This piece of code:

mUploadMessage.OnReceiveValue(new Uri[] { result });

results in: Error CS0029 Cannot implicitly convert type 'Android.Net.Uri' to 'System.Uri'

in Visual Studio 2022, using Android.Net and Xamarin.

I have attempted to do type conversion, such as:

mUploadMessage.OnReceiveValue(new Uri[] { (Uri)result });

then I get the error: Error CS0030 Cannot convert type 'Android.Net.Uri' to 'System.Uri'

I also attempted:

mUploadMessage.OnReceiveValue(new Uri[] { result as Uri });

but, then the error is: Error CS0039 Cannot convert type 'Android.Net.Uri' to 'System.Uri' via a reference conversion, boxing conversion, unboxing conversion, wrapping conversion, or null type conversion

So, I attempted a longer conversion:

Android.Net.Uri result = intent.Data;
String urlResult = result.ToString();
Uri sysUrl = new System.Uri(urlResult);
mUploadMessage.OnReceiveValue(new Uri[] { sysUrl });

but, then the error generated is: Error CS1503 Argument 1: cannot convert from 'System.Uri[]' to 'Java.Lang.Object?'

Next, I attempted this:

Android.Net.Uri result = intent.Data;
String urlResult = result.ToString();
mUploadMessage.OnReceiveValue(urlResult);

which compiles without an error, but then on executing the functionality I get: Java.Lang.ClassCastException Message=java.lang.String cannot be cast to android.net.Uri[]

Finally, I attempted this:

Android.Net.Uri result = intent.Data;
mUploadMessage.OnReceiveValue(result);

which resulted in: Java.Lang.ClassCastException Message=android.net.Uri$HierarchicalUri cannot be cast to android.net.Uri[]

The original routine is:

protected override void OnActivityResult(int requestCode, Result resultCode, Intent intent)
{
    if (requestCode == FILECHOOSER_RESULTCODE)
    {
        if (null == mUploadMessage) return;
        Android.Net.Uri result = intent.Data;
        mUploadMessage.OnReceiveValue(new Uri[] { result });
        mUploadMessage = null;
    }
}

Here is the code from MainActivity.cs:

using System;

using Android.App;
using Android.Content.PM;
using Android.Runtime;
using Android.OS;
using Android.Webkit;
using Xamarin.Forms.Platform.Android;
using Android.Content;
using System.ComponentModel.Design;

namespace myapp.Droid
{
    [Activity(Label = "myapp", Icon = "@mipmap/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize)]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        public static IValueCallback mUploadMessage; 
        public static int FILECHOOSER_RESULTCODE = 1; 
        public static IValueCallback mUMA; 
        public static int FCR = 1; 
        public static IValueCallback mUploadCallbackAboveL; 
        public static int PHOTO_REQUEST = 10023; 
        public static Uri imageUri; 
        public static MainActivity Instance;
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);

            WebView webview = new WebView(this);
            SetContentView(webview);
            webview.Settings.UseWideViewPort = true;
            webview.Settings.LoadWithOverviewMode = true;
            webview.Settings.DefaultTextEncodingName = "UTF-8";
            webview.Settings.JavaScriptEnabled = true;
            webview.Settings.DomStorageEnabled = true;
            webview.Settings.AllowFileAccessFromFileURLs = true;
            webview.Settings.JavaScriptCanOpenWindowsAutomatically = true;
            webview.Settings.AllowUniversalAccessFromFileURLs = true;
            webview.Settings.AllowContentAccess = true;
            webview.Settings.AllowFileAccess = true;
            webview.SetWebViewClient(new OverWebView(this));
            webview.SetWebChromeClient(new myWebChromeClient(this));
            webview.LoadUrl("https://mywebapp.net");

        }
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }

        public class OverWebView : WebViewClient
        {
            // For API level 24 and later
            public override bool ShouldOverrideUrlLoading(WebView view, IWebResourceRequest request)
            {
                view.Settings.JavaScriptEnabled = true;
                view.Settings.DomStorageEnabled = true;
                view.Settings.AllowFileAccessFromFileURLs = true;
                view.Settings.JavaScriptCanOpenWindowsAutomatically = true;
                view.LoadUrl(request.Url.ToString());
                return false;
            }
            private MainActivity mainActivity;
            public OverWebView(MainActivity mainActivity)
            {
                this.mainActivity = mainActivity;
            }
        }

        public class myWebChromeClient : WebChromeClient
        {
            Activity mActivity = null; 
            public myWebChromeClient(Activity activity) 
            { 
                mActivity = activity; 
            }
            public override bool OnShowFileChooser(WebView webView, IValueCallback filePathCallback, FileChooserParams fileChooserParams)
            {
                MainActivity.mUploadMessage = filePathCallback; 
                PhotoUtils.openFileChooseProcess(mActivity); 
                return true;
            }

        }

        public class PhotoUtils
        {
            private static string TAG = "PhotoUtils";

            public static void openFileChooseProcess(Activity activity)
            {
                Intent i = new Intent(Intent.ActionGetContent);
                i.AddCategory(Intent.CategoryOpenable);
                i.SetType("image/*");
                activity.StartActivityForResult(Intent.CreateChooser(i, "UploadImage"), MainActivity.FILECHOOSER_RESULTCODE);
            }
        }

        protected override void OnActivityResult(int requestCode, Result resultCode, Intent intent)
        {
            if (requestCode == FILECHOOSER_RESULTCODE)
            {
                if (null == mUploadMessage) return;
                Android.Net.Uri result = intent.Data;
                mUploadMessage.OnReceiveValue(result);
                mUploadMessage = null;
            }
        }
    }
}

CodePudding user response：

As the error messages tell you, your attempts to refer to class Uri are being compiled as System.Uri. That's not what you need.

You need Android.Net.Uri.

Simplest fix is to specify WHICH NAMESPACE you want Uri in:

mUploadMessage.OnReceiveValue(new Android.Net.Uri[] { result });

An alternative fix is to make a using that declares this:

using Uri = Android.Net.Uri;