L'héritage

A la distinction déjà vue entre héritage simple et héritage multiple, on ajoute également celle-ci :

Définition 4.1   Héritage d'implémentation : une sous-classe hérite de comportement de sa super-classe, où d'une partie de ses attributs.

Définition 4.2   Héritage d'interface : une sous-classe n'hérite d'aucun comportement de sa super-classe, et d'aucun de ses attributs.

En Java, il existe une héritage simple d'implémentation et un héritage multiple d'interface. Ainsi le conflit d'opérations sur un objet n'existe pas.

class SC{}
Interface I1{}
Interface I2{}
Interface I3{}
class C extends SC implements I1, I2, I3{}

Attention à l'héritage des constructeurs, notamment avec les constructeurs sans arguments et l'utilisation de super().

En Java, les classes abstraites sont possibles, les classes Object, Class et ClassLoader modifient la hiérarchie des classes. Ce qui suit est extrait de la documentation.

java.lang 
Class Object

java.lang.Object

public class Object

Class Object is the root of the class hierarchy. Every class has Object as a superclass. All objects, including arrays, implement
the methods of this class.

java.lang 
Class Class

java.lang.Object
  |
  +--java.lang.Class

public final class Class
extends Object
implements Serializable

Instances of the class Class represent classes and interfaces in a running Java application. Every array also belongs to a class
that is reflected as a Class object that is shared by all arrays with the same element type and number of dimensions. The
primitive Java types (boolean, byte, char, short, int, long, float, and double), and the keyword void are also represented as
Class objects. 

Class has no public constructor. Instead Class objects are constructed automatically by the Java Virtual Machine as classes are
loaded and by calls to the defineClass method in the class loader.

java.lang 
Class ClassLoader

java.lang.Object
  |
  +--java.lang.ClassLoader

Direct Known Subclasses: 
      SecureClassLoader 

public abstract class ClassLoader
extends Object

The class ClassLoader is an abstract class. A class loader is an object that is responsible for loading classes. Given the name of
a class, it should attempt to locate or generate data that constitutes a definition for the class. A typical strategy is to transform the
name into a file name and then read a "class file" of that name from a file system. 

Every Class object contains a reference to the ClassLoader that defined it.