Question

Usually an Adapter will have this to optimize the performance of the listview:

 @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            System.out.println("getView " + position + " " + convertView);
            ViewHolder holder = null;
            if (convertView == null) {
                convertView = mInflater.inflate(R.layout.item1, null);
                holder = new ViewHolder();
                holder.textView = (TextView)convertView.findViewById(R.id.text);
                convertView.setTag(holder);
            } else {
                holder = (ViewHolder)convertView.getTag();
            }
            holder.textView.setText(mData.get(position));
            return convertView;
        }

and view holder is:

public static class ViewHolder {
    public TextView textView;
}

But what if i have different type of rows, like 1 with an ImabeView, 1 with a CheckBox, 1 with EditText

1st thing will be:

@Override
public int getViewTypeCount() {

    return 3;
}

@Override
public int getItemViewType(int position) {

         //if something
         return 0
         //if something else
         return 1
         //if something different
         return 2
}

and in getView();

getView(int position, View convertView, ViewGroup parent){

    //if convetView == null, getItemViewType(position) and depending on the type inflate respective layout
    convertView.setTag(holder);
   //else
    holder = (ViewHolder)convertView.getTag();
}

But what about the ViewHolders, should i have 3 Different ViewHolders and depending on the type……..setTag for respective Holder?

I could find any example for something like this. Actually i haven’t seen anu ListView using more than 1 ViewHolder.

Am i doing it the right way??

Thank You

Answer 1

There is nothing stopping you from declaring all possible views from all of ListView‘s layouts in a single ViewHolder class(so the ViewHolder will hold a reference to an ImageView, CheckBox and EditText from your example).

In the getView method when the convertView is null you will set the views in the ViewHolder only for that type of row, all other view references in the ViewHolder will be null. When it’s time to use the views from the ViewHolder just see with which type of row your working and only get the views from the ViewHolder that belong to that row.

You could also use three ViewHolder classes for each type of row(and set them for each particular row when you inflate it), but I think the first versions is nicer. In the end you could go either way as long as you properly implement the multiple row types mechanism.