_adapater 在当前上下文中不存在

Question

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

        // Set our view from the "main" layout resource
        SetContentView (Resource.Layout.Main);
        var product = new[] {

            "India","Nokia","Dhurv","Gohil","Patel","Sony","Bhaumik","Umang","Riya","Afghanistan","America"

        };


        var _listView = FindViewById<ListView>(Resource.Id.MylistView);
        var _adapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleListItem1, product);
        _listView.Adapter = _adapter;

    }


    public override bool OnCreateOptionsMenu (IMenu menu) 
    {
        MenuInflater.Inflate (Resource.Layout.Menu,menu);



        var item = menu.FindItem(Resource.Id.action_search);
        var searchView = MenuItemCompat.GetActionView (item);

        var _searchView = searchView.JavaCast<SearchView>();

        _searchView.QueryTextChange += (s, e) => _adapter.Filter.InvokeFilter(e.NewText);


        _searchView.QueryTextSubmit += (s, e) =>
        {
            // Handle enter/search button on keyboard here
            Toast.MakeText(this, "Searched for: " + e.Query, ToastLength.Short).Show();
            e.Handled = true;
        };


        return true;
    }

我收到错误：

_adapter does not exist in current context (in OnCreateOptionsMenu)

如何解决这个错误？

我没有使用 AppCompat 作为 SearchView。代码可以吗？有办法解决这个问题吗？

Answer 1

您无法在 OnCreateOptionsMenu 中访问 _adapter，因为它仅在 OnCreate 中已知。要在 class 的其他方法中访问它，您需要将其设为 class 成员。也许有点像这样：

class MyClass
{
    ArrayAdapter<String> _adapter = null;
    ...
    protected override void OnCreate (Bundle bundle)
    {
        base.OnCreate (bundle);
        // ... the rest of your code
        _adapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleListItem1, product);
        // ...
    }

    protected override void OnCreateOptionsMenu(IMenu menu)
    {
        // ... other stuff
        _searchView.QueryTextChange += (s, e) => _adapter.Filter.InvokeFilter(e.NewText);
        // ...
    }
}

注意OnCreate中_adapter = ...前面没有var。

_adapater 在当前上下文中不存在

_adapater does not exist in the current context

android

searchview

xamarin