2: Chapter Objects and Primitive Data
Presentation slides for
Java Software Solutions
Foundations of Program Design
Third Edition by John Lewis and William Loftus
Java Software Solutions is published by Addison-Wesley
Presentation slides are copyright 2002 by John Lewis and William Loftus. All rights reserved. Instructors using the textbook may use and modify these slides for pedagogical purposes.
Objects and Primitive Data
Now we can explore some more fundamental
programming concepts
Chapter 2 focuses on:
predefined objects primitive data the declaration and use of variables expressions and operator precedence creating and using objects class libraries Java applets drawing shapes
2
I ntroduction to Objects
An object represents something with which we can
interact in a program
An object provides a collection of services that we
can tell it to perform for us
The services are defined by methods in a class that
defines the object
A class represents a concept, and an object
represents the embodiment of a class
A class can be used to create multiple objects
3
Objects and Classes
A class (the concept) An object (the realization)
John's Bank Account Balance: $5,257 Bill's Bank Account Balance: $1,245,069 Mary's Bank Account Balance: $16,833
Bank Account
Multiple objects from the same class
4
I nheritance
One class can be used to derive another via
inheritance
Classes can be organized into inheritance
hierarchies
Account
Charge Account
Bank Account
Savings Account
Checking Account
5
Using Objects
The System.out object represents a destination to
which we can send output
In the Lincoln program, we invoked the println
method of the System.out object:
System.out.println ("Whatever you are, be a good one.");
object
meth...
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