ViewHolder 的一种更简洁写法

public class ViewHolder {

// I added a generic return type to reduce the casting noise in client code

@SuppressWarnings("unchecked")
public static  T get(View view, int id) {
SparseArray viewHolder = (SparseArray) view.getTag();
if (viewHolder == null) {
viewHolder = new SparseArray();
view.setTag(viewHolder);
}

View childView = viewHolder.get(id);
if (childView == null) {
childView = view.findViewById(id);
viewHolder.put(id, childView);
}
return (T) childView;
}
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

if (convertView == null) {
convertView = LayoutInflater.from(context).inflate(R.layout.banana_phone, parent, false);
}

ImageView bananaView = ViewHolder.get(convertView, R.id.banana);
TextView phoneView = ViewHolder.get(convertView, R.id.phone);

BananaPhone bananaPhone = getItem(position);
phoneView.setText(bananaPhone.getPhone());
bananaView.setImageResource(bananaPhone.getBanana());

return convertView;
}