title: Injecting code into APK
body: <p>I know you can decompile code using apktool and recompile it again, but my question is how would you be able to inject large amounts of code into an apk and execute it.</p>
  
  <p>I see that amazon's appstore drm is doing this Im assuming, since they say they are wrapping the apk with their own code, and once you decompile that apk you see that they have added there own class com.amazon etc.</p>
  
  <p>How are they acheving this? </p>