What should I pass for root when inflating a layout to use for a MenuItem's ActionView?

dlf picture dlf · May 24, 2014 · Viewed 27k times · Source

I have an ImageView that I attach to a MenuItem as its ActionView (the item appears in the ActionBar). The layout for this view comes from XML. I'm inflating it like so:

ImageView actionView = (ImageView) layoutInflater.inflate(
   R.layout.action_view_layout, null);

This appears to work fine. However; passing null for root in the call to inflate() makes Lint yell at me:

Avoid passing null as the view root (need to resolve layout parameters on the inflated layout's root element)

I can seemingly manage without a root in my specific case, but I'd rather have the code be as correct as possible. The problem is, I'm not sure which View should be used as the root here. This answer says it should be "the widget that is surrounding the view objects that you want to inflate." But what does that mean here? The one for the action bar? The activity? Something else entirely?


Update: Reading the answers has made me suspect me the right thing to do is:

  1. Get the ActionBar View corresponding to the MenuItem
  2. Get its root
  3. Cast the root to a ViewGroup
  4. Pass the result to the inflater

This seems to work. Can anyone confirm or deny whether this is what should be done?

Answer

Damian Petla picture Damian Petla · May 24, 2014

I would simply do it like this:

menuItem.setActionView(R.layout.action_view_layout);

Let Android inflate the view for you.

If you need to do some extra changes on this ImageView call

ImageView imageView = (ImageView) menuItem.getActionView();

Update

In order to cater to your curiosity. That is what folks from Google do under the hood:

public MenuItem setActionView(int resId) {
    final Context context = mMenu.getContext();
    final LayoutInflater inflater = LayoutInflater.from(context);
    setActionView(inflater.inflate(resId, new LinearLayout(context), false));
    return this;
}