Software - 1960s to 1970s
 Computer software is customdeveloped
 Most computer systems are
large and have unique
configurations
 Languages are procedural
(FORTRAN, COBOL, BASIC, C)
 A computer system costs
$100K and up
 Source code is usually
delivered
Software - 1980s
 Development of
DOS/Wintel platform
 PCs become ubiquitous
and standardized
 Software becomes an
off-the-shelf product
 Source code is not
delivered
Software - 1990s to 2000s
 "Free software" movement /
opensource
 Rise of object-oriented
programming (e.g. C++, Java)
 Rise of distributed computing:
client-server technology and
web servers/Java
Software - 2010s +
 Cloud/web applications
 Mobile / responsive design
 Niche/business market products
 Mass consumer free.
Software Development
1950-1960's:
 Emphasis on efficiency
 fast algorithms
 small program size
 limited memory use
Now:
 Emphasis on
 programmer’s productivity
 team development
 reusability of code
 easier maintenance
 Often cryptic code
 Not user-friendly
 Upgradability
 Better documented
 User-friendly
Programming Languages
Assembly
languages
1940
1950
C
C#
LISP
Scheme
Logo
1960
1970
Fortran
Machine
code
C++
1980
Pascal
Java
1990
2000
Python
Basic
Smalltalk Smalltalk-80
Top Computer Languages 2014
Source Code, Binary Code, and Compilers
 Source Code
 Written in “Higher Level Computer Language“
 Trained programmer can read, understand, critique, edit and Improve
 Computer CANNOT use in this form
 Designed to show logic and structure
 Compiler Software
 Converts source to machine-readable form
 Strips out human-readable comments and logic
 Results in Binary Code - “1’s and 0’s”
 Machine Code
 Executable by computers
 Used in binary or “object” form
 Conventional form of distributed proprietary software
Programs written in some languages need not be compiled to be read
by a computer (e.g., BASIC, PHP, HTML,JAVASCRIPT)
Java’s Compiler + Interpreter
Editor
Compiler
:
:
7
K


Hello.java
Hello.class
Interpreter
Interpreter
:

Hello,
World!

Why Bytecodes?
 Platform-independent
 Load from the Internet faster than source code
 Interpreter is faster and smaller than it would be for Java
source
 Source code is not revealed to end users
 Interpreter performs additional security checks, screens
out malicious code
Types of Programs
 Console applications
 Applets
 GUI applications
 Web Services
Console Applications
 Simple text dialog:
prompt  input, prompt  input ...  result
C:\javamethods\Ch02> path=%PATH%;C:\Program Files\Java\jdk
1.5.0_07\bin
C:\javamethods\Ch02> javac Greetings2.java
C:\javamethods\Ch02> java Greetings2
Enter your first name: Josephine
Enter your last name: Jaworski
Hello, Josephine Jaworski
Press any key to continue...
GUI Applications
Menus
Clickable
panel
Buttons
Slider
OOP —
Object-Oriented Programming
 An OOP program models a world of active objects.
 An object may have its own “memory,” which may
contain other objects.
 An object has a set of methods that can process
messages of certain types.
OOP (cont’d)
 A method can change the object’s state, send
messages to other objects, and create new objects.
 An object belongs to a particular class, and the
functionality of each object is determined by its class.
 A programmer creates an OOP application by defining
classes.
Inheritance
 A programmer can define hierarchies of classes
 More general classes are closer to the top
Person
Child
Baby
Toddler
Adult
Teen
OOP Benefits
 Facilitates team development
 Easier to reuse software components and write reusable
software
 Easier GUI (Graphical User Interface) and multimedia
programming
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