1. CIS 234: Object-Oriented Programming with Java
Dr. Ralph D. Westfall
March, 2010

2. Overview what is programming? object-oriented programming
introduction to Java
objects
integrated development environment
advantages and disadvantages

3. What is Programming? program = list of steps for a computer
like a recipe
steps can be in different "languages"
Java, Visual Basic, C++, Assembler, etc.
how many languages? (one answer)
each language has own syntax (rules)
like grammars in human languages
175 as of 9/26/6

4. Why Is Programming Hard?
a computer is very "stupid"
it doesn't understand anything: you have to tell it exactly what to do
have to follow all the rules (syntax) of the language as you are telling it what to do
it takes a lot of practice to be able to tell the computer exactly what to do, in perfect syntax ["Simon says:"]

5. Computer Language Types
low level vs. high level
general purpose vs. special purpose
procedural vs. object-oriented

6. Language Levels low level: machine language high level
language that a computer understands
binary numbers e.g
high level
languages that people can understand
words like "if," "else," "for," "true"

7. Translation
convert high level languages into a computer's machine language
compiled
all source code in a file converted into an object code file, then executed all at once
interpreted
source code converted into machine language and executed, one line at a time

8. Translation - 2 some languages are both compiled and interpreted
1st compiled into "intermediate language" (like a machine language)
Java is first compiled into "bytecode" by Java Virtual Machine (JVM; see diagram)
Visual Basic.NET works like this also
intermediate language is then interpreted/runs one line at a time

9. Special Purpose Languages
don't do everything
do a few things very well
example: markup languages
HTML, XML
display text, images, etc.
not good for calculations

10. Procedural Languages one step after another
data and actions (procedures) are separated
example: plans for a large wedding
data = list of all food & supplies
procedures = all instructions for every part of the wedding

11. Object-Oriented Languages
newer approach to programming
data and procedures that use it are together in the same place (object)
objects can operate independently
event-driven programs
instead of 1 step after another

12. Object-Oriented Languages - 2
encapsulation or "data hiding"
can only access data through object's private procedures (send message to object)
inheritance
new objects extend capabilities of parents
HourlyEmployee inherits all properties and methods of Employee object

13. Object-Oriented Advantages
real world (supposedly) is somewhat like objects
employee, car, dog
different objects can hook together
like Lego blocks
objects can be reused
instead of "reinventing the wheel"

14. Java developed by Sun Microsystems an object-oriented language
"chopped down" from C/C++
similar syntax
omits C features that cause crashes
has added features not in C/C++
built-in networking capabilities make it work well with Internet

15. More About Java "cross-platform transparency"
not designed to only run well on certain computers/operating systems
runs on any computer that has Java Virtual Machine (JVM) software
one standardized version, not multiple versions of Java
unlike multiple C & UNIX versions
J# is similar, but it is NOT Java

16. Review Questions Computer programs are like ________?
A programming language syntax is like _______________?
Why is computer programming hard?
How are low level and high level computer languages different?
How are compiled and interpreted computer languages different?

17. Review Questions - 2
How are general purpose languages different from special purpose ones?
give examples of each
How are procedural languages different from object oriented ones?
What is inheritance?
What is data hiding?

18. Review Questions - 3
Name some advantages of object oriented programming
What company created Java?
What is the Java Virtual Machine (JVM)?
What is cross-platform transparency?
How many different versions of Java are there?