Now, we turn our focus to the mothership of the Java class inheritance hierarchy, java.lang.Object. What you’ll learn in this Java tutorial ...

A method might accept a specific type and its subclasses, but you want to restrict usage to a select few implementations of your own design. Java's open inheritance model can feel like an open ...

This looks like the Liskov substitution principle that Uncle Bob Martin described: Substitute a derived class (Square) for a base class (Rectangle). From the standpoint of the compiler, the above code ...