如何在RecyclerView中使用光标适配器制作一张以上的卡？

Question

I'm using a grid layout in RecyclerView in which each card displays some information from an SQLite Database using cursor adapter and cursor loader. I've used a library for achieving this.

The problem is all the cards are not getting displayed. When I run the app for the first time, only one card is displayed which shows data from the last row of the database. But I want it to show data from the first row. If I close and run the app again, two cards are displayed but both cards have same data, that is from the last row of the database again. I want the second card to display data from second row. The third time, three cards are displayed and the pattern continues.

Please help me to display the exact required number of cards each time that takes data from the corresponding row in the database.

MainActivity.java

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Cursor>  {

    private RecyclerView recyclerView;
    private RecyclerViewAdapter adapter;

    ContentResolver contentResolver;

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

        contentResolver = getContentResolver();

        insertRecipes();

        recyclerView = (RecyclerView) findViewById(R.id.recycler_view);

        adapter = new RecyclerViewAdapter(getBaseContext());

        Log.v("MainActivity", "instantiating adapter");

        recyclerView.setAdapter(adapter);

        Log.v("MainActivity", "setting adapter");

        recyclerView.setLayoutManager(new GridLayoutManager(getBaseContext(), 2));

        Log.v("MainActivity", "setting layout manager for recycler view");

        getSupportLoaderManager().initLoader(0, null, this);
    }

    @Override
    protected void onStart() {
        super.onStart();
    }


    private void insertRecipes()
    {
        ContentValues values = new ContentValues();
        values.put(AppytizerEntry.COLUMN_APPYTIZER_NAME, "test name 1");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_INGREDIENTS, "chips, salt, pepper");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_DIRECTIONS, "mix chips, salt and pepper. eat it");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TOFDISH, AppytizerEntry.TOFDISH_VEGETARIAN);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_COURSE, AppytizerEntry.COURSE_SNACKS);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TIME, 2);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_CALORIES, 100);
        //values.put(AppytizerEntry.COLUMN_APPYTIZER_IMAGE, );

        values.put(AppytizerEntry.COLUMN_APPYTIZER_NAME, "test name 2");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_INGREDIENTS, "chips, salt, pepper");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_DIRECTIONS, "mix chips, salt and pepper. eat it");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TOFDISH, AppytizerEntry.TOFDISH_VEGETARIAN);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_COURSE, AppytizerEntry.COURSE_SNACKS);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TIME, 2);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_CALORIES, 100);
        //values.put(AppytizerEntry.COLUMN_APPYTIZER_IMAGE, );

        values.put(AppytizerEntry.COLUMN_APPYTIZER_NAME, "test name 3");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_INGREDIENTS, "chips, salt, pepper");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_DIRECTIONS, "mix chips, salt and pepper. eat it");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TOFDISH, AppytizerEntry.TOFDISH_VEGETARIAN);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_COURSE, AppytizerEntry.COURSE_SNACKS);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TIME, 2);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_CALORIES, 100);
        //values.put(AppytizerEntry.COLUMN_APPYTIZER_IMAGE, );

        values.put(AppytizerEntry.COLUMN_APPYTIZER_NAME, "test name 4");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_INGREDIENTS, "chips, salt, pepper");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_DIRECTIONS, "mix chips, salt and pepper. eat it");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TOFDISH, AppytizerEntry.TOFDISH_VEGETARIAN);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_COURSE, AppytizerEntry.COURSE_SNACKS);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TIME, 2);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_CALORIES, 100);
        //values.put(AppytizerEntry.COLUMN_APPYTIZER_IMAGE, );

        values.put(AppytizerEntry.COLUMN_APPYTIZER_NAME, "test name 5");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_INGREDIENTS, "chips, salt, pepper");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_DIRECTIONS, "mix chips, salt and pepper. eat it");
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TOFDISH, AppytizerEntry.TOFDISH_VEGETARIAN);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_COURSE, AppytizerEntry.COURSE_SNACKS);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_TIME, 2);
        values.put(AppytizerEntry.COLUMN_APPYTIZER_CALORIES, 100);
        //values.put(AppytizerEntry.COLUMN_APPYTIZER_IMAGE, );

        Uri returnedUri = contentResolver.insert(AppytizerEntry.CONTENT_URI, values);

    }

    @Override
    public Loader<Cursor> onCreateLoader(int id, Bundle args) {

        String[] projection = {
                AppytizerEntry._ID,
                AppytizerEntry.COLUMN_APPYTIZER_NAME
        };

        Uri CONTENT_URI = AppytizerEntry.CONTENT_URI;
        CursorLoader cursorLoader = new CursorLoader(this, CONTENT_URI, projection, null, null, null);

        return cursorLoader;

    }

    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        adapter.swapCursor(data);
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        adapter.swapCursor(null);
    }
}

RecyclerViewAdapter.java

public class RecyclerViewAdapter extends RecyclerViewCursorAdapter<RecyclerViewAdapter.MyViewHolder> {

public RecyclerViewAdapter(Context context)
{
    super(context);

    setupCursorAdapter(null, 0, R.layout.custom_row, false);

    Log.v("Adapter", "RecyclerViewAdapter constructor");
}


@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    Log.v("Adapter", "onCreateViewHolder");
    return new MyViewHolder(mCursorAdapter.newView(mContext, mCursorAdapter.getCursor(), parent));
}

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {

    Log.v("Adapter", "onBindViewHolder");

    mCursorAdapter.getCursor().moveToFirst();

    Log.v("Adapter", "moving to position " + position);

    setViewHolder(holder);
    mCursorAdapter.bindView(null, mContext, mCursorAdapter.getCursor());        
}

public class MyViewHolder extends RecyclerViewCursorViewHolder {

    public final TextView title;

    public MyViewHolder(View view)
    {
        super(view);

        Log.v("Adapter", "MyViewHolder constructor");

        title = (TextView) view.findViewById(R.id.title);
    }

    int i = 0;

    @Override
    public void bindCursor(Cursor cursor) {
        int titleColumnIndex = cursor.getColumnIndex(AppytizerContract.AppytizerEntry.COLUMN_APPYTIZER_NAME);

        title.setText(cursor.getString(titleColumnIndex));

        if(i<4)
        {
            cursor.moveToNext();
            i++;
        }

        Log.v("Adapter", "bindCursor");
    }
}

}

Answer 1

I am not very familiar with ContentValues, but shouldn't you have an database.insert(TABLE_NAME, null, contentValues); between each test record?

Code example for ContentValues

That would explain that you see only the last record the first time, and a duplication the second time you run the app.

Answer 2

更好的方法是使用ContentResolver.bulkInsert。