title: Modify classes.dex and repack .apk file
body: <p>I want to modify classes.dex file in .apk file of my Android application and make a new .apk file. I already know how to decompile .apk file using tools such as apktool and then recompile it. My issue is to modify classes.dex file exactly, not a .smali code.</p>
  
  <p>I tried to make a .zip archive with modified classes.dex file and to change it's extension to .apk, but I failed to install this .apk on my Android gadget.</p>