public class MainActivity extends AppCompatActivity {

    Button testbtn,cancelbtn;
    TextView tt;
    String TAG="check";


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

        tt = (TextView)findViewById(R.id.tt);
        testbtn = (Button)findViewById(R.id.testButton);
        testbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                DatabaseAccess databaseAccess = DatabaseAccess.getInstance(getApplicationContext());
                databaseAccess.open();
                String getdata = databaseAccess.getquestion();
                tt.setText(getdata);
                databaseAccess.close();

            }
        });

        cancelbtn =(Button)findViewById(R.id.cancelButton);
        cancelbtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                tt.setText("");
            }
        });


        }

}

public class DatabaseOpenHelper extends SQLiteAssetHelper{

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

    public DatabaseOpenHelper(Context context){

        super(context,DB_NAME,null,DB_VERSION);

    }
}

public class DatabaseAccess {

    private SQLiteOpenHelper openHelper;
    private SQLiteDatabase db;
    private static DatabaseAccess instance;
    Cursor c=null;
    Cursor c2 =null;
    private String getDataByNumber ="select qanda from tb1 where Number=  ";
    private String getNumberOfRecords ="select Number from tb1";

    private DatabaseAccess(Context context){

        this.openHelper = new DatabaseOpenHelper(context);
    }

    public static DatabaseAccess getInstance(Context context){

        if(instance==null){
            instance = new DatabaseAccess(context);
        }

        return instance;
    }

    public void open(){
        this.db =openHelper.getReadableDatabase();
    }

    public void close() {
        if (db != null) {
            this.db.close();
        }
    }

    public String getquestion(){

        c2=db.rawQuery(getNumberOfRecords,null);
        int count =0;
        c2.moveToLast();
        int questionNumber = c2.getInt(0); // Get number of records
        count = questionNumber;
        c2.close();


        int r = (int) (Math.random()*count +1 );  //  Get random text
        c=db.rawQuery(getDataByNumber+r,null);
        String data =null;

        while(c.moveToNext()){
            String question = c.getString(0);
            data = question;
            }
            c.close();

        return data+count;

    }
}