It seems the JDK installer on Windows 7 does not install a path variable to find javac. I can set it manually. But I do not like to change it with any new update of JDK. Does it use any other environment variable? Or is it really that weird?
I don't know of a JDK installer which sets the PATH on any system.
You can install several version of the JDK and if you use an IDE, you don't need to set the path. If you want to use javac manually (don't ask me why you would) you need to set the PATH to specific which version to use.