viewholder简单写法

public class ViewHolder {// I added a generic return type to reduce the casting noise in client code@SuppressWarnings("unchecked")public static <T extends View> T get(View convertView, int id) {SparseArray<View> viewHolder = (SparseArray<View>) convertView.getTag();if (viewHolder == null) {viewHolder = new SparseArray<View>();convertView.setTag(viewHolder);}View childView = viewHolder.get(id);if (childView == null) {childView = convertView.findViewById(id);viewHolder.put(id, childView);}return (T) childView;}}