Hot deploy compilation is done by the application itself, so please make sure your Tomcat use JDK, not JRE. In particular, check if you have JAVA_HOME or JRE_HOME environment variables pointing to a JRE - then it is used by Tomcat.
I am having this same error. I have CUBA pointing to JDK 1.8.0.131, however, I do not see the setting to adjust the Tomcat server. Where would that be?