Change value in a list during runtime

Question

Hello everyone,

 

I have a button and a list displayed. When clicking on the button, I want to change the value of a specific item within that list. Please see following aimed output example:

 

[Program Start]

 

Item Name	Value
Item Number 1	Original Value
Item Number 2	Original Value
Item Number 3	Original Value

 

 [Button Click]

 

Item Name	Value
Item Number 1	Original Value
Item Number 2	Changed Value
Item Number 3	Original Value

 

So how can I do this? What does my `private void OnButtonClick(object sender, EventArgs e)` have to look like? How can I access a specific entry in that list?

 

 To be better able to help me, I will share my code following:

public class MyActivity : Activity
{
    List List = null;

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        SetContentView(Resource.Layout.MyActivity);

        List = PopulateList();
        var lv = FindViewById(Resource.Id.list);
        var adapter = new ListAdapter(this, Resource.Layout.List, List);
        lv.Adapter = adapter;

        FindViewById(Resource.Id.button).Click += OnButtonClick;
    }
}

class ListAdapter : ArrayAdapter
{
    List List;
    public ListAdapter(Context Context, int ListId, List List) : base(Context, ListId, List)
    {
        this.List = List;
    }
    public override int Count
    {
        get { return List.Count; }
    }
    public override View GetView(int position, View convertView, ViewGroup parent)
    {
        View v = convertView;
        if (v == null)
        {
            LayoutInflater inflater = (LayoutInflater)Context.GetSystemService(Context.LayoutInflaterService);
            v = inflater.Inflate(Resource.Layout.List, parent, false);
        }
        v.FindViewById(Resource.Id.name).Text = List[position].Name;
        v.FindViewById(Resource.Id.value).Text = "Original Value";
        return v;
    }
}

 Using following *.axml-files:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android        ="http://schemas.android.com/apk/res/android"
android:orientation  ="vertical"
android:layout_width ="match_parent"
android:layout_height="match_parent">
<Button
    android:layout_width ="match_parent"
    android:layout_height="wrap_content"
    android:text="Click Me"
    android:id="@+id/button" />
<ListView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/list" />
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
<TextView
        android:id="@+id/value"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</RelativeLayout>

 When simply doing

private void OnButtonClick(object sender, EventArgs e)
{
   FindViewById(Resource.Id.value).Text = "Changed Value";
}

 only the first item changes. So how to pass the position through the adapter? Can anyone maybe help?

 

Thanks in advance, 

 

Best regards

 

Edit: I found out that I have to do `adapter.NotifyDataSetChanged();` somewhere in the end. But when adding this, unfortunately nothing happens anymore when clicking the button.