How can I change Action Bar actions dynamically?

Question

I have an Activity with ActionBar and tab navigation. I am using the split mode, so the tabs are at the top and actions are in the bottom bar. How can I dynamically change the bottom actions? I need this because every tab has different actions.

Blakley

Answer 1

Since the actions are populated by the activity's options menu you can use Activity#invalidateOptionsMenu(). This will dump the current menu and call your activity's onCreateOptionsMenu/onPrepareOptionsMenu methods again to rebuild it.

If you're using action bar tabs to change your fragment configuration there's a better way. Have each fragment manage its own portion of the menu. These fragments should call setHasOptionsMenu(true). When fragments that have options menu items are added or removed the system will automatically invalidate the options menu and call to each fragment's onCreateOptionsMenu/onPrepareOptionsMenu methods in addition to the activity's. This way each fragment can manage its own items and you don't need to worry about performing menu switching by hand.

Disregard

Just a note: setHasOptionsMenu() should be called in onCreate according to the documentation. – Lozoya

That's not actually a requirement. It may be called from there and it is a good place to do so in many circumstances, but if the fragment has already been added and is not hidden the activity's options menu will be invalidated and the new state will be reflected. – Disregard

I agree with you, however the documents don't make it sound like that. "In order for this method to receive calls, however, you must call setHasOptionsMenu() during onCreate() ...". I think they mean you must call setHasOptionsMenu() but they unintentionally made it sound like during onCreate() was also a requirement. – Lozoya

Calling setHasOptionsMenu doesn't work if you've already called it once with true and want to update them. At least this fails with the Android Support Library v4. In that case, use getActivity().supportInvalidateOptionsMenu() which is what setHasOptionsMenu does internally, anyway. – Reflector

That's correct. Invalidating the options menu is the way to go if something has changed. – Disregard

calling invalidateOptionsMenu()does not invoke onPrepareOptionsMenu when called from a menu action, see @AlikElzin-kilaka comment : call ActionMode.invalidate() instead – Refuge

Answer 2

Activity.invalidateOptionsMenu() requires API Level 11. There is a simpler solution which is backwards compatible:

Add the MenuItem to the Menu initially but set its visibility to false. Set visibility to true when desired, using MenuItem.setVisible()

Occultism

Thanks. Just in case helps others... Put MenuItem refreshItem = menu.findItem(R.id.action_refresh); refreshItem.setVisible(false); in your onCreateOptionsMenu – Simmon

@Simmon or "android:visible"="false" in xml – Cession

Answer 3

ActionMode.invalidate() did the trick. It caused the onPrepareActionMode() to be invoked again.

Activity#invalidateOptionsMenu() did not cause the onPrepareActionMode() to be invoked when using list items with multi-select.

Lang

how do I get actionmode? I only have ActionBar – Hectoliter

The ActionMode is the first parameter in onPrepareActionMode(...): goo.gl/tMyBx – Lang

I have never heard of onPrepareAction – Diadromous

@Diadromous - I answered the the action mode way, meaning CAB - Contextual Action Bar. It's when acting on selected list items, thus changing the list of actions. – Lang

Answer 4

Activity.invalidateOptionsMenu() requires API Level 11. Use the Support library version of it supportInvalidateOptionsMenu().

AppCompatActivity activity = (AppCompatActivity) getActivity();
activity.supportInvalidateOptionsMenu();

Erbes