Question

Monodroid does not yet natively support JavaScriptInterface with WebView.

I’m looking for an example .java file that can be used with this workaround.

IntPtr JavaScriptInterface_Class = JNIEnv.FindClass ("the/package/for/JavaScriptInterface");
IntPtr JavaScriptInterface_ctor = JNIEnv.GetMethodID (JavaScriptInterface_Class, "<init>", "()V");
IntPtr instance = JNIEnv.NewObject (JavaScriptInterface_Class, JavaScriptInterface_ctor);

appView.AddJavascriptInterface (new Java.Lang.Object (instance), "Android");

Answer 1

You could use a custom .java such as:

// TODO: use an actually valid package name. :-)
package the.package.for;

public class JavaScriptInterface {
    // The JNI in the original question uses a default constructor.
    // Either provide one explicitly or use the implicit one...
    public JavaScriptInterface ()
    {
    }

    // TODO: add any methods you want invokable from JavaScript here.
}

Don’t forget to set the Build action for your .java file to to AndroidJavaSource.