Multiple Inheritance?
Multiple inheritance is where one class has more than one super-class and inherits features from all parent classes.
Some programming languages, like C++ and Ruby, support Multiple Inheritance. Java, however, does not support multiple inheritance. Java does not permit you to extend more than one class. Although, a super-class itself may be a sub-class (of another class higher up in the hierarchy), allowing multi-level inheritance.
The reasons for not permitting multiple inheritance are primarily technical (compiler design) and, at this point, historical artifacts. You can refer to Oracle's Java Tutorial: Inheritance for their explanation of why Multiple Inheritance is not permitted.
Note that it is perfectly okay for a class to have multiple sub-classes.
Resources
- TutorialsPoint has a well-written entry on inheritance, with a nice diagram for types of it, here.