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 view, int id) {
        SparseArray<View> viewHolder = (SparseArray<View>) view.getTag();
        if (viewHolder == null ) {
            viewHolder = new SparseArray<View>();
            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;
}