why MenuItemCompat.getActionProvider returns null?

Question

I tried to use android.support.v7.widget.ShareActionProvider on actionbar in my app. So I followed the example from android document but got some issues.
Here\'s my m

Answer 1

the variable: Android.Support.V7.Widget.ShareActionProvider shareActionProvider;

this.MenuInflater.Inflate(Resource.Menu.share_action_provider, menu);
var shareItem = menu.FindItem(Resource.Id.menu_item_share_action_provider_action_bar);
MenuItemCompat.SetShowAsAction (shareItem,  MenuItemCompat.ShowAsActionIfRoom);
var actionprov = new Android.Support.V7.Widget.ShareActionProvider (this);
MenuItemCompat.SetActionProvider (shareItem, actionprov);
var test =  MenuItemCompat.GetActionProvider (shareItem);
shareActionProvider = test.JavaCast<Android.Support.V7.Widget.ShareActionProvider>();
var intent = new Intent(Intent.ActionSend);
intent.SetType("text/plain");
intent.PutExtra(Intent.ExtraText, "ActionBarCompat is Awesome! Support Lib v7 #Xamarin");
shareActionProvider.SetShareIntent (intent);
return base.OnCreateOptionsMenu(menu); 

this did the trick with me... i just created my own shareactionprovider ! and i set it myself, then get it... and maybe theres some code even thats not needed.. but its a lot of casting AND MAKE SURE you use the right ones all the time, if you just type "ShareActionProvider" you are in fact using V4..! instead of V7

Answer 2

In my case it was wrong namespace in menu.xml:

<menu xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto">
  <item android:id="@+id/menu_item_share"
        app:actionProviderClass="android.support.v7.widget.ShareActionProvider"/>

Pay attention to app:actionProviderClass="android.support.v7.widget.ShareActionProvider": it should have

• correct package (android.widget android.support.v7.widget)
• correct namespace (android app).

Unfortunatelly, the compiler compiles it without errors, only Android Studio makes notification with underlining.

Answer 3

For Android Pie the action provider class has changed again:

app:actionProviderClass="androidx.appcompat.widget.ShareActionProvider"

Answer 4

I had the same nullPointer probleme in my app. As @josh527 stated, I forgot to define a custom xml namespace for my application. I know it was not your probleme, but some people may reach your post like me and not see that so I just wanted to spot it ;)

Answer 5

Make sure that your class extends AppCompatActivity instead of just Activity.

Note: Edited to reflect the updated app compat library.

Answer 6

After some reading and that includes probably some of you responses, finally this issued is solved:

1. Share_Menu.xml. Make sure you have a custom namespace and the actionProvider class is from that custom namespace as well as the correct value: android.support.v7.widget.ShareActionProvider

   <menu xmlns:android="http://schemas.android.com/apk/res/android" xmlns:myapp="http://schemas.android.com/apk/res-auto"> <item android:id="@+id/action_share" android:title="@string/action_detail_share" myapp:showAsAction="always" myapp:actionProviderClass="android.support.v7.widget.ShareActionProvider"></item> </menu>

2. Detail_Activity.java
   2.1. Inherit from ActionBarActivity instead of Activity
   2.2. Add the correct imports

   import android.support.v4.app.Fragment; import android.support.v4.view.MenuItemCompat; import android.support.v7.app.ActionBarActivity; import android.support.v7.widget.ShareActionProvider;

3. AndroidManifest.xml Add the android:theme="@style/Theme.AppCompat.Light"

   <activity android:name=".detail_activity" android:label="@string/title_activity_detail_activity" android:theme="@style/Theme.AppCompat.Light" android:parentActivityName=".main_activity" >

4. Build.gradle
   4.1. In my case just to stay in the safe side I turn offf ProGuard in Debug.

   debug { runProguard false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' }

4.2. Make sure that you have the following compile section in dependencies

`compile 'com.android.support:appcompat-v7:20.0.+'`