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Editorial Team
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Asked: 2026-05-31T11:45:38+00:00

My current monodroid project is having two problems – one in loading from Assets

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My current monodroid project is having two problems – one in loading from Assets and the other is a generated webpage being passed to be displayed and their inter-related which makes things more annoying!

The assets problem is simple enough, the file can’t be found. My current code looks like this

Android.App.Application.SynchronizationContext.Post(delegate
{
    string uri = "file:///android_asset/StyleSheet.css";
    string settings = string.Empty;

    using (var input = c.Assets.Open(uri))
    using (StreamReader sr = new System.IO.StreamReader(input))
    {
         settings = sr.ReadToEnd();
    }

    string CSS = "<html><head><style>" + settings + "</style></head><body style='height:600px;background: url(Back-AQHA.jpg)' >";
    retStr = CSS + tableData.Content + "</body></html>";
    callback(retStr);
}, null);

This dies at the sr.ReadToEnd() line as the file can’t be found. All the permissions are correctly set for me to be able to access the assets directory and read in.

c is just a Context passed to the method

Now, assuming that the file had be read in and passed back to the caller, it now fails to be displayed (tested this by generating a page within the app and passing it back)… The webviewer code is bog standard

public class webservice_webview : Activity
{
    WebView web_view;

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);
        SetContentView(Resource.Layout.webview);
        string res = base.Intent.GetStringExtra("content");
        if (res.Length > 0)
        {
            web_view = FindViewById<WebView>(Resource.Id.webviewer);
            web_view.Settings.JavaScriptEnabled = true;
            web_view.LoadData(res, "text/html", null);
            web_view.SetWebViewClient(new websiteviewClient());
        }
        else
            return;
    }

    private class websiteviewClient : WebViewClient
    {
        public override bool ShouldOverrideUrlLoading(WebView view, string url)
        {
            view.LoadData(url, "text/html", null);
            return true;
        }
    }

    public override bool OnKeyDown(Android.Views.Keycode keyCode, Android.Views.KeyEvent e)
    {
        if (keyCode == Keycode.Back && web_view.CanGoBack())
        {
            web_view.GoBack();
            return true;
        }

        return base.OnKeyDown(keyCode, e);
    }
}
}

When the content is passed over and rendered, all that results is a dead webpage saying that the url data;text/html;null,[generated html] may have moved or has gone. How do I get the generated page to display?

Thanks

Paul

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1 Answer

  1. Editorial Team

    It might be worth check your assets are in the assets folder and are marked in the properties pane as being “AndroidAsset” – also please make sure capitalisation is correct.

    Assuming they are then you can just pass the assets direct to the webview using code like:

            var web = FindViewById<WebView>(Resource.Id.AboutWebView);
        web.LoadUrl("file:///android_asset/About/index.html");

    from https://github.com/slodge/mobile-samples/blob/master/MWC/MWC.Droid/Views/About/AboutXamarinView.cs

    If you do want to read in and manipulate the html text first, then try code like: Assets.Open("About/index.html") – i.e. without the file: scheme attached.

    In your second sample, the code for web_view.LoadData(res, "text/html", null); looks correct – but then I’m not sure what your logic inside ShouldOverrideUrlLoading does – that looks like it might just prevent things from loading?

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