Chapter 2 Java

Summary Chapter 2 about Programming Of java and UML

1.   Object Orientation Is a significantly different way of thingking about solving problems and developing software solutions
2. An object-Oriented system is one that has been designed using abstraction with objects, encapsulated classes, communication via messages, object lifctimc, class hicrarchics, and polymorphism.
3. An object represents an instance of a real or abstract thing.
4.  A class is the definition of the attributes and methods needed to model a related group of objects
5.  Classes can be organized into hierarchies. Association is a relationship between classes. Aggregation and composition represent whole/part relationships. Inheritance represents generalization/specialization
6.  An understanding of how objects are created and implemented can make it easier to write good OO programs

 

Note that the UML uses an open arrowhead pointing to the more general class to show inheritance. The animal hierarchy, a mammal inherits from Animal, and so on