使listView中有些条目可用，有些不可用
有时候，我们需要listView中有些条目可用，有些不可用。如何设置呢？
其实很简单，只要重写isEnabled(int position)就可以了，看下面的例子.

public class List5 extends ListActivity {    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setListAdapter(new MyListAdapter(this));    }    private class MyListAdapter extends BaseAdapter {        public MyListAdapter(Context context) {            mContext = context;        }        public int getCount() {            return mStrings.length;        }        @Override        public boolean areAllItemsEnabled() {            return true;        }        @Override        public boolean isEnabled(int position) {            return !mStrings[position].startsWith("-");        }        public Object getItem(int position) {            return position;        }        public long getItemId(int position) {            return position;        }        public View getView(int position, View convertView, ViewGroup parent) {            TextView tv;            if (convertView == null) {                tv = (TextView) LayoutInflater.from(mContext).inflate(                        android.R.layout.simple_expandable_list_item_1, parent, false);            } else {                tv = (TextView) convertView;            }            tv.setText(mStrings[position]);            return tv;        }        private Context mContext;    }        private String[] mStrings = {            "----------",            "----------",            "Abbaye de Belloc",            "Abbaye du Mont des Cats",            "Abertam",            "----------",            "Abondance",            "----------",            "Ackawi",            "Acorn",            "Adelost",            "Affidelice au Chablis",            "Afuega'l Pitu",            "Airag",            "----------",            "Airedale",            "Aisy Cendre",            "----------",            "Allgauer Emmentaler",            "Alverca",            "Ambert",            "American Cheese",            "Ami du Chambertin",            "----------",            "----------",            "Anejo Enchilado",            "Anneau du Vic-Bilh",            "Anthoriro",            "----------",            "----------"    };}