Nexus 4 is my testing device for the most of my Android projects and since upgrading to Android 5.0 the device is not recognised from Android studio. The post will show how to enable the device in order to be available for app testing.
Follow these steps:
1. Enable Developer options in your device. To enable the developer mode, setting->About phone, tap Build number option 8 times continuously
2. Go to Settings-> Developer options
3. Turn on USB debugging
**If the above steps didn’t work try this step, Go to Settings->Security and turn on AllowUnknown Resources