via http://www.aep-emu.de/

John GBC Lite is a Game Boy / Game Boy Color emulator for Android.
John GBC Lite is free to play but contains ads.
John GBC is the corresponding commercial and ad-free version.

Quote:
v2.20

  • improved graphics performance
  • fixed minor bugs
  • added "Manage game saves"
    You can change game saves folder. (Countermeasure for microSD problem on android 4.4)