Xamarin.Android how to auto update RecyclerView

Question

Following this article I created a simple application that displays a list. The list I get from a web service (.asmx web service).

I want to auto update RecyclerView every 5 seconds and I have no idea how to do it.

In WinForms I would have used the Timer component, but I don't know how this works in Xamarin.

MainActivity.cs

[Activity(Label = "CibMonitor", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : AppCompatActivity
    {
        RecyclerView recyclerView;
        RecyclerView.LayoutManager layoutManager;
        ConnectionItemsAdapter adapter;
        ConnectionItem[] connectionItems;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
            SetContentView(Resource.Layout.Main);

            var ci = new ConnectionItem();

            //Get list from web service
            connectionItems = ci.GetList().ToArray();

            //Setup RecyclerView
            adapter = new ConnectionItemsAdapter(this, connectionItems);

            recyclerView = FindViewById<RecyclerView>(Resource.Id.recyclerView);

            recyclerView.SetAdapter(adapter);

            ChangedData();
        }
    }

Update I created new method in activity class as York Shen suggested

void ChangedData()
{
    Task.Delay(5000).ContinueWith(t =>
    {
        var newData = ConnectionItem.GetList();
        adapter.RefreshItems(newData);
        ChangedData();
    }, TaskScheduler.FromCurrentSynchronizationContext());
}

This is my update method in adapter class:

public void RefreshItems(List<ConnectionItem> newItems)
{
    items.Clear();
    items = newItems;
    NotifyDataSetChanged();
}

my app stops working, no exception only this message:

i tried `notifyDataSetChanged()` method in adapter but not worked — Ruslan_K, May 25 '17 at 03:18
[this](https://stackoverflow.com/a/23124493/3373603) handler? can you show how to write this in c#? — Ruslan_K, May 25 '17 at 05:41
alittle googling will do the trick. Trust me, it's easy. Search for `android handler xamarin` — Vladyslav Matviienko, May 25 '17 at 05:43
Sorry for late, it seems that this is a ANR, you can't do too much work in Main thread. Can you share a demo about this? I don't know what you did in the Main thread. — York Shen, Jun 01 '17 at 05:29

York Shen · Accepted Answer · 2017-05-29T15:05:34.933

1

You can create a Task which can help you update recyclerView every 5 seconds:

void ChangedData()
    {
        Task.Delay(5000).ContinueWith(t =>
        {
           adapter.NotifyDataSetChanged();
           ChangedData();//This is for repeate every 5s.
        }, TaskScheduler.FromCurrentSynchronizationContext());
    }

EDIT:

Sorry for late reply, calling the ChangedData() in Task.Delay() can resolve the repeate problem. You can invoke the ChangedData() in OnCreate() method. Hope this can help you. : )

edited May 29 '17 at 15:05

answered May 29 '17 at 07:35

York Shen

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i need to invoke `ChangedData()` method in `OnCreate()` method? – Ruslan_K May 29 '17 at 08:19
ChangedData() executes only once, my app freezed and i get message `Myapp isn't responding do you want to close it` – Ruslan_K May 29 '17 at 08:21
@user3373603, Sorry for late, I had add the solution in my answer. : ) – York Shen May 29 '17 at 08:53

Xamarin.Android how to auto update RecyclerView

1 Answers1