Question

I have created a Custom preference which has the following constructor

public CoordinatesPreference(Context context, AttributeSet attrs)
{
    super(context, attrs);
    setLayoutResource(R.layout.coordinates_preference);
}

And I have Overriden onCreateView() so it writes to the log like this:

@Override
protected View onCreateView(ViewGroup parent)
{
    Log.d("test", "Creating Preference view");
    return super.onCreateView(parent);
}

and my log is full of "Creating Preference view" messages, this creates a laggy feel to scrolling and I believe convert view is supposed to solve this, I had a look at the preference source code and if convert view is null then onCreateView() is called.

for testing purposes I added this method:

@Override
public View getView(View convertView, ViewGroup parent)
{
    if (convertView == null)
    {
        return super.getView(convertView, parent);
    }
    return super.getView(convertView, parent);
}

and set a break point. I have found that almost always my convert view is null. and therefore it must create a new view, why is this? and how can I improve this to avoid a laggy preference screen?

EDIT: Changed the way the onCreate is called, now its all android I just use setLayoutResource. but this does not solve the problem…

EDIT2: I have used Debug.StartMethodTracing() and have found as I suspected that 55% of the time spend (when I’m just scrolling up and down) is spend on the Inflation of the preference from the method onCreateView() which is called from getView() when convertView is null.

Thanks, Jason

Answer 1

I was running into this problem and I tracked it down to the fact that I had the layout set both in the preferences.xml file and in my Preference subclass onCreateView() method. When I removed the layout from preferences.xml, onCreateView() stopped getting called multiple times.