从sqlite到自定义适配器android的多行

Question

该应用程序：我有一个应用程序可以创建多台计算机，其中包括：

• ID，名称和位置

这些机器中的每一个我都必须让用户输入收入

• id，注释，日期，金钱，machines_id

问题：我需要将所有注释从匹配的machine_id填充到ListView 。

我尝试了什么：创建DBHelper方法来获取我需要的信息（注释和日期） 。

• db.rawQuery（“ SELECT note，date FROM FROM WHERE machines_id =” + machinesId +“”，空）；

目前，这适用于SQLite的数据库浏览器，但我不知道如何将其添加到ListView适配器并将其设置为相应的TextView

我的问题：完成DBHelper方法和自定义适配器之间的结合以仅获取TextViews所需信息的最佳方法是什么？ （来自匹配的machines_id的日期和注释）

如果您需要其他课程或有任何反馈，请不要犹豫，放纵我！

数据库助手

    public class DBHelpter extends SQLiteOpenHelper {

    private static final String DB_NAME = "machines.db";
    private static final int DB_VERSION = 1;

    public static final String TABLE_MACHINES = "machines";
    public static final String MACHINES_COLUMN_NAME = "name";
    public static final String MACHINES_COLUMN_LOCATION = "location";
    public static final String MACHINES_ID = "id";

    public static final String TABLE_INCOME = "income";
    public static final String INCOME_COLUMN_MONEY = "money";
    public static final String INCOME_COLUMN_DATE = "date";
    public static final String INCOME_COLUMN_NOTE = "note";
    public static final String INCOME_ID = "id";
    public static final String INCOME_COLUMN_MACHINES_ID = "machines_id";

    private Context mContext;

public DBHelpter(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }

@Override
public void onCreate(SQLiteDatabase db) {
    String query1 = String.format("CREATE TABLE " + TABLE_MACHINES + "("
        + MACHINES_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
        + MACHINES_COLUMN_NAME + " TEXT NOT NULL, "
        + MACHINES_COLUMN_LOCATION + " TEXT NOT NULL)",
            TABLE_MACHINES, MACHINES_COLUMN_NAME, MACHINES_COLUMN_LOCATION, MACHINES_ID);

    String query2 = String.format("CREATE TABLE " + TABLE_INCOME + "("
        + INCOME_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
        + INCOME_COLUMN_MONEY + " REAL NOT NULL, "
        + INCOME_COLUMN_DATE + " DATE NOT NULL, "
        + INCOME_COLUMN_NOTE + " TEXT NOT NULL, "
        + INCOME_COLUMN_MACHINES_ID + " INTEGER NOT NULL)",
            TABLE_INCOME, INCOME_ID, INCOME_COLUMN_MONEY, INCOME_COLUMN_DATE, INCOME_COLUMN_NOTE, INCOME_COLUMN_MACHINES_ID);
    db.execSQL(query1);
    db.execSQL(query2);

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    String query1 = String.format("DROP TABLE IF EXISTS " + TABLE_MACHINES);
    String query2 = String.format("DROP TABLE IF EXISTS " + TABLE_INCOME);
    db.execSQL(query1);
    db.execSQL(query2);
    onCreate(db);

}
public void insertNewMachine(String name, String location){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(MACHINES_COLUMN_NAME, name);
        values.put(MACHINES_COLUMN_LOCATION, location);
        db.insertWithOnConflict(TABLE_MACHINES, null, values, SQLiteDatabase.CONFLICT_REPLACE);
        db.close();
    }
public void insertNewIncome(Double money, String date, String note, long machines_id){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(INCOME_COLUMN_MONEY, money);
        values.put(INCOME_COLUMN_DATE, date);
        values.put(INCOME_COLUMN_NOTE, note);
        values.put(INCOME_COLUMN_MACHINES_ID, machines_id);
        db.insertWithOnConflict(TABLE_INCOME, null, values, SQLiteDatabase.CONFLICT_REPLACE);
        db.close();
    }
public void getIncomeOfMachine(long machinesId){
        SQLiteDatabase db = getReadableDatabase();
    Cursor cursor = db.rawQuery("SELECT machines_id, SUM(money) AS total FROM income WHERE machines_id = "+machinesId+"", null);
    cursor.moveToFirst();
    double total_amount = cursor.getDouble(cursor.getColumnIndex("total"));
    return total_amount;
    }
public ArrayList<MachinesClass> getAllMachines(){
        ArrayList<MachinesClass> machinesList = new ArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery("SELECT * FROM "+ TABLE_MACHINES, null);
        while (cursor.moveToNext()){
            final long id = cursor.getLong(cursor.getColumnIndex(MACHINES_ID));
            final String name = cursor.getString(cursor.getColumnIndex(MACHINES_COLUMN_NAME));
            final String location = cursor.getString(cursor.getColumnIndex(MACHINES_COLUMN_LOCATION));
            machinesList.add(new MachinesClass(id, name, location));
        }
        cursor.close();
        db.close();
        return machinesList;
    }

public ArrayList<String> getInfoFromMachine(long machinesId){
        ArrayList<String> all_notes = new ArrayList<>();
        SQLiteDatabase db = getReadableDatabase();
        Cursor cursor = db.rawQuery("SELECT note, date FROM income WHERE machines_id = "+machinesId+"",null);
        cursor.moveToFirst();
        while (cursor.moveToNext()){
            String note = cursor.getString(cursor.getColumnIndex("note"));
            String date = cursor.getString(cursor.getColumnIndex("date"));
            all_notes.add(date);
            all_notes.add(note);
        }
        db.close();
        cursor.close();
        return all_notes;
    }
}

列表适配器

    public class ListAdapter extends BaseAdapter {

    private Context mContext;
    private DBHelpter mDBHelpter;
    private ArrayList<IncomeClass> mList;

    public ListAdapter(Context mContext, DBHelpter mDBHelper, ArrayList<IncomeClass> mList){
        this.mContext = mContext;
        this.mDBHelpter = mDBHelper;
        this.mList = mList;
    }

    @Override
    public int getCount() {
        return mList != null ? mList.size(): 0;
    }

    @Override
    public Object getItem(int position) {
        return mList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        mDBHelpter = new DBHelpter(mContext);
        SQLiteDatabase db = mDBHelpter.getReadableDatabase();
        ViewHolder viewHolder;

        if (convertView == null){
            convertView = LayoutInflater.from(mContext).inflate(R.layout.notes_list, parent, false);
            viewHolder = new ViewHolder(convertView);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }



//        Cursor info = mDBHelpter.getInfoFromMachine(currentNote.getId());
//        viewHolder.mNote.setText(mDBHelpter.getInfoFromMachine(currentNote.getId()).toString());
//        viewHolder.mNoteDate.setText(mDBHelpter.getInfoFromMachine(currentNote.getId()).toString());

        return convertView;
    }

    private class ViewHolder {
        private TextView mNote, mNoteDate;

        public ViewHolder(View view){
            mNote = (TextView) view.findViewById(R.id.tvNote);
            mNoteDate = (TextView) view.findViewById(R.id.tvNoteDate);
        }
    }
}

Answer 1

基本上，执行查询时，数据库将返回Cursor对象。 该游标将包含数据库中所有返回的行。 您可以使用CursorAdapter或将Cursor传递给自定义适配器的构造函数。

这是一个非常简单的示例，说明如何使用RecyclerView适配器实现该目标。

public class RecyclerViewCursorAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {

    private Cursor mCursor;
    private int mRowIdColumn;

    // Pass the cursor to your adapter.
    public void RecyclerViewCursorAdaper(Cursor cursor) {
        mCursor = cursor;
        mRowIdColumn = mCursor.getColumnIndex("_id");
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // Inflate your view here.
        return null;
    }

    @Override
    public long getItemId(int position) {
        if (mCursor != null && mCursor.moveToPosition(position)) {
            return mCursor.getLong(mRowIdColumn);
        }
        return 0;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        mCursor.moveToPosition(position);
        // Todo: Bind your custom view holder.
    }

    @Override
    public int getItemCount() {
        if (mCursor != null) {
            return mCursor.getCount();
        }
        return 0;
    }

    public Cursor getCursor() {
        return mCursor;
    }
}