android studio can't connect to debug devices

in android studio: tools->android->enable adb integration(this should be checked) uncheck this, then check again. this solved me this problem. (it restarts the adb integration)

This is how I solved same issue:

1) I don't think that it is important but I: updated all pending for update ADT stuff. And restarted OS. But I still was unable to debug

2) Next: I launched AS. Opened terminal and ran this:

./adb get-state

• daemon not running. starting it now on port 5037 *
• daemon started successfully *

As you can see daemon started automatically after I asked for its state. So I did not do nothing more. Just tried to debug and this time debugging worked.

P.S. After I restarted AS debugging continued working. So there was no need in terminal manipulations anymore

Well, what it worked for me: I have change my /etc/hosts file and make sure that those 3 lines are on the bottom of the file:

127.0.0.1       localhost
255.255.255.255 broadcasthost
::1             localhost