gridview(그리드뷰) getview호출 문제

Question

protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  requestWindowFeature(Window.FEATURE_NO_TITLE);
  getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
    WindowManager.LayoutParams.FLAG_FULLSCREEN);
  setContentView(R.layout.plant_list);
        initSildeMenu();
        gridView = (GridView)findViewById(R.id.gridView1);
        MyGridAdapter gAdapter = new MyGridAdapter(plant_list_Activity.this);
        gAdapter.setDf1(df);
        gAdapter.notifyDataSetChanged();
        gridView.setAdapter((ListAdapter) gAdapter);
    }
  public class MyGridAdapter extends BaseAdapter {
        Context context;

        public MyGridAdapter(Context c) {
            context = c;
        }
        @Override
        public int getCount() {
            return df.size();

        }

        @Override
        public Object getItem(int arg0) {
            return null;
        }

        @Override
        public long getItemId(int arg0) {
            return 0;
        }

        ArrayList<Bitmap> df1 = new ArrayList<Bitmap>();

        public void setDf1(ArrayList<Bitmap> df1) {
            this.df1 = df;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView imageview;
            if(convertView == null) {

            imageview = new ImageView(context);
            imageview.setLayoutParams(new GridView.LayoutParams(400, 350)); //이미지뷰 사이즈
            imageview.setScaleType(ImageView.ScaleType.FIT_CENTER);
            imageview.setPadding(20, 20, 20, 20);
            }
            else
                imageview = (ImageView)convertView;

            imageview.setImageBitmap(df1.get(position));
            final int pos = position; //비트맵배열 순서

           return imageview;
        }
    }

위와같이 생성하였습니다. 현재 activity를 화면에 띄우면 그리드뷰가 뜨진 않습니다만 화면에 투터치(손가락 2개로 화면클릭) 또는 왼쪽에 만들어 놓은 버튼 슬라이드 선택시 그리드뷰가 뜨게 됩니다.

adapter 갱신도 해보고 이것저것 손 봤는데 계속 같네요.어떻게 하면 바로 화면에 그리드뷰가 뜰까요?