Cannot launch AVD in emulator:QT library not found
This seems to be an issue relating to the recent update. A temporary solution is to launch emulator from within the /path/to/android-sdk/tools directory in the commandline.
See https://code.google.com/p/android/issues/detail?id=235461 to follow the issue.
All other answers did not work for me as "Android Emulator" was not installed with a standard installation of Android Studio. Make sure you have installed it and then try other answers if required.