[android] Creating a button in Android Toolbar

Another possibility is to set the app:actionViewClass attribute in your menu:

<menu xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto">
  <item
     android:id="@+id/get_item"
     android:orderInCategory="1"
     android:text="Get"
     app:showAsAction="always" 
     app:actionViewClass="android.support.v7.widget.AppCompatButton"/>
</menu>

In your code you can access this button after the menu was inflated:

public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater menuInflater = getMenuInflater();
    menuInflater.inflate(R.menu.sample, menu);

    MenuItem getItem = menu.findItem(R.id.get_item);
    if (getItem != null) {
        AppCompatButton button = (AppCompatButton) getItem.getActionView();
        //Set a ClickListener, the text, 
        //the background color or something like that
    }

    return super.onCreateOptionsMenu(menu);
}