I\'m running on Windows 7, and I\'ve updated all the drivers as it says on the Android developer website regarding using hardware devices. However, Eclipse is still not reco
To enable USB debugging, go to settings, about phone and then at the bottom tap build number seven times. This will enable the developer settings where you can enable USB debugging.
I had to resort to a clean install of Windows 7 x64 to fix this issue.
I tried all steps/variants in the other answers. No luck. Device Manager would show my 'Android Device / Android Composite ADB Interface' working properly with the 7.0.0.1 driver from Google, but nothing could get 'adb devices' to show my Nexus 4.
I used USBDeview to uninstall every USB device that had connected to my computer except my keyboard and mouse. No luck.
I enabled 'Show hidden devices' in Device Manager and uninstalled anything related to USB. No luck.
I added Google's vendor ID to adb_usb.ini. No luck. I deleted adb_usb.ini and ran 'android update adb'. No luck.
I brought my Nexus 4 to my brother's apartment to confirm it wasn't faulty. Worked on his machine without a hiccup.
I'm glad the clean install worked, because further troubleshooting was going to require swapping motherboards or buying a MacBook.
Boy, that escalated quickly.
I had the same problem and none of the above worked, but the following solution worked for me:
On my Nexus 4:
Go to Settings
Choose Developer options (from the end of the list after pressing seven times on "About phone")
Check the "USB debugging" and press OK.
How to do it on Windows 8 (I think, it will work for Windows 7 too)
Do not forget, that Android 4.2 now want you to submit RSA key from your computer, look at your device screen.
To enable developers options on Android 4.2: Open Settings -> About phone -> Tap on Build Number 7 times.
You need to install USB drivers only if you use Windows (If you're using MAC/Linux, most likely it will work fine without any driver installations)
in the following link they describe how to do it:
http://developer.android.com/tools/extras/oem-usb.html
In short:
For me, it was Nexus 4 and Windows 7. I reinstalled the drivers, changed to PTP - basically went through everything.
Clicking the tab that said MainActivity.java rather than activity_main.xml in Eclipse fixed it for me.