Because Java permits only single inheritance, this restriction on abstract classes severely constrains their use as type definitions.Any class that defines all the required methods and obeys the ...

What is an Abstract Class? An abstract class is a class that is declared abstract —it may or may not include abstract methods. Abstract classes cannot be instantiated, but they can be subclassed. An ...

The Java Tutorial goes on to list bullets for when an abstract class should be considered and for when an interface should be considered. Unsurprisingly, these are derived from the previously ...