ViewHolder简洁写法

本文参考至：http://www.eoeandroid.com/thread-321547-1-1.html


以前的viewHolder一般的写法是：
        ViewHolder holder = null;
        if(convertView == null){
                convertView = mInflater.inflate(R.layout.xxx null);
                holder = new ViewHolder();
                holder.tvXXX = (TextView)findViewById(R.id.xxx);
                //...一连串的findViewById
        }
        else{
                holder = (ViewHolder) convertView.getTag();  
        }
         
         
         
        private static class ViewHolder{
                TextView tvXXX;
                //很多view的定义
        }

现在可以试着用这种方式：
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;
    }
}

其中getView的写法可以如下
@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;
}