The Department of Computer Science & Engineering
STUART C. SHAPIRO: CSE 115 C
A class extends its superclass.
Inheritance: a (child) subclass inherits attributes and behaviors
from its (parent) superclass, its superclass, etc., and it specializes
The superclass generalizes its subclasses.
A class may extend only one superclass. (No multiple inheritance.)
is-a: A dog is-a mammal, a mammal is-a vertebrate.
A superclass is abstract if it has at least one abstract
An abstract method has no body (not even an empty body).
abstract public void move();
This requires every subclass to have this method.
A class with no abstract methods is concrete.
Only concrete classes may have instances.
super(args);: Call to the parent class's
Must be the first statement of the child's constructor.
If missing, Java compiler will insert
May have multiple methods (esp. constructors) with same name, but different signatures. Compiler will arrange for a call to the matching one.
this: The current instance.
Additional access modifier:
private: accessible only to class within which it's declared.
protected: accessible to class within which it's declared, and all subclasses (and every class in package).
public: accessible to every class.
See Inheritance demonstration and its documentation.