How to avoid reverse engineering of an APK file?

Question

I am developing a payment processing app for Android, and I want to prevent a hacker from accessing any resources, assets or source code from the APK file.<

Answer 1

The other upvoted answers here are correct. I just want to provide another option.

For certain functionality that you deem important you can host the WebView control in your app. The functionality would then be implemented on your web server. It will look like it's running in your application.