i have tried it many times but its giving me same error.how to set the proxy so that this error is solved
In my case issue occurred after following:
I selected proxy settings from Android Studio settings when I was working in a network behind a proxy. When I disconnected from that network and connected to home network which doesn't have a proxy, I removed the proxy settings from Android Studio, but gradle seemed to take the old proxy settings.
The problem was that gradle had also saved the proxy settings in following file when I set proxy settings in Android Studio, but it hasn't got removed when I removed proxy settings from Android Studio.
%HOME%\.gradle\gradle.properties
When I removed the proxy settings from this file, gradle sync worked again.