because Wheels is not a module