Summary
Section 9.1 Introduction
Software reuse reduces program-development time.
The direct superclass of a subclass (specified by the keyword extends in the first line of a class declaration) is the superclass from which the subclass inherits. An indirect superclass of a subclass is two or more levels up the class hierarchy from that subclass.
In single inheritance, a class is derived from one direct superclass. In multiple inheritance, a class is derived from more than one direct superclass. Java does not support multiple inheritance.
A subclass is more specific than its superclass and represents a smaller group of objects.
Every object of a subclass is also an object of that class’s superclass. However, a superclass object is not an object ...
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