Final answer:
If two compared objects in a compareTo method are not type compatible, a ClassCastException is thrown by the method.
Step-by-step explanation:
If two compared objects in a compareTo method are not type compatible, a ClassCastException is thrown by the method. This exception occurs when an attempt is made to cast an object to a type that it is not compatible with, resulting in a runtime error. For example, if you try to compare a String object with an Integer object using the compareTo method, a ClassCastException will be thrown.