Myself trying to update an existing apk installed in my tablet through my own web server.Almost i have done with the help of google and stackoverflow.The thing i have struggeled is, i need to update an apk with alert dialog with single positive button like update.
I have used this peice of code from the link self upgrading own apk via net programmatically on android which gives me an alert with both positive and neutral button like this picture 
My spec is that, i need to install an apk forcely with update button alone after downloading it from sever