How to implement OnClickListener of ListView items for good performance (avoiding slow scrolling) - android-listview

Question

I've been reading about ViewHolder Pattern and it's effects on ListView scrolling performance lately.
For a smooth scrolling, fast ListView should i avoid using OnClickListener registerations inside adapter getView() method such as:
#Override
public View getView(final int position, View convertView, ViewGroup parent)
{
ViewHolder holder;
if (convertView == null)
{
holder = new ViewHolder();
LayoutInflater vi = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(mResourceId, null);
holder.btn1 = (TextView) convertView.findViewById(R.id.btn1);
holder.img1 = (TextView) convertView.findViewById(R.id.img1);
convertView.setTag(holder);
} else { holder = (ViewHolder) convertView.getTag(); }
final Items item = getItem(position);
holder.btn1.setText(item.btnText);
holder.img1.setBackgroundResource(item.imgSource);
holder.img1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) { /* .. my code block USING POSITION ARG .. */ }
}
holder.btn1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) { /* .. My Code Block USING POSITION ARG .. */ }
}
return convertView;
}
If so, is registering a OnItemClickListener to ListView instance as following sample does a good practice:
myListView.setOnItemClickListener(new OnItemClickListener()
{
#Override
public void onItemClick(AdapterView<?> arg0, View view, int position, long id) {
if (view.getId() == R.id.btn1)
{
// my code block USING POSITION ARG
}
else if (view.getId() == R.id.img1)
{
// my code block USING POSITION ARG
}
}
});

Answer 1

It's better to use a Wrapper to access to your View and to define your OnClickListener earlier (and outside the adapter for a better usability).
The following sample show how to handle 2 clickable View on one single item of the ListView with good performance:
public class ItemAdapter extends BaseAdapter {
private List<Item> items;
private ItemWrapper wrapper = null;
private OnClickListener onMyItemClickListener1;
private OnClickListener onMyItemClickListener2;
public ItemAdapter(Context context, List<Item> items, OnClickListener onMyItemClickListener1, OnClickListener onMyItemClickListener2) {
this.inflater = LayoutInflater.from(context);
this.items = items;
this.onMyItemClickListener1 = onMyItemClickListener1;
this.onMyItemClickListener2 = onMyItemClickListener2;
}
#Override
public int getCount() {
return items.size();
}
#Override
public Object getItem(int position) {
return items.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public synchronized View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
if (row == null) {
row = inflater.inflate( R.layout.item, null);
wrapper = new ItemWrapper(row);
row.setTag(wrapper);
} else {
wrapper = (ItemWrapper)row.getTag();
}
Item item = getItem(position);
wrapper.getClickView1().setOnClickListener(onMyItemClickListener1);
wrapper.getClickView2().setOnClickListener(onMyItemClickListener2);
return(row);
}
}
public class ItemWrapper {
private View baseView;
private View clickView1;
private View clickView2;
public ItemWrapper(View baseView) {
this.baseView = baseView;
}
public View getClickView1() {
if ( clickView1 == null) {
clickView1 = (View)baseView.findViewById(R.id.clickView1);
}
return(clickView1);
}
public View getClickView2() {
if ( clickView2 == null) {
clickView2 = (View)baseView.findViewById(R.id.clickView2);
}
return(clickView2);
}
}