I\'m trying to install a platform but when I open Android Manager then I click Available Software then select the https://dl-ssl.google.com/android/repository/repository.xml
After 7 long hours of searching I finally found the way!! None of the above solutions worked, only one of them pointed towards the issue!
If you are on Win7, then your Firewall blocks the SDK Manager from retrieving the addon list. You will have to add "android.bat" and "java.exe" to the trusted files and bingo! everything will start working!!