How I get the Context with guice in provider?

Question

How I get the Context? Am I doing something wrong here?

This is my Error in Android:

FATAL EXCEPTION: main com.google.inject.CreationException: Guice creation errors: 1) Error injecting constructor, java.lang.NullPointerException

public class DatabaseProvider implements Provider {

    @Inject
    protected static Provider<Context> contextProvider;
    //eror context is null
    protected Context context = contextProvider.get();

    @Override
    public DatabaseHelper get() {
        return (DatabaseHelper) OpenHelperManager
            .getHelper(context, DatabaseHelper.class);
    }
}

Implement DaoProvider:

public class DaoProvider<D extends Dao<E, ?>, E> implements Provider<D> {

@Inject
private DatabaseProvider databaseProvider;


private final Class<E> cls;

public DaoProvider(Class<E> cls) {
    this.cls = cls;
}

@Override
public D get() {

    try {
        return databaseProvider.get().getDao(cls);

    } catch (SQLException e) {
        Log.d("injection", "database provider error", e);
    }

    return null;
}

}

Implement in module:

public class BabyModule extends AbstractModule {
@Override
protected void configure() {

        TypeLiteral<Dao<Baby, Integer>> typeLiteral = new TypeLiteral<Dao<Baby,         Integer>>(){};
        DaoProvider<Dao<Baby,Integer>, Baby> provider = new DaoProvider<Dao<Baby,Integer>, Baby>(Baby.class);
        bind(typeLiteral).toProvider(provider);
}

}

Thanks for help

Any `@Inject` do not happen until _after_ the constructor was run. — Thorbjørn Ravn Andersen, Mar 16 '12 at 17:33
The object cannot be analysed for what to inject until _after_ it has been fully created. Hence the `contextProvider.get()` is being run before the contextProvder is set by Guice. — Thorbjørn Ravn Andersen, Mar 16 '12 at 18:10

score 2 · Accepted Answer · answered Mar 28 '12 at 07:00

I have my own solution. I get my context about the application.class now.

public class DatabaseHelperProvider implements Provider<DatabaseHelper> {

    @Inject
    Application application;

    @Override
    public DatabaseHelper get() {

    return OpenHelperManager
            .getHelper(application.getApplicationContext(), DatabaseHelper.class);
    }
}

score 1 · Answer 2 · answered Mar 28 '12 at 07:26

1

Simply using

@Inject Context context

instead of

@Inject protected static Provider<Context> contextProvider; //eror context is null protected Context context = contextProvider.get();

should solve your problem. If it doesn´t why you just don´t access the context lazy...

answered Mar 28 '12 at 07:26

onlythoughtworks

794
8
13

I had already tried. What do you mean? If it doesn´t why you just don´t access the context lazy... – user949884 Mar 28 '12 at 07:51

score -1 · Answer 3 · answered Mar 16 '12 at 11:39

-1

better:

@Override
public DatabaseHelper get(Context context) {
     return (DatabaseHelper) OpenHelperManager.getHelper(context, DatabaseHelper.class);
}

You can tak context from activity (Activity is extending Context).

answered Mar 16 '12 at 11:39

pjanecze

3,145
3
21
28

I call this in module to. About AbstractModule from guice. – user949884 Mar 16 '12 at 11:51
if you change the method signature, then it's not overriding the same method – emmby Mar 16 '12 at 19:19
So you have to get context in constructor - passing it as a parameter of constructor. – pjanecze Mar 17 '12 at 06:47

How I get the Context with guice in provider?

3 Answers3