Перетаскивание RecyclerView, которое заполняется из SQLiteDatabase

Информация:

У меня есть RecyclerView, и я заполняю его списком данных ArrayList внутри класса ListAdapter. Я получаю данные для dataList из таблицы SQLiteDatabase: TABLE_USERdETAIL в классе DbHelper. Я пытаюсь реализовать реорганизацию перетаскивания в RecyclerView с помощью класса SimpleItemTouchHelperCallback; однако, хотя теперь я могу перемещать элементы RecyclerView, список не сортируется и не сортируется; Я могу только временно перетаскивать элементы списка друг на друга, как показано на рисунке ниже, но это означает, что он будет постоянно помещать элементы списка в любое положение, которое он удерживал:

Я ожидаю, что проблема будет в классе ListAdapter, внутри метода onItemMove, но я не знаю, как решить мою проблему.

Вопрос: Как мне сделать эту функцию перетаскивания фактически реорганизовать список данных RecyclerView?

Обновление 5: Я обновил текущий код для дальнейшей помощи.

Класс ListAdapter

public class ListAdapter extends RecyclerView.Adapter<ListAdapter.ListViewHolder> {

    Context context;
    List<UserData> dataList = new ArrayList<>();
    LayoutInflater inflater;
    Listener listener;
    DbHelper dbHelper;



    public interface Listener {
        void nameToChnge(String name);
    }

    public ListAdapter(Context context, List<UserData> dataList1) {
        this.context = context;
        this.dataList = dataList1;
        //this.listener= (Listener) context;
        inflater = LayoutInflater.from(context);
    }


    @Override
    public ListViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View convertView = inflater.inflate(R.layout.recylerview_one, parent, false);
        ListViewHolder viewHolder = new ListViewHolder(convertView);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ListViewHolder holder, final int position) {
        holder.tv_name.setText(dataList.get(position).name);
        holder.tv_quantity.setText(dataList.get(position).quantity);
        holder.tv_description.setText(dataList.get(position).description + " ");

        if(dataList.get(position).description.isEmpty()) {
            holder.tv_description.setVisibility(View.GONE);
        }

        holder.relLayout.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                String s = dataList.get(position).id;
                Integer stringo = Integer.parseInt(s);
                Intent intent = new Intent(context, ItemEditActivity.class);
                intent.putExtra("ItemNumber", stringo);
                context.startActivity(intent);
            }
        });
    }

    @Override
    public int getItemCount() {
        return dataList.size();
    }

    class ListViewHolder extends RecyclerView.ViewHolder implements ItemTouchHelperViewHolder {
        TextView tv_name, tv_quantity, tv_description;
        RelativeLayout relLayout;

        public ListViewHolder(View itemView) {
            super(itemView);
            tv_name = (TextView) itemView.findViewById(R.id.nameDisplay);
            tv_quantity = (TextView) itemView.findViewById(R.id.quantityDisplay);
            tv_description = (TextView) itemView.findViewById(R.id.descriptionDisplay);
            relLayout = (RelativeLayout) itemView.findViewById(R.id.relLayout);
        }
        @Override
        public void onItemSelected() {
            Log.d("ListViewHolder", "item selected");
        }

        @Override
        public void onItemClear() {
            Log.d("ListViewHolder", "item clear");
            for (int count = 0; count < dataList.size(); count++) {
                UserData u = dataList.get(count);
                u.setSort(count);
                dbHelper.updateUserData(u);
            }
            notifyDataSetChanged();
        }
    }

    public void onItemDismiss(int position) {
        dataList.remove(position);
        //dbHelper = DbHelper.getInstance(context);
        //dbHelper.deleteRowItem(position + 1);
        notifyItemRemoved(position);
    }

    //Collections.swap(dataList, fromPosition, toPosition);
    //notifyItemMoved(fromPosition, toPosition);


    public boolean onItemMove(int fromPosition, int toPosition) {
        if (fromPosition < toPosition) {
            for (int i = fromPosition; i < toPosition; i++) {
                Collections.swap(dataList, i, i + 1);
            }
        } else {
            for (int i = fromPosition; i > toPosition; i--) {
                Collections.swap(dataList, i, i - 1);
            }
        }
        notifyItemMoved(fromPosition, toPosition);
        return true;
    }
}

Класс SimpleItemTouchHelperCallback

public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback {
    private final ListAdapter  mAdapter;


    public SimpleItemTouchHelperCallback(ListAdapter adapter) {
        mAdapter = adapter;
    }

    @Override
    public boolean isLongPressDragEnabled() {return true; }

    @Override
    public boolean isItemViewSwipeEnabled() { return false; }

    @Override
    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
        int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END;
        return makeMovementFlags(dragFlags, swipeFlags);
    }

    @Override
    public boolean onMove(RecyclerView recyclerView,
                          RecyclerView.ViewHolder viewHolder,
                          RecyclerView.ViewHolder target) {
        mAdapter.onItemMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
        return true;
    }

    @Override
    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
        mAdapter.onItemDismiss(viewHolder.getAdapterPosition());
    }

    @Override
    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
        // We only want the active item to change
        if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
            if (viewHolder instanceof ItemTouchHelperViewHolder) {
                // Let the view holder know that this item is being moved or dragged
                Log.i("ADAPTER", "----DRAGGING----");
                ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
                itemViewHolder.onItemSelected();
            }
        }

        super.onSelectedChanged(viewHolder, actionState);
    }
    @Override
    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        super.clearView(recyclerView, viewHolder);

        if (viewHolder instanceof ItemTouchHelperViewHolder) {
            // Tell the view holder it time to restore the idle state
            ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
            itemViewHolder.onItemClear();
        }
    }
}

Класс DbHelper

Открытый класс DbHelper расширяет SQLiteOpenHelper {

   private static final String DATABASE_NAME = "UserDatabase";
    private static final int DATABASE_VERSION = 2;
    private static DbHelper mDbHelper;

    public static String TABLE_USERdETAIL = "userdetail";

    private static final String _ID = "_id";
    private static final String SORT_ID = "sort_id";
    private static final String NAME = "name";
    private static final String QUANTITY = "quantity";
    private static final String WEIGHT = "weight";
    private static final String WEIGHTTOTAL = "weighttotal";
    private static final String VALUE = "value";
    private static final String VALUETOTAL = "valuetotal";
    private static final String DESCRIPTION = "description";

    public static synchronized DbHelper getInstance(Context context) {
        if (mDbHelper == null) {
            mDbHelper = new DbHelper(context.getApplicationContext());
        }
        return mDbHelper;
    }

    public DbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }


    @Override
    public void onCreate(SQLiteDatabase db) {

        String CREATE_USERDETAIL_TABLE = "CREATE TABLE " + TABLE_USERdETAIL +
                "(" +
                _ID + " INTEGER PRIMARY KEY , " +
                SORT_ID + " INTEGER," +
                NAME + " TEXT," +
                QUANTITY + " INTEGER," +
                WEIGHT + " INTEGER," +
                WEIGHTTOTAL + " INTEGER," +
                VALUE + " INTEGER," +
                VALUETOTAL + " INTEGER," +
                DESCRIPTION + " TEXT" +
                ")";

        db.execSQL(CREATE_USERDETAIL_TABLE);
    }



    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        if (oldVersion != newVersion) {
            db.execSQL("ALTER TABLE " + TABLE_USERdETAIL + " ADD COLUMN " + WEIGHT + " INTEGER DEFAULT 0");
            db.execSQL("ALTER TABLE " + TABLE_USERdETAIL + " ADD COLUMN " + WEIGHTTOTAL + " INTEGER DEFAULT 0");
            db.execSQL("ALTER TABLE " + TABLE_USERdETAIL + " ADD COLUMN " + VALUE + " INTEGER DEFAULT 0");
            db.execSQL("ALTER TABLE " + TABLE_USERdETAIL + " ADD COLUMN " + VALUETOTAL + " INTEGER DEFAULT 0");
        }
    }

    /**
   Insert a  user detail into database
   */
    public void insertUserDetail(UserData userData) {

        SQLiteDatabase db = getWritableDatabase();

        db.beginTransaction();

        try {
            ContentValues values = new ContentValues();
            values.put(SORT_ID, userData.sort_id);
            values.put(NAME, userData.name);
            values.put(QUANTITY, userData.quantity);
            values.put(WEIGHT, userData.weight);
            values.put(WEIGHTTOTAL, userData.weighttotal);
            values.put(VALUE, userData.value);
            values.put(VALUETOTAL, userData.valuetotal);
            values.put(DESCRIPTION, userData.description);


            db.insertOrThrow(TABLE_USERdETAIL, null, values);
            db.setTransactionSuccessful();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            db.endTransaction();
        }


    }

    public void updateUserDetail(int id, String v1, String v2, String v3, String v4, String v5, String v6, String v7){
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(NAME, v1);
        values.put(QUANTITY, v2);
        values.put(DESCRIPTION, v3);
        values.put(WEIGHT, v4);
        values.put(WEIGHTTOTAL, v5);
        values.put(VALUE, v6);
        values.put(VALUETOTAL, v7);
        db.update(TABLE_USERdETAIL, values, "_id="+id, null);
    }

   /**
   fetch all data from UserTable
    */
    public List<UserData> getAllUser() {
        List<UserData> usersdetail = new ArrayList<>();

        String USER_DETAIL_SELECT_QUERY = "SELECT * FROM " + TABLE_USERdETAIL + " ORDER BY " + SORT_ID + " COLLATE NOCASE;";

        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.rawQuery(USER_DETAIL_SELECT_QUERY, null);

        try {
            if (cursor.moveToFirst()) {
                do {
                    UserData userData = new UserData();
                    userData.id = cursor.getString(cursor.getColumnIndex(_ID));
                    userData.sort_id = cursor.getInt(cursor.getColumnIndex(SORT_ID));
                    userData.name = cursor.getString(cursor.getColumnIndex(NAME));
                    userData.quantity = "Quantity: " + cursor.getString(cursor.getColumnIndex(QUANTITY));
                    userData.weight = cursor.getString(cursor.getColumnIndex(WEIGHT));
                    userData.weighttotal = cursor.getString(cursor.getColumnIndex(WEIGHTTOTAL));
                    userData.value = cursor.getString(cursor.getColumnIndex(VALUE));
                    userData.valuetotal = cursor.getString(cursor.getColumnIndex(VALUETOTAL));
                    userData.description = cursor.getString(cursor.getColumnIndex(DESCRIPTION));

                    usersdetail.add(userData);
                } while (cursor.moveToNext());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (cursor != null && !cursor.isClosed()) {
                cursor.close();
            }
        }
        return usersdetail;

    }

    /**
   Delete single row from UserTable
     */
    void deleteRow(String name) {
        SQLiteDatabase db = getWritableDatabase();
        try {
            db.beginTransaction();
            db.execSQL("delete from " + TABLE_USERdETAIL + " where name ='" + name + "'");
            db.setTransactionSuccessful();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            db.endTransaction();
        }
    }

    void deleteRowItem(int id) {
        SQLiteDatabase db = getWritableDatabase();
        try {
            db.beginTransaction();
            db.execSQL("delete from " + TABLE_USERdETAIL + " where _id ='" + id + "'");
            db.setTransactionSuccessful();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            db.endTransaction();
        }
    }

    public UserData getSingleUserDetail(String userId) {
        SQLiteDatabase db = this.getWritableDatabase();
        UserData userData = null;

        //Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_USERdETAIL, null);

        // this is the code to order the RecyclerView by _ID:
        Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_USERdETAIL + " WHERE " + _ID + "= ?", new String[]{userId});
        try {
            while (cursor.moveToNext()) {
                userData = new UserData();
                userData.name = cursor.getString(cursor.getColumnIndex(NAME));
                userData.quantity = cursor.getString(cursor.getColumnIndex(QUANTITY));
                userData.weight = cursor.getString(cursor.getColumnIndex(WEIGHT));
                userData.weighttotal = cursor.getString(cursor.getColumnIndex(WEIGHTTOTAL));
                userData.value = cursor.getString(cursor.getColumnIndex(VALUE));
                userData.valuetotal = cursor.getString(cursor.getColumnIndex(VALUETOTAL));
                userData.description = cursor.getString(cursor.getColumnIndex(DESCRIPTION));
            }
            cursor.close();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (cursor != null && !cursor.isClosed()) {
                cursor.close();
            }
        }
        return userData;
    }

    public int getTotalWeight() {
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cur = db.rawQuery("SELECT SUM(WEIGHTTOTAL) FROM userdetail", null);
        if(cur.moveToFirst())
        {
            return cur.getInt(0);
        }
        cur.close();
        return getTotalWeight();
    }

    public int getTotalQuantity() {
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cur = db.rawQuery("SELECT SUM(QUANTITY) FROM userdetail", null);
        if(cur.moveToFirst())
        {
            return cur.getInt(0);
        }
        cur.close();
        return getTotalQuantity();
    }

    public int getTotalValue() {
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cur = db.rawQuery("SELECT SUM(VALUETOTAL) FROM userdetail", null);
        if(cur.moveToFirst())
        {
            return cur.getInt(0);
        }
        cur.close();
        return getTotalValue();
    }

    public int getMaxColumnData() {
        SQLiteDatabase db = this.getWritableDatabase();
        final SQLiteStatement stmt = db
                .compileStatement("SELECT MAX(SORT_ID) FROM " + TABLE_USERdETAIL);

        return (int) stmt.simpleQueryForLong();
    }

    public void updateUserData(UserData userData) {

        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();

        values.put(NAME, userData.getName());
        values.put(QUANTITY, userData.getQuantity());
        values.put(DESCRIPTION, userData.getDescription());
        values.put(WEIGHT, userData.getWeight());
        values.put(WEIGHTTOTAL, userData.getWeighttotal());
        values.put(VALUE, userData.getValue());
        values.put(VALUETOTAL, userData.getValuetotal());
        values.put(SORT_ID, userData.getSort());

        Log.i("DBhelper", "USER UPDATED = " + userData.getName());

        db.update(TABLE_USERdETAIL, values, _ID + "=?", new String[]{String.valueOf(userData.getId())});

    }
}

UserData​​h2 > 

import java.io.Serializable;

public class UserData implements Serializable {
    String id, name, quantity, weight, weighttotal, value, valuetotal, description;
    int sort_id;

    public UserData() {
        super();
    }

    public void setId(String id){
        this.id= id;
    }
    public String getId(){
        return id;
    }
    public void setSort(int sort){
        this.sort_id= sort;
    }
    public int getSort(){
        return sort_id;
    }

    public void setName(String name){
        this.name= name;
    }
    public String getName(){
        return name;
    }
    public void setDescription(String description){
        this.description= description;
    }
    public String getDescription(){
        return description;
    }
    public void setQuantity(String quantity){
        this.quantity= quantity;
    }
    public String getQuantity(){
        return quantity;
    }
    public void setWeight(String weight){
        this.weight= weight;
    }
    public String getWeight(){
        return weight;
    }
    public void setWeighttotal(String weighttotal){
        this.weighttotal= weighttotal;
    }
    public String getWeighttotal(){
        return weighttotal;
    }
    public void setValue(String value){
        this.value= value;
    }
    public String getValue(){
        return value;
    }
    public void setValuetotal(String valuetotal){
        this.quantity= valuetotal;
    }
    public String getValuetotal(){
        return quantity;
    }
}

Класс ItemTouchHelperViewHolder

public interface ItemTouchHelperViewHolder {
    void onItemSelected();
    void onItemClear();
}

MainActivity

public class MainActivity extends AppCompatActivity implements ListAdapter.Listener {


    RecyclerView recyclerView;
    DbHelper dbHelper;
    ListAdapter adapter;
    private ItemTouchHelper mItemTouchHelper;

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


        dbHelper = DbHelper.getInstance(getApplicationContext());

        recyclerView = (RecyclerView) findViewById(R.id.rv_contactlist);
        adapter = new ListAdapter(this, dbHelper.getAllUser());
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        ItemTouchHelper.Callback callback =
                new SimpleItemTouchHelperCallback(adapter);
        mItemTouchHelper = new ItemTouchHelper(callback);
        mItemTouchHelper.attachToRecyclerView(recyclerView);

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main_menu, menu);
        return super.onCreateOptionsMenu(menu);


    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.about_task:
                Intent intentChangeActivity2 = new Intent(MainActivity.this, AboutActivity.class);
                startActivity(intentChangeActivity2);
                return true;
            case R.id.encumbrance_task:
                Intent intentChangeActivity = new Intent(MainActivity.this, EncumbranceActivity.class);
                startActivity(intentChangeActivity);
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    @Override
    public void onResume() {
        super.onResume();
        dbHelper = DbHelper.getInstance(getApplicationContext());

        recyclerView = (RecyclerView) findViewById(R.id.rv_contactlist);
        adapter = new ListAdapter(this, dbHelper.getAllUser());
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

    }

    @Override
    public void nameToChnge(String name) {
        dbHelper.deleteRow(name);

        adapter = new ListAdapter(this, dbHelper.getAllUser());
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
    }

}

Журнал ошибок:

8-26 11:20:49.443 23533-23533/name.appE/AndroidRuntime: FATAL EXCEPTION: main
                                                                       Process: name.app, PID: 23533
                                                                       java.lang.NullPointerException: Attempt to invoke virtual method 'void name.app.DbHelper.updateUserData(name.app.UserData)' on a null object reference
                                                                           at name.app.ListAdapter$ListViewHolder.onItemClear(ListAdapter.java:95)
                                                                           at name.app.SimpleItemTouchHelperCallback.clearView(SimpleItemTouchHelperCallback.java:63)
                                                                           at android.support.v7.widget.helper.ItemTouchHelper$3.onAnimationEnd(ItemTouchHelper.java:619)
                                                                           at android.support.v4.animation.HoneycombMr1AnimatorCompatProvider$AnimatorListenerCompatWrapper.onAnimationEnd(HoneycombMr1AnimatorCompatProvider.java:115)
                                                                           at android.animation.ValueAnimator.endAnimation(ValueAnimator.java:1149)
                                                                           at android.animation.ValueAnimator.doAnimationFrame(ValueAnimator.java:1309)
                                                                           at android.animation.AnimationHandler.doAnimationFrame(AnimationHandler.java:146)
                                                                           at android.animation.AnimationHandler.-wrap2(AnimationHandler.java)
                                                                           at android.animation.AnimationHandler$1.doFrame(AnimationHandler.java:54)
                                                                           at android.view.Choreographer$CallbackRecord.run(Choreographer.java:869)
                                                                           at android.view.Choreographer.doCallbacks(Choreographer.java:683)
                                                                           at android.view.Choreographer.doFrame(Choreographer.java:616)
                                                                           at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857)
                                                                           at android.os.Handler.handleCallback(Handler.java:751)
                                                                           at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                           at android.os.Looper.loop(Looper.java:154)
                                                                           at android.app.ActivityThread.main(ActivityThread.java:6123)
                                                                           at java.lang.reflect.Method.invoke(Native Method)
                                                                           at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
                                                                           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)

ОТВЕТЫ

Ответ 1

Я не уверен, что поймаю вашу проблему, но то, что я заметил (надеюсь, что это помогает): в onItemMove вы переформатируете dataList путем замены элементов, но адаптер уведомляет об общих изменениях.

Угадайте самый простой способ перемещения элемента (и сохранить анимацию) - удалить его и снова добавить:

UserData item = dataList.remove(fromPosition);
dataList.add(i, toPossition);
notifyItemMoved(fromPosition, toPosition);

Ответ 2

Я не уверен в вашей проблеме. Но я реализовал то же самое с использованием данного кода. Этот код не использует SQLite, но он выполняет перетаскивание в ресайклере с некоторыми текстовыми комментариями. Вы можете посмотреть мой код:

MovieTouchHelper.java

public class MovieTouchHelper extends ItemTouchHelper.SimpleCallback {
private MovieAdapter mMovieAdapter;

public MovieTouchHelper(MovieAdapter movieAdapter){
    super(ItemTouchHelper.UP | ItemTouchHelper.DOWN, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT);
    this.mMovieAdapter = movieAdapter;
}

@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
    mMovieAdapter.swap(viewHolder.getAdapterPosition(), target.getAdapterPosition());
    return true;
}

@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
    mMovieAdapter.remove(viewHolder.getAdapterPosition());
}
}

MovieAdapter.java

public class MovieAdapter extends RecyclerView.Adapter<MovieAdapter.ViewHolder> {
private Context mContext;
private List<Movie> mMovies;

public MovieAdapter(Context context, List<Movie> movies){
    this.mContext = context;
    this.mMovies = movies;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    return new ViewHolder(LayoutInflater.from(mContext).inflate(R.layout.list_item_movie, parent, false));
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    holder.bindMovie(mMovies.get(position));
}

@Override
public int getItemCount() {
    return mMovies.size();
}

public void remove(int position) {
    mMovies.remove(position);
    notifyItemRemoved(position);
}

public void swap(int firstPosition, int secondPosition){
    Collections.swap(mMovies, firstPosition, secondPosition);
    notifyItemMoved(firstPosition, secondPosition);
}

public class ViewHolder extends RecyclerView.ViewHolder{
    public final TextView movieNameTextView;

    public ViewHolder(View view){
        super(view);
        movieNameTextView = (TextView) view.findViewById(R.id.movie_name);
    }

    public void bindMovie(Movie movie){
        this.movieNameTextView.setText(movie.getName());
    }
}
}

Вы можете отредактировать код в соответствии с вашими потребностями. Надеюсь, это поможет!

Ответ 3

EDITED: Посмотрите на полный пример здесь

Я проверил ваш код, и ваш метод OnItemMove работает должным образом. Возможно, у вас есть проблемы с сохранением заказа в вашей базе данных?

Здесь у вас есть пример:

1- Создать интерфейс ItemTouchHelperViewHolder:

public interface ItemTouchHelperViewHolder {
    void onItemSelected();
    void onItemClear();
}

Теперь реализуйте его в своем классе ViewHolder.

2- Перейдите в класс SimpleItemTouchHelperCallback и добавьте два метода:

@Override
    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
        if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
            if (viewHolder instanceof ItemTouchHelperViewHolder) {
                ItemTouchHelperViewHolder itemViewHolder = 
                (ItemTouchHelperViewHolder) viewHolder;
                itemViewHolder.onItemSelected();
            }
        }
        super.onSelectedChanged(viewHolder, actionState);
    }
@Override
    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        super.clearView(recyclerView, viewHolder);

        if (viewHolder instanceof ItemTouchHelperViewHolder) {
            // Tell the view holder it time to restore the idle state
            ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
            itemViewHolder.onItemClear();
        }
    }

3- В OnItemClear (класс ViewHolder) сохраните новый порядок:

 @Override
        public void onItemClear() {
            for (int count = 0; count < dataList.size(); count++) {
                UserData u = dataList.get(count);
                u.setOrder(count);
                mDbHelper.updateOrder(u);
            }
            adapter.notifyDataSetChanged();
        }

Ответ 4

В onItemMove вам не нужно делать все swap, потому что метод будет вызываться каждый раз, когда выбранный элемент изменит свою позицию с помощью элемента рядом с ним. Поэтому каждая итерация в for будет заботиться о каждом вызове метода.

вам следует переместить элемент из старой позиции (dragged.getAdapterPosition()) в новую позицию (target.getAdapterPosition()) в свой адаптер, а также вызвать RecyclerView.Adapter.notifyItemMoved(int, int).

Ваш onItemMove должен выглядеть примерно так:

@Override
public void onItemMove(int fromPosition, int toPosition) {
    Collections.swap(mItems, fromPosition, toPosition);
    notifyItemMoved(fromPosition, toPosition);
}