WebView hides soft keyboard during loadUrl(), which means a keyboard cannot stay open while calling javascript

Question

Since the way you call javascript on a WebView is through loadUrl(\"javascript: ... \"); The keyboard cannot stay open.

The loadUrl() method calls loadUrlImpl() , wh

Answer 1

I could implement cottonBallPaws's idea to use the internals of WebView with reflection, and got it to work for my 4.2 device. There are gracious fallbacks for Android versions older than KitKat.

The code is written in Xamarin, but it should be easily adaptable to native Java code.

/// 

/// Executes a JavaScript on an Android WebView. This method offers fallbacks for older
/// Android versions, to avoid closing of the soft keyboard when executing JavaScript.
/// 
/// The WebView to run the JavaScript.
/// The JavaScript code.
private static void ExecuteJavaScript(Android.Webkit.WebView webView, string script)
{
    if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.Kitkat)
    {
        // Best way for Android level 19 and above
        webView.EvaluateJavascript(script, null);
    }
    else
    {
        try
        {
            // Try to do with reflection
            CompatExecuteJavaScript(webView, script);
        }
        catch (Exception)
        {
            // Fallback to old way, which closes any open soft keyboard
            webView.LoadUrl("javascript:" + script);
        }
    }
}

private static void CompatExecuteJavaScript(Android.Webkit.WebView androidWebView, string script)
{
    Java.Lang.Class webViewClass = Java.Lang.Class.FromType(typeof(Android.Webkit.WebView));
    Java.Lang.Reflect.Field providerField = webViewClass.GetDeclaredField("mProvider");
    providerField.Accessible = true;
    Java.Lang.Object webViewProvider = providerField.Get(androidWebView);

    Java.Lang.Reflect.Field webViewCoreField = webViewProvider.Class.GetDeclaredField("mWebViewCore");
    webViewCoreField.Accessible = true;
    Java.Lang.Object mWebViewCore = webViewCoreField.Get(webViewProvider);

    Java.Lang.Reflect.Method sendMessageMethod = mWebViewCore.Class.GetDeclaredMethod(
        "sendMessage", Java.Lang.Class.FromType(typeof(Message)));
    sendMessageMethod.Accessible = true;

    Java.Lang.String javaScript = new Java.Lang.String(script);
    Message javaScriptCodeMsg = Message.Obtain(null, 194, javaScript);
    sendMessageMethod.Invoke(mWebViewCore, javaScriptCodeMsg);
}