d2j-dex2jar.sh someApk.apk
Follow this guide: https://code.google.com/p/dex2jar/wiki/UserGuide
--Update 10/11/2016--
Found this ClassyShark from Google's github pretty easy to view code from APK.
https://github.com/google/android-classyshark
// make sure that you downloaded release https://github.com/pxb1988/dex2jar/releases (for the ppl who coldnt find this link in /dex2jar/downloads/list