Dagger 2 : Error While Getting A Multiple Instances Of Same Object With @named

How can i get multiple instances of same return type like cursor for example :- Module @CursorScope public class CursorModule { @Provides Cursor provideSongCursor(

Solution 1:

when you want to provide multiple variable of one type you must use @Named annotation like below:

Module@CursorScopepublicclassCursorModule {
@Provides@Named("songCursor")
CursorprovideSongCursor(@Named("Song") Musician musician) {
    return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
            newString[]{
                    BaseColumns._ID,
                    MediaStore.Audio.AudioColumns.TITLE,
                    MediaStore.Audio.AudioColumns.ARTIST,
                    MediaStore.Audio.AudioColumns.ALBUM,
                    MediaStore.Audio.AudioColumns.DURATION
            }, MediaStore.Audio.AudioColumns.IS_MUSIC + "=1", null, null);
}

@Provides@Named("albumCursor")
CursorprovideAlbumCursor(@Named("Album") Musician musician) {
    return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI,
            newString[]{
                    BaseColumns._ID,
                    MediaStore.Audio.AlbumColumns.ALBUM,
                    MediaStore.Audio.AlbumColumns.ARTIST,
                    MediaStore.Audio.AlbumColumns.NUMBER_OF_SONGS,
                    MediaStore.Audio.AlbumColumns.FIRST_YEAR
            }, null, null, null);
}
  @Provides@Named("artistCursor")
CursorprovideArtistCursor(@Named("Artist") Musician musician) {
    return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Artists.EXTERNAL_CONTENT_URI,
            newString[] {
                    BaseColumns._ID,
                    MediaStore.Audio.ArtistColumns.ARTIST,
                    MediaStore.Audio.ArtistColumns.NUMBER_OF_ALBUMS,
                    MediaStore.Audio.ArtistColumns.NUMBER_OF_TRACKS
            }, null, null,null);
}

@Provides@Named("genreCursor")
CursorprovideGenreCursor(@Named("Genres") Musician musician) {
    return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Genres.EXTERNAL_CONTENT_URI,
            newString[] {
                    BaseColumns._ID,
                    MediaStore.Audio.GenresColumns.NAME
            }, null, null, null);
}

@Provides@Named("playListCursor")
CursorprovidePlaylistCursor(@Named("Playlist") Musician musician) {
    return musician.getApplicationContext().getContentResolver().query(MediaStore.Audio.Playlists.EXTERNAL_CONTENT_URI,
            newString[] {
                    BaseColumns._ID,
                    MediaStore.Audio.PlaylistsColumns.NAME
            }, null, null, null);
}


}

then when you want to inject write like below:

@Inject@Named("soundCursor")
Cursor soundCursor;

@Inject@Named("albumCursor")
Cursor albumCursor;

@Inject@Named("artistCursor")
Cursor artistCursor;

@Inject@Named("genreCursor")
Cursor genreCursor;

@Inject@Named("playListCursor")
Cursor playListCursor;

if you wan to inject them in constructor injections do like below:

@Inject
public SomeClassConstructor(@Named("album") Cursor cursur)

and what you have written in your subcomponent interface I cant get it what it is, it must be like:

@CursorScope@Subcomponent(modules = CursorModule.class)
public interface CursorComponent {
   voidinject(TheClassThatWantsToUseInject1 obj);
   voidinject(TheClassThatWantsToUseInject2 obj);
}

and in your application component:

YourSubComponentInterface plus(CursorModule module);

Solution 2:

so finally I got the answer to my own question and it was the component part itself , you know software development is a so much of a hectic that too it becomes more of a burden when you quit cigerrates.

so all of the above was a simple approach and i made a different example with sharepreference, because my lappy crashed on archlinux.

so here are the snippet of the code i produced.

so the only thing i should have done is that i should have removed cursor injection params from the component interface.

none the less the snippet might help people.

Component :-

@Singleton@Component(modules = {MusicianModule.class, SharedPreferencesModule.class})
public interface MusicianComponent {
    voidinject(MainActivity mainActivity);
    Musicianmusician();
}

Module :-

@ModulepublicclassSharedPreferencesModule{

    @Provides@Named("default")
    SharedPreferences provideDefaultsharedPreferences(Musician musician) {
        return musician.getSharedPreferences("default", Context.MODE_PRIVATE);
    }

    @Provides@Named("secret")
    SharedPreferences provideSecretsharedPreferences(Musician musician) {
        return musician.getSharedPreferences("secret", Context.MODE_PRIVATE);
    }
}

Musician Module :-

@ModulepublicclassMusicianModule {

    privateMusician musician;

    publicMusicianModule(Musician musician) {
        this.musician = musician;
    }

    @Provides@SingletonMusicianprovidemusician() {
        return musician;
    }

    @Provides@SingletonApplicationprovideapplication(Musician musician) {
        return musician;
    }
}

Application class :-

publicclassMusicianextendsApplication {

    privateMusicianComponent musicianComponent;
    @OverridepublicvoidonCreate() {
        resolvedependency();
        super.onCreate();
    }


    privatevoidresolvedependency() {
        musicianComponent = DaggerMusicianComponent.builder()
                .musicianModule(newMusicianModule(this))
                .sharedPreferencesModule(newSharedPreferencesModule())
                .build();
    }


    publicstaticMusicianComponentgetMusicianComponent(Context context) {
        return ((Musician)context.getApplicationContext()).musicianComponent;
    }
}

And the injection in the MainActivity :-

publicclassMainActivityextendsAppCompatActivity {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentPagerAdapter} derivative, which will keep every
     * loaded fragment in memory. If this becomes too memory intensive, it
     * may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */private SectionsPagerAdapter mSectionsPagerAdapter;



    /**
     * The {@link ViewPager} that will host the section contents.
     */private ViewPager mViewPager;

    @Inject@Named("default")
    SharedPreferences defSharedPreferences;

    @Inject@Named("secret")
    SharedPreferences secSharedPreferences;

    @OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Musician.getMusicianComponent(this).inject(this);
        Toolbartoolbar= (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        // Create the adapter that will return a fragment for each of the three// primary sections of the activity.
        mSectionsPagerAdapter = newSectionsPagerAdapter(getSupportFragmentManager());
        defSharedPreferences.edit().putString("status", "worked").apply();
        secSharedPreferences.edit().putString("status", "worked").apply();

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);

        TabLayouttabLayout= (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);
    }


    @OverridepublicbooleanonCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        returntrue;
    }

    @OverridepublicbooleanonOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.intid= item.getItemId();

        //noinspection SimplifiableIfStatementif (id == R.id.action_settings) {
            returntrue;
        }

        returnsuper.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */publicstaticclassPlaceholderFragmentextendsFragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */privatestaticfinalStringARG_SECTION_NUMBER="section_number";

        publicPlaceholderFragment() {
        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */publicstatic PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragmentfragment=newPlaceholderFragment();
            Bundleargs=newBundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

        @Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            ViewrootView= inflater.inflate(R.layout.fragment_song, container, false);
            TextViewtextView= (TextView) rootView.findViewById(R.id.section_label);
            textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
            return rootView;
        }
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */publicclassSectionsPagerAdapterextendsFragmentPagerAdapter {

        publicSectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Overridepublic Fragment getItem(int position) {
            // getItem is called to instantiate the fragment for the given page.// Return a PlaceholderFragment (defined as a static inner class below).return PlaceholderFragment.newInstance(position + 1);
        }

        @OverridepublicintgetCount() {
            // Show 3 total pages.return3;
        }

        @Overridepublic CharSequence getPageTitle(int position) {
            switch (position) {
                case0:
                    return"SECTION 1";
                case1:
                    return"SECTION 2";
                case2:
                    return"SECTION 3";
            }
            returnnull;
        }
    }