"Type R cannot be resolved to a variable" after Android SDK updated

If you get the error of "Type R cannot be resolved to a variable" after Android SDK and ADT updated. Try to find and install any available update in Android SDK.

In my case, after update Android SDK Tools rev 22, and also ADT. I get error of "Type R cannot be resolved to a variable" in my projects, and any new project!

- Start Android SDK Manager again. Two more update available, Android SDK Platform-tools and Android SDK Build-tools. It was not available in the previous update.

- Install the update packages.

- Close and restart Eclipse.

- Problem solved.