میشه یکی جواب بده (مشکل در خواندن دیتابیس)

اینم کد

 public class ActivityDatabase extends SQLiteOpenHelper {

    public final String   path = "data/data/com.elham.app.chocolate/databases/";
    public final String   Name = "database";
    public SQLiteDatabase mydb;
    private final Context mycontext;


    public ActivityDatabase(Context context) {
        super(context, "database", null, 1);
        mycontext = context;
    }


    @Override
    public void onCreate(SQLiteDatabase db) {

    }


    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }


    public void useable() {

        boolean checkdb = checkdb();

        if (checkdb) {

        } else {
            this.getReadableDatabase();
            try {
                copydatabase();
            }
            catch (IOException e) {

            }
        }
    }


    public void open() {

        mydb = SQLiteDatabase.openDatabase(path + Name, null, SQLiteDatabase.OPEN_READWRITE);
    }


    public void close() {
        mydb.close();
    }


    public boolean checkdb() {
        SQLiteDatabase db = null;

        try {
            db = SQLiteDatabase.openDatabase(path + Name, null, SQLiteDatabase.OPEN_READONLY);

        }
        catch (SQLException e) {}

        return db != null ? true : false;

    }


    public void copydatabase() throws IOException {

        OutputStream myOutput = new FileOutputStream(path + Name);

        byte[] buffer = new byte[1024];
        int length;

        InputStream myInput = mycontext.getAssets().open(Name);
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }

        myInput.close();
        myOutput.flush();
        myOutput.close();

    }


    public String Display(int row, int field, String table) {
        Cursor cu = mydb.rawQuery("select * from" + table, null);
        cu.moveToPosition(row);
        String s = cu.getString(field);
        return s;
    }

}

اینم دستورات اجرا 

 
public class ChocolateActivity extends Activity {

    private ActivityDatabase db;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button btn = (Button) findViewById(R.id.button1);
        db = new ActivityDatabase(this);

        db.useable();

        btn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {

                db.open();
                String s = db.Display(0, 1, "chocolate");
                Toast.makeText(getApplicationContext(), s, Toast.LENGTH_LONG).show();
                db.close();
            }

        });

    }
}