Fix for Android's ActionBar, where navigational tabs don't work if the tabs are reduced to a dropdown (Spinner). This version is designed to work with Action Bar Sherlock. Based on the original discussion here: http://stackoverflow.com/questions/15409330/action-bar-selecttab-and-setselectednavigationitem-not-working

ActionBarNavigationFixABS.java

    public void onPageSelected(int position) {
        // When swiping between different app sections, select the corresponding tab.
        // We can also use ActionBar.Tab#select() to do this if we have a reference to the
        // Tab.
        actionBar.setSelectedNavigationItem(position);
        

        /*
         * 
         * When paging between tabs, normally the dropdown list (spinnerAdapter) won't change properly.  This
         * occurs on small devices in landscape mode, i.e. when the tab labels are reduced to a dropdown to save space.
         * 
         * Thanks to this StackOverflow discussion for figuring out how to solve this problem:
         * http://stackoverflow.com/questions/15409330/action-bar-selecttab-and-setselectednavigationitem-not-working
         */
        
        try {
            //now use reflection to select the correct Spinner if
            // the bar's tabs have been reduced to a Spinner
            Activity activity = getActivity();
            int actionBarResId = getResources().getIdentifier("action_bar", "id", "android");
            if (actionBarResId == 0) { // not found, use action bar sherlock
                actionBarResId = com.actionbarsherlock.R.id.abs__action_bar;
            }
            View action_bar_view = activity.findViewById(actionBarResId);
            Class<?> action_bar_class = action_bar_view.getClass();
            Field tab_scroll_view_prop = action_bar_class.getDeclaredField("mTabScrollView");
            tab_scroll_view_prop.setAccessible(true);
            //get the value of mTabScrollView in our action bar
            Object tab_scroll_view = tab_scroll_view_prop.get(action_bar_view);
            if (tab_scroll_view == null) return;
            Field spinner_prop = tab_scroll_view.getClass().getDeclaredField("mTabSpinner");
            spinner_prop.setAccessible(true);
            //get the value of mTabSpinner in our scroll view
            Object tab_spinner = spinner_prop.get(tab_scroll_view);
            if (tab_spinner == null) return;
            Method set_selection_method = tab_spinner.getClass().getSuperclass().getDeclaredMethod("setSelection", Integer.TYPE, Boolean.TYPE);
            set_selection_method.invoke(tab_spinner, position, true);
        
        } catch (NoSuchFieldException ignore) {
            
        } catch (InvocationTargetException ignore) {
            
        } catch (IllegalAccessException ignore) {
            
        } catch (NoSuchMethodException ignore) {
            
        }
    }