Adapter的getViewTypeCount和getItemViewType
不同的项目布局(item layout)
我们再举一个稍微复杂的例子,在上例的list中加入一些分隔线
你需要做这些:
- 重(@Override)写 getViewTypeCount() – 返回你有多少个不同的布局
- 重写 getItemViewType(int) – 由position返回view type id
- 根据view item的类型,在getView中创建正确的convertView
以下是代码:
public class MultipleItemsList extends ListActivity { private MyCustomAdapter mAdapter; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mAdapter = new MyCustomAdapter(); for (int i = 1; i < 50; i++) { mAdapter.addItem("item " + i); if (i % 4 == 0) { mAdapter.addSeparatorItem("separator " + i); } } setListAdapter(mAdapter); } private class MyCustomAdapter extends BaseAdapter { private static final int TYPE_ITEM = 0; private static final int TYPE_SEPARATOR = 1; private static final int TYPE_MAX_COUNT = TYPE_SEPARATOR + 1; private ArrayList mData = new ArrayList(); private LayoutInflater mInflater; private TreeSet mSeparatorsSet = new TreeSet(); public MyCustomAdapter() { mInflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE); } public void addItem(final String item) { mData.add(item); notifyDataSetChanged(); } public void addSeparatorItem(final String item) { mData.add(item); // save separator position mSeparatorsSet.add(mData.size() - 1); notifyDataSetChanged(); } @Override public int getItemViewType(int position) { return mSeparatorsSet.contains(position) ? TYPE_SEPARATOR : TYPE_ITEM; } @Override public int getViewTypeCount() { return TYPE_MAX_COUNT; } @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) { ViewHolder holder = null; int type = getItemViewType(position); System.out.println("getView " + position + " " + convertView + " type = " + type); if (convertView == null) { holder = new ViewHolder(); switch (type) { case TYPE_ITEM: convertView = mInflater.inflate(R.layout.item1, null); holder.textView = (TextView)convertView.findViewById(R.id.text); break; case TYPE_SEPARATOR: convertView = mInflater.inflate(R.layout.item2, null); holder.textView = (TextView)convertView.findViewById(R.id.textSeparator); break; } convertView.setTag(holder); } else { holder = (ViewHolder)convertView.getTag(); } holder.textView.setText(mData.get(position)); return convertView; } } public static class ViewHolder { public TextView textView; } }