If you’re doing Android development and use a device running Android 4.2.2, your adb might have stopped working, saying your device was “offline”. To fix this, update your Android SDK and SDK Tools including adb. Android 4.2.2 has introduced an ADB USB debugging whitelist amongst other security improvements, and older versions of the Platform Tools do not support this handshake.
Run adb version to find out which version of ADB you are running. If it is less than 1.0.31, you should upgrade.
You can update your tools from the SDK Manager or by downloading the newest ADT bundle or SDK tools.
Happy hacking!