Как загрузить базу данных SQlite в Recyclerview?

Question

У меня есть recyclerview внутри активности фрагмента, которая использует кнопку для вызова диалогового окна предупреждения, чтобы получить ввод для двух строковых переменных. Я успешно создал базу данных и могу добавлять элементы в базу данных из ввода alertdialog, но я хочу заполнить recyclerview базой данных, когда приложение изначально запускается. База данных используется для хранения ввода, и я хочу, чтобы она заполнила recyclerview, чтобы пользователь мог видеть элементы, которые они ввели ранее.

Это мой фрагмент:

public class tab1Expenses extends Fragment { 

SqlDatabase dbEntry; 

ArrayList<ExRow> expenseList = new ArrayList<>(); 
RecyclerView recyclerView; 
ExpensesAdapter mAdapter; 
Button btnEx; 
String Na; 
String Am; 
String message = "Name must be longer than 2 characters"; 
String message2 = "Please enter valid amount"; 
Double value; 
String am; 

public void expenseData() { 
    ExRow exs = new ExRow(Na, Am); 
    expenseList.add(exs); 
    mAdapter.notifyDataSetChanged(); 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    final View rootView = inflater.inflate(R.layout.tab1expense, container, false); 
    btnEx = (Button) rootView.findViewById(R.id.btnEx); 
    recyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view); 
    recyclerView.addItemDecoration(new DividerItemDecoration(tab1Expenses.this.getActivity(), LinearLayoutManager.VERTICAL)); 

    mAdapter = new ExpensesAdapter(expenseList); 
    final RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(this.getActivity()); 

    recyclerView.setHasFixedSize(true); 
    recyclerView.setClickable(true); 
    recyclerView.isFocusable(); 
    recyclerView.setFocusableInTouchMode(true); 
    recyclerView.setLayoutManager(mLayoutManager); 
    recyclerView.setItemAnimator(new DefaultItemAnimator()); 
    recyclerView.setAdapter(mAdapter); 

    btnEx.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      //Brings up Alert Dialog when Add income button is pressed 
      add(); 
     } 
    }); 
    return rootView; 
} 


public int add() { 
    View view = LayoutInflater.from(tab1Expenses.this.getActivity()) 
      .inflate(R.layout.add_ex, null); 
    final EditText txtExName = (EditText) view.findViewById(R.id.exName); 
    final EditText txtExAmount = (EditText) view.findViewById(R.id.exAmount); 
    //Creates Alert Dialog 
    AlertDialog.Builder add = new AlertDialog.Builder(tab1Expenses.this.getActivity()); 
    add.setCancelable(true) 
      .setTitle("Enter Expense:") 
      .setView(view) 
      .setPositiveButton("Add", 
        //AlertDialog positive button ClickListener 
        new DialogInterface.OnClickListener() { 
         @Override 
         public void onClick(DialogInterface dialog, int which) { 
          //Checks for invalid input 
          //If criteria met, expenseData() is called 
          if (txtExAmount.getText().length() > 0 && txtExName.getText().length() > 2 && txtExAmount.getText().length() < 6 && txtExName.getText().length() < 25) { 
           Na = txtExName.getText().toString(); 
           am = txtExAmount.getText().toString(); 
           value = Double.parseDouble(am); 
           Am = NumberFormat.getCurrencyInstance().format(value); 
           expenseData(); 

          } 
          //Toast for invalid input 
          if (txtExName.getText().length() <= 2) { 
           Toast.makeText(tab1Expenses.this.getActivity(), message, Toast.LENGTH_SHORT).show(); 
          } else if (txtExAmount.getText().length() == 0) { 
           Toast.makeText(tab1Expenses.this.getActivity(), message2, Toast.LENGTH_SHORT).show(); 
          } else if (txtExAmount.getText().length() >= 6) { 
           Toast.makeText(tab1Expenses.this.getActivity(), "You don't make that much", Toast.LENGTH_SHORT).show(); 
          } else if (txtExName.getText().length() >= 25) { 
           Toast.makeText(tab1Expenses.this.getActivity(), "Name must be less than 25 characters", Toast.LENGTH_SHORT).show(); 
          } 
         } 
        }); 
    Dialog dialog = add.create(); 
    dialog.show(); 

    return 0; 
} 

public void viewAll() { 

     ExRow exrow = new ExRow(); 
     Cursor res = dbEntry.getAllData(); 
     exrow.setTitle(res.getString(1)); 
     exrow.setAmount(res.getString(2)); 

    } 
} 

Это моя база данных:

public class SqlDatabase extends SQLiteOpenHelper { 
private static final String DATABASE_NAME = "Expenses.db"; 
public static final String TABLE_NAME = "Expense_Table"; 
public static final String ID = "id"; 
public static final String Col_NAME = "Na"; 
public static final String Col_AMOUNT = "Am"; 


    public SqlDatabase(Context context) { 
     super(context, DATABASE_NAME, null, 1); 
    } 

    @Override 
    //Set up database here 
    public void onCreate(SQLiteDatabase db) { 
     db.execSQL("Create table " + TABLE_NAME + 
       "(ID INTEGER PRIMARY KEY AUTOINCREMENT,NAME TEXT, AMOUNT TEXT)"); 

    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME); 
     onCreate(db); 
    } 
    public boolean insertData(String Na, String Am) { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     ContentValues contentValues = new ContentValues(); 
     contentValues.put(Col_NAME, Na); 
     contentValues.put(Col_AMOUNT, Am); 
     long result = db.insert(TABLE_NAME, null, contentValues); 
     if (result == -1) { 
      return false; 
     } else { 
      return true; 
     } 

    } 
public static Cursor getAllData() { 
    SQLiteDatabase db = this.getWritableDatabase(); 
    Cursor res = db.rawQuery("select * from " + TABLE_NAME, null); 
    return res; 

} 
} 

И это мой RecyclerView адаптер + Посмотреть держатель:

public class ExpensesAdapter extends RecyclerView.Adapter<ExpensesAdapter.MyViewHolder> { 
public ImageButton mRemoveButton; 
private ArrayList<ExRow> expenseList; 

public class MyViewHolder extends RecyclerView.ViewHolder { 
    public TextView title, amount; 

    public MyViewHolder(View view) { 
     super(view); 
     title = (TextView) view.findViewById(R.id.name); 
     amount = (TextView) view.findViewById(R.id.amount); 
     mRemoveButton = (ImageButton) view.findViewById(R.id.ib_remove); 
    } 
} 

public ExpensesAdapter(ArrayList<ExRow> expenseList) { 
    this.expenseList = expenseList; 
} 

@Override 
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View itemView = LayoutInflater.from(parent.getContext()) 
      .inflate(R.layout.expense_list, parent, false); 

    return new MyViewHolder(itemView); 
} 

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

    ExRow expense = expenseList.get(holder.getAdapterPosition()); 
    holder.title.setText(expense.getTitle()); 
    holder.amount.setText(expense.getAmount()); 
    mRemoveButton.setOnClickListener(new View.OnClickListener() { 
     public void onClick(View view) { 
      // Remove the item on remove/button click 
      int adapterPosition = holder.getAdapterPosition(); 

      expenseList.remove(adapterPosition); 
      notifyItemRemoved(adapterPosition); 
      notifyDataSetChanged(); 
     } 
    }); 
} 
@Override 
public int getItemCount() { 
    return expenseList.size(); 

Answer 1

Вы должны получить список вашего ExRow вместо курсора в вашем SQLiteOpenH elper. Таким образом, вместо:

public static Cursor getAllData() { 
    SQLiteDatabase db = this.getWritableDatabase(); 
    Cursor res = db.rawQuery("select * from " + TABLE_NAME, null); 
    return res; 

} 

Вы должны вернуть список с чем-то вроде этого:

// Your column 
private String[] allColumns = { "ID", "COLUMN_1", "COLUMN_2" }; 

public List<ExRow> getAllData() { 
    List<ExRow> exrows = new ArrayList<>(); 

    Cursor cursor = database.query("YOUR_TABLE", allColumns, null, null, 
            null, null, null); 

    if (cursor != null && cursor.moveToFirst()) { 
     while (!cursor.isAfterLast()) { 

     ExRow exrow = populateModel(cursor); 
     exrows.add(exrow); 
     cursor.moveToNext(); 
     } 
     cursor.close(); 
    } 
    return exrows; 
    } 


private ExRow populateModel(Cursor c) { 
    ExRow model = new ExRow(); 
    model.setId(c.getLong("ID")); 
    model.setColumn1(c.getString(c.getColumnIndex("COLUMN_1"))); 
    model.setColumn2(c.getString(c.getColumnIndex("COLUMN_2"))); 

    return model; 
} 

Затем вы можете использовать возвращаемое значение из getAllData() и передать его в адаптер.