I am trying to reuse NavigationBar from Android ActionBar to navigate between screens. Since each screen contains a lot of separate logic, I would like to have an Activity for each screen, but each screen should reuse an ActionBar, as it contains navigation and other user views.
To do this, I created a base activity class that generates the corresponding action bar. The following code works as I expect, but something is not quite right. It seems to me that I am working too much on what should be easier. Also, although my underlying activity reuses a lot of code, it actually does not use an ActionBar in memory.
Is there any other native navigation control that I could use to achieve this? I do not want to customize the layout or create a custom navigation bar.
In addition, I am using Xamarin Mono for Android.
Basic Navigation Operation
public abstract class BaseNavigationActivity : Activity { private NavigationScreens[] _availableScreens = { NavigationScreens.Screen1, NavigationScreens.Screen2 }; private NavigationScreens _currentScreen = NavigationScreens.Unknown; protected override void OnCreate(Bundle bundle) { base.OnCreate(bundle);
Activity Example
[Activity(Label = "ActionBarTest", MainLauncher = true, Theme = "@style/CustomActionBarStyle", LaunchMode = LaunchMode.SingleInstance)] public class ActionBarNavigationTestActivity : BaseNavigationActivity { public ActionBarNavigationTestActivity() : base(NavigationScreens.Screen1) { } protected override void OnCreate(Bundle bundle) { base.OnCreate(bundle); SetContentView(Resource.Layout.ActionBarNavigation); } }
Adapters and Listeners
public class ScreenNavigationAdapter : BaseAdapter { private IEnumerable<NavigationScreens> _screens; private LayoutInflater _layoutInflater; public ScreenNavigationAdapter(Context context, IEnumerable<NavigationScreens> screens) { _screens = screens; // Retrieve the layout inflater from the provided context _layoutInflater = LayoutInflater.FromContext(context); } public override Java.Lang.Object GetItem(int position) { return null; } public override long GetItemId(int position) { return position; } public override View GetView(int position, View convertView, ViewGroup parent) { var view = convertView; // Try to reuse views as much as possible. if (view == null) { // inflate a new layout for the view. view = _layoutInflater.Inflate(Resource.Layout.SpinnerViewLayout, parent, false); } TextView textView = view.FindViewById<TextView>(Resource.Id.MenuText); textView.Text = _screens.ElementAt(position).ToString(); return view; } public override int Count { get { return _screens.Count(); } } public NavigationScreens GetScreenAt(int position) { return _screens.ElementAt(position); } } public class ScreenNavigationListener : Java.Lang.Object, ActionBar.IOnNavigationListener { private readonly BaseNavigationActivity _currentActivity = null; private readonly ScreenNavigationAdapter _adapter = null; public ScreenNavigationListener(BaseNavigationActivity currentScreen, ScreenNavigationAdapter adapter) { _currentActivity = currentScreen; _adapter = adapter; } public bool OnNavigationItemSelected(int itemPosition, long itemId) { NavigationScreens selectedScreen = _adapter.GetScreenAt(itemPosition); if (_currentActivity.CurrentScreen == selectedScreen) { // Already displaying the selected screen, dont do anything return true; } Intent intent = null; if (selectedScreen == NavigationScreens.Screen1) { intent = new Intent(_currentActivity, typeof(ActionBarNavigationTestActivity)); } if (selectedScreen == NavigationScreens.Screen2) { intent = new Intent(_currentActivity, typeof(ActionBarNavigationTestActivity2)); } if (intent != null) { intent.SetFlags(ActivityFlags.NoAnimation); _currentActivity.StartActivity(intent); return true; } return false; } } public enum NavigationScreens { Unknown = -1, Screen1 = 0, Screen2 }