android 中自定义GridView的使用_course

楼主最近在学习安卓，用和ListView类似的方法实现Gridview的时候出现了问题。希望高手能指点一二。 aty_using_gridview.xml ``` <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <GridView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/gridView" android:numColumns="3"/> </LinearLayout> ``` grid_view_cell.xml ``` <?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="100dp" android:layout_height="100dp"> <ImageView android:layout_width="100dp" android:layout_height="100dp" android:id="@+id/img_grid_view" /> </FrameLayout> ``` 这个是Activity ``` public class AtyUsingGridView extends Activity { private GridView gridView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.aty_using_gridview); ImageGridViewAdapter adapter=new ImageGridViewAdapter(this); gridView.findViewById(R.id.gridView); gridView.setAdapter(adapter); } } ``` 这个是adapter ``` public class ImageGridViewAdapter extends BaseAdapter { private Context context=null; private ImageGridViewData data[]= { new ImageGridViewData( R.drawable.img2), new ImageGridViewData(R.drawable.img2), new ImageGridViewData( R.drawable.img2), }; public ImageGridViewAdapter(Context context){ this.context=context; } public Context getContext() { return context; } @Override public int getCount() { return data.length; } @Override public ImageGridViewData getItem(int i) { return data[i]; } @Override public long getItemId(int i) { return i; } @Override public View getView(int i, View view, ViewGroup viewGroup) { FrameLayout fl=null; if(view!=null){ fl=( FrameLayout)view; }else{ fl= ( FrameLayout) LayoutInflater.from(getContext()).inflate(R.layout.grid_view_cell,null); } ImageGridViewData data=getItem(i); ImageView imgID=(ImageView)fl.findViewById(R.id.img_grid_view); imgID.setImageResource(data.imgID); return fl; } } ``` 运行出现错误如下 Unable to start activity java.lang.NullPointerException 我这有什么错误，希望高手给指出啊，万分感谢。