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How to get view from main Activity

There is a class inheritor from the handler through which I control the graphic button.
To search for this button, I pass in the designer a link to the activation. But I want to pass the view there. How can I get a view from activity?
public class FlActivity : AppCompatActivity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.activity_fl);
toolbar = FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
SetSupportActionBar(toolbar);
SupportActionBar.SetDisplayHomeAsUpEnabled(true);
tabLayout = FindViewById<TabLayout>(Resource.Id.tabLayout);
viewPager = FindViewById<ViewPager>(Resource.Id.viewPager);
fpAdapter = new FpAdapter(SupportFragmentManager, null);
uiHandler = new UiHandler(this, MainLooper);
}
}
public class UiHandler : Handler
{
private Activity activity { get; }
public UiHandler(Activity a, Looper loader) : base(loader)
{
activity = a;
}
public override void HandleMessage(Message msg)
{
activity.FindViewById<ImageButton>(Resource.Id.imageButton1).SetImageResource(msg.Data.GetInt("ID", Resource.Drawable.bt_off));
}
}
If I change private Activity activity { get; } to private View view { get; }, how can I transfer the view from the main activity when creating a handler instance. What to replace this in creating a nadler object?

There are quite several ways to do this :
this.Window.DecorView.RootView;
or
this.Window.DecorView.FindViewById(Android.Resource.Id.Content);
or
this.FindViewById(Android.Resource.Id.Content);
or
this.FindViewById(Android.Resource.Id.Content).RootView;
or
((ViewGroup) this.FindViewById(Android.Resource.Id.Content)).GetChildAt(0);
Although, since it's probably a layout, not a single view, I recommend using ViewGroup instead of View (these methods returns View so you have to cast them to ViewGroup if you want)
=================
Credit to this answer

MVVMCross After navigating to fragment the layout is not refreshed

I have a tabbed application that uses MvxTabsFragmentActivity.
When I navigate between tabs, there is the correct behaviour but the first time when I try to navigate inside a fragment, the called fragment is not replaced.
I tried to use both IMvxNavigationService and also the classic method, using ShowViewModel but they both act the same.
I also used a custom presenter for showing the fragments, but with or without it, the problem stills the same.
There is the image with the printscreen
https://imgur.com/a/cfRWlsl
The red highlighted is the fragment where I am navigating to and the black one is the previous fragment.
This is the View that has the button needed for navigation:
public class TrackView : MvxFragment<TrackViewModel>
{
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
base.OnCreateView(inflater, container, savedInstanceState);
var view = this.BindingInflate(Resource.Layout.track_layout, null);
var nextButton = view.FindViewById<Button>(Resource.Id.navigate);
var set = this.CreateBindingSet<TrackView, TrackViewModel>();
set.Bind(nextButton).To(vm => vm.NavigateEventCommand);
set.Apply();
return view;
}
}
This is its ViewModel:
public class TrackViewModel : MvxViewModel
{
private readonly IMvxNavigationService _navigationService;
public TrackViewModel(IMvxNavigationService navigationService)
{
this._navigationService = navigationService;
}
public IMvxCommand NavigateEventCommand => new MvxAsyncCommand(NavigateCommand);
private async Task NavigateCommand()
{
await _navigationService.Navigate<RegistrationViewModel>();
}
}
This is the View where I am navigating to:
public class RegistrationView : MvxFragment
{
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
base.OnCreateView(inflater, container, savedInstanceState);
var view = this.BindingInflate(Resource.Layout.registration_layout, null);
//var set = this.CreateBindingSet<RegistrationView, RegistrationViewModel>();
//set.Apply();
return view;
}
}
This is its ViewModel:
public class RegistrationViewModel : MvxViewModel
{
}
I have also a tabbed Application that uses MvxTabsFragmentActivity, and I am creating the tabs like this:
protected override void AddTabs(Bundle args)
{
this.AddTab<TrackView>(
args,
Mvx.IocConstruct<TrackViewModel>(),
this.CreateTabFor("0", Resource.Drawable.ic_track, "Track"));
this.AddTab<SendView>(
args,
new SendViewModel(),
this.CreateTabFor("1", Resource.Drawable.ic_send, "Send"));
this.AddTab<ProfileView>(
args,
new ProfileViewModel(),
this.CreateTabFor("2", Resource.Drawable.ic_profile, "Profile"));
this.AddTab<MoreView>(
args,
new MoreViewModel(),
this.CreateTabFor("3", Resource.Drawable.ic_more, "More"));
}
I have a custom presenter that is registered this way in the main class:
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
this.tabHost = this.FindViewById<TabHost>(Android.Resource.Id.TabHost);
presenter = (DroidPresenter)Mvx.Resolve<IMvxAndroidViewPresenter>();
var initialFragment = new TrackView() { ViewModel = Mvx.IocConstruct<TrackViewModel>() };
presenter.RegisterFragmentManager(FragmentManager, initialFragment);
}
As I said, with or without the presenter, there is the same behaviour.
I am using MvvmCross 5.7.

RecyclerView not showing - Xamarin .Droid

To me, it seems there's nothing wrong in my code but my recyclerView is not showing up. Please look into my code if the adapter is well set up. Thank you. Please what am i missing in my adapter? The page appears empty although i see that the datasnapShot in my adapter runs but my recyclerView doesn't show.
Adapter
public class PhotoHolder : RecyclerView.ViewHolder
{
public ImageView ImgPhotos;
public PhotoHolder(View itemView):base(itemView)
{
ImgPhotos = (ImageView)itemView.FindViewById(Resource.Id.imageView);
}
public class PhotoAdapter : RecyclerView.Adapter, IValueEventListener
{
public PhotoAdapter(List<Photos> Photos, Context mContext)
{
this.Photos = Photos;
this.mContext = mContext;
photos = (PhotosActivity)mContext;
mDatabaseImage = FirebaseDatabase.Instance.Reference.Child("Photos");
mDatabaseImage.AddValueEventListener(this);
}
public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
{
hold = holder as PhotoHolder;
hold.ImgPhotos.SetImageResource(Resource.Drawable.cheese_5);
}
public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
{
View v = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.list_photos, parent, false);
PhotoHolder holder = new PhotoHolder(v);
return holder;
}
public override int ItemCount
{
get { return Photos.Count; }
}
public void OnCancelled(DatabaseError error)
{
throw new NotImplementedException();
}
public void OnDataChange(DataSnapshot snapshot)
{
var items = snapshot.Children?.ToEnumerable<DataSnapshot>();
foreach (DataSnapshot item in items)
{
map = (HashMap)item.Value;
imageUrl = new FilePhotos(map.Get("URL").ToString());
}
}
}
}
PhotoActivity
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
FrameLayout content = (FrameLayout)FindViewById(Resource.Id.content_frame);
LayoutInflater.Inflate(Resource.Layout.PhotoView, content);
adapter = new PhotoAdapter(Photos, this);
rv = FindViewById<RecyclerView>(Resource.Id.recyclerView);
rv.SetLayoutManager(new LinearLayoutManager(this));
rv.SetItemAnimator(new DefaultItemAnimator());
rv.SetAdapter(adapter);
adapter.NotifyDataSetChanged();
}

How to pass data between tabs on Xamarin Android?

I have two tabs in viewpager. So in fragment1 I input a text and when in tab2 is selected and then fragment2 will get data from that text from fragment1.
ex: when I open tab1 -> I input a text is "abcd" -> I open tab2 -> I want to get a text is "abcd" from tab1(fragment1).
public class Fragment1 : Android.Support.V4.App.Fragment
{
Fragment2 frag2 = new Fragment2();
public override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Create your fragment here
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
// Use this to return your custom view for this Fragment
// return inflater.Inflate(Resource.Layout.YourFragment, container, false);
Singleton singleton = Singleton.GetInstance();;
singleton.SetSource("abcd");
}
}public class Singleton
{
private static Singleton singleton;
string a = null;
private Singleton()
{
}
public static Singleton GetInstance()
{
if (singleton == null)
singleton = new Singleton();
return singleton;
}
public void SetSource(string text)
{
this.a = text;
}
public string showMessage()
{
return a;
}
}
public class Fragment2 : Android.Support.V4.App.Fragment
{
public List<string> data = new List<string>();
public void add(string t)
{
data.Add(t);
}
TextView txt;
public override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Create your fragment here
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
// Use this to return your custom view for this Fragment
// return inflater.Inflate(Resource.Layout.YourFragment, container, false);
//return base.OnCreateView(inflater, container, savedInstanceState);
return inflater.Inflate(Resource.Layout.view2, container, false);
txt = View.FindViewById<TextView>(Resource.Id.txtgetdata);
if (data != null)
{
txt.Text = data[0];
}
else
Toast.MakeText(Application.Context, "no", ToastLength.Long).Show();
}
}
I have tried it but don't having the result.

After a few hours of research/test & debugging and solved, try this out.
In your Activity
add public string tabFragment { get; set; }
In your source fragment
ie on click or that navigate to other fragment
string tab = ((ActivityUser)Activity).tabFragmentAddUser;
FragmentAddUser fragment = (FragmentAddUser);
Activity.SupportFragmentManager.FindFragmentByTag(tab);
fragment.setValText("Hello");
viewPager.SetCurrentItem(1, true);
In your destination fragment (ie which elements will be modified)
add a method like this
public void setValText(string str) { txtUsrFirstName.Text = str; }
==================================================================

Fragment fragment = new Fragment();
Bundle bundle = new Bundle();
bundle.putInt(key, value);
fragment.SetArguments(bundle);
in on create of the other fragment
Bundle bundle = this.GetArguments();
int myInt = bundle.GetInt(key, defaultValue);
optionaly two fragments should never communicate directly and should communicate through activity
From Developers website:
Often you will want one Fragment to communicate with another, for
example to change the content based on a user event. All
Fragment-to-Fragment communication is done through the associated
Activity. Two Fragments should never communicate directly.
refer this and this

Loading Resource View in Fragment with ActionBar tabs

I don't know why it is not working but what am I doing wrong. It works fine if I explicitly set the TextView and not using Inflate method by the LayoutInflater. It just closes my application when I run it and when I switch to Test tab it'll just crash with no errors in the output window.
public class MyProfileActivity : Activity
{
protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
ActionBar actionBar = ActionBar;
actionBar.NavigationMode = ActionBarNavigationMode.Tabs;
actionBar.SetDisplayShowTitleEnabled (false);
ActionBar.Tab tab = actionBar.NewTab ();
tab.SetText ("Home");
// tab.SetIcon (Resource.Drawable.tab_home);
tab.SetTabListener(new TabListener<HomeFragment>(this, "home"));
actionBar.AddTab (tab);
tab = actionBar.NewTab ();
tab.SetText("Terms");
// tab.SetIcon(Resource.Drawable.tab_terms);
tab.SetTabListener (new TabListener<TermsFragment> (this, "terms"));
actionBar.AddTab (tab);
tab = actionBar.NewTab();
tab.SetText("test");
// tab.SetIcon(Resource.Drawable.tab_terms);
tab.SetTabListener(new TabListener<TestFragment>(this, "test"));
actionBar.AddTab(tab);
}
}
Fragments
public class TestFragment : Fragment
{
private View _fragmentView;
public override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Create your fragment here
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
_fragmentView = inflater.Inflate(Resource.Layout.Tabs, container);
return _fragmentView;
}
}
#region HomeFragment
public class HomeFragment : Fragment
{
public HomeFragment() : base() {}
public override View OnCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
TextView tv = new TextView (Activity);
tv.Text = "Home";
return tv;
}
}
#endregion
#region TermsFragment
public class TermsFragment : Fragment
{
public TermsFragment() : base() {}
public override View OnCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
TextView tv = new TextView (Activity);
tv.Text = "Terms";
return tv;
}
}
#endregion
TabListener
public class TabListener<T> : Java.Lang.Object, ActionBar.ITabListener where T : Fragment
{
#region Members
private Fragment m_fragment;
private readonly Activity m_activity;
private readonly string m_tag;
private readonly T m_fragmentType;
#endregion
#region Constructor
public TabListener(Activity activity, String tag)
{
// The Activity is our host Activity and provides the Context.
// The type T and the tag will be used to instantiate the fragment.
// m_fragment will hold the instance for reuse after it is first created.
m_activity = activity;
m_tag = tag;
}
#endregion
#region ITabListener implementation
public void OnTabSelected(ActionBar.Tab tab, FragmentTransaction ft)
{
// Instantiate the reference and add it to the container,
// or attach it if it has already been created
if (m_fragment == null)
{
m_fragment = Fragment.Instantiate(m_activity, Java.Lang.Class.FromType(typeof(T)).Name);
ft.Add(global::Android.Resource.Id.Content, m_fragment, m_tag);
}
else
{
ft.Show(m_fragment);
}
}
public void OnTabUnselected(ActionBar.Tab tab, FragmentTransaction ft)
{
if (m_fragment != null)
{
ft.Hide(m_fragment);
}
}
public void OnTabReselected(ActionBar.Tab tab, FragmentTransaction ft)
{
// User selected the already selected tab. Usually do nothing.
}
#endregion
public class TestFragment : Fragment
{
private View _fragmentView;
public override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Create your fragment here
}
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
_fragmentView = inflater.Inflate(Resource.Layout.Tabs, container);
return _fragmentView;
}
}
}

I tried using with your code and got java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first. when navigating to TestFragment.
This answer allowed me to fix the problem by providing false for parameter attachToRoot:
_fragmentView = inflater.Inflate(Resource.Layout.TestLayout, container, false);