Android-ListView中getView

public class MultipleItemsList extends ListActivity {   private MyCustomAdapter mAdapter;   @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mAdapter = new MyCustomAdapter(); for (int i = 0; i < 50; i++) { mAdapter.addItem("item " + i); } setListAdapter(mAdapter); }   private class MyCustomAdapter extends BaseAdapter {   private ArrayList mData = new ArrayList(); private LayoutInflater mInflater;   public MyCustomAdapter() { mInflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE); }   public void addItem(final String item) { mData.add(item); notifyDataSetChanged(); }   @Override public int getCount() { return mData.size(); }   @Override public String getItem(int position) { return mData.get(position); }   @Override public long getItemId(int position) { return position; }   @Override public View getView(int position, View convertView, ViewGroup parent) { System.out.println("getView " + position + " " + convertView); ViewHolder holder = null; if (convertView == null) { convertView = mInflater.inflate(R.layout.item1, null); holder = new ViewHolder(); holder.textView = (TextView)convertView.findViewById(R.id.text); convertView.setTag(holder); } else { holder = (ViewHolder)convertView.getTag(); } holder.textView.setText(mData.get(position)); return convertView; }   }   public static class ViewHolder { public TextView textView; } }