Adapter的getViewTypeCount和getItemViewType

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:

1. 重(@Override)写 getViewTypeCount() – 返回你有多少个不同的布局
2. 重写 getItemViewType(int) – 由position返回view type id
3. 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;
    }
}

运行程序，你会看到每4个item一个分割线：