The University of Akron
Summit College
2440: 160
Java Programming
Introduction to Computers & Java
Professor: Enoch E. Damson
Parts of an Information System
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Hardware
Software
Procedures
Data
People
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Hardware
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Physical components of a computer
Consists of:
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Input devices
Processor or Central Processing Unit (CPU)
Main memory
Secondary storage devices
Output devices
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Input Devices
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Collects data for the computer
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Common devices include:
Keyboard
 Mouse
 Scanner
 Digital camera
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Central Processing Unit (CPU)
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Fetches instructions, follow the instructions, and
produce some resulting data
Measured in terms of its speed in hertz (MHz,
GHz)
Consists of two parts:
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Control Unit – coordinates all of the computer’s
operations
Arithmetic & Logic Unit (ALU) – performs
mathematical operations
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Main Memory
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Commonly known as the random-access memory
(RAM)
Measured in terms of its size in bytes (KB, MB, GB)
RAM is usually a volatile type of memory for temporary
storage
Divided into sections (bytes) that hold equal amount of
data
Each byte is made up of 8 binary digits (bits) that use
0 and 1 to represents on and off “switches”
Each byte is a assigned a unique number known as an
address, which are ordered from lowest to highest
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Secondary Storage Devices
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Type of memory that hold data for long periods
of time
Measured in terms of their size in bytes (KB,
MB, GB)
Common types of secondary storage devices
include:
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Hard disks
Jump drives
Zip disks
Floppy disks
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Output Devices
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Formats and presents processed data
(information) to the outside world
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Common devices include:
Monitors
 Printers
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Software
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Programs that run on a computer
Has two general categories:
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System software – enables application software to
interact with the computer hardware
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E.g. operating systems, utilities, device drivers, and
programming languages
Application software – programs that solve specific
problems or perform general operations useful to the
user
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E.g. word processors, spreadsheets, etc
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Procedures
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Rules or guidelines for people to follow
when using software, hardware, and data
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Guidelines are documented in manuals
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Data
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Raw facts entered into the computer
system for processing
Processed to produce information
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People
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Making people more productive is what
computers are all about
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Users include:
Analysts
 Designers
 Developers
 End-users
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Computer Program
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Set of instructions that enables the computer to
solve a problem or perform a task
The instructions are called algorithms
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A computer’s CPU can only process algorithms written
in machine language – consisting of binary
numbers (0s and 1s)
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E.g. 1011010000000101
Each different type of CPU has its own machine
language
Algorithms written with programming languages
are much easier to understand
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Computer Programming
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An art and a science of creating
instructions to solve problems and perform
tasks
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An art because every aspect of the program
should be carefully designed
A science because of the need to indulge in
the tasks of analyzing, experimenting,
correcting, and redesigning
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Program Development
(Programming) Cycle
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The process of writing instructions (programs)
for a computer to solve a problem
Programming steps include:
1.
2.
3.
4.
5.
Creating program specifications
Designing the application
Writing source code
Compiling/Interpreting programs
Executing (running) program
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Program Development
(Programming) Cycle…

Creating program specifications –
the requirements the application must
meet
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Program Development
(Programming) Cycle…
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Designing the application – create file
formats, screen layouts, and algorithms
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Algorithm – a sequence of procedures,
programming code, or commands that are used as
part of a program or result in a program
Tools used in designing the sequential and logical
structure of a program include:
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Flowchart – uses symbols for program design
Pseudocode – uses natural English for program design
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Program Development
(Programming) Cycle…
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Writing source code – the code must be
written, tested and debugged
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Source code (file) – the file with the actual code
which is written with a programming language of
choice in a text editor
Debugging – the process of going through program
code to locate and fix errors such as:
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Syntax errors – grammatical mistakes in program language
use
Logical errors – logical mistakes in a program
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Program Development
(Programming) Cycle…

Compiling/Interpreting programs – the
source code is translated in its entirety at one
time (compiled) or a single line at a time
(interpreted) from high-level program
instructions into machine language, and
executed if no errors are found (run)
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Program Development
(Programming) Cycle…
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Compiling/Interpreting programs
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Compiler – a system software program that translates an entire
high-level program (source code) at one time into machine
language (object code grouped together in files called library
files) that the computer can interpret and execute
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It gives no feedback until the entire program has been compiled
Interpreter – a system software program that translates a
single line at a time in a program
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An immediate feedback is given if the code contains an error
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Program Development
(Programming) Cycle…
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Executing (running) program – the compiled
or interpreted code is executed if no errors are
found
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Executable code – a linker or link editor resolves
object code references to other programs by creating
an executable code.
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Programming Languages
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Invented to ease the task of programming with the use
of words instead of binary numbers
Programming languages have evolved in generations
and are improved over the years
The generations of programming languages include:
 Low-level languages
 High-level languages
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Programming Languages…
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Low-level languages – include:
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Machine language (1st Generation) – instructions are
coded as a series of 0s and 1s and are unique to a particular
computer
Assembler language (2nd Generation) – instructions are
coded using some recognized symbols called mnemonics
(memory aids) and are also unique to a particular computer

Example: MUL is used to represent a multiply instruction. An
assembler translates the mnemonics into 0s and 1s
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Programming Languages…
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High-level languages – programs instructions are
often written in English-like expressions in languages
such as:
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3rd Generation languages – instructions are coded at the
programmer’s convenience but cannot be executed in their original
form (source code)
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A compiler or interpreter is needed to translate the language syntax into lowlevel machine language to be executed.
Examples include: FORTRAN (FORmula TRANslator)-1955, Pascal1968, C-1972, C++-1980s, Java-1990
4th Generation languages – Has a graphical user interface (GUI)
that combines a code editor, compiler, debugger, linker, and
executor into a single Inter-Development Environment (IDE).
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Examples include: Visual Basic, Delphi, PowerBuilder, Visual.NET, etc
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Programming Language Elements
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Every programming language uses the following
general program elements:
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Syntax – rules of a programming language
Comments – non executing programming language statements
Constant data – raw data used in programming such as
numbers, strings, etc
Data output – displaying data on a screen or sending data to a
file
Data input – receiving data from the keyboard or file
Variables – named memory locations for data storage
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Programming Language Elements…
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Other programming language elements include:
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Data types – specifies the types of data native to the
programming language
Keywords – words with a special meaning in the programming
language
Operators – symbols or words that perform operations on
operands
Selections (Condition testing)
Repetitions (Looping structures)
Arrays
Files/Databases
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Methods of Programming
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Two primary methods of programming are:
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Procedural – creates programs made up of variables
and procedures
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Variable – named storage location in a computer’s memory
Procedure – set of programming language statements that
perform a specific task
Object-oriented – creates programs made up of
objects (instances of a class)
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Object – a software entity with attributes (fields) and
procedures (methods)
Class – specifies the attributes and methods of objects
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Principles of Object-Oriented
Programming (OOP)
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Encapsulation – grouping data (fields, methods, etc)
into a single object
Information Hiding (Abstraction) – hiding an
object’s data from other objects
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The object’s methods are used directly access its data
Typically, the object’s data is hidden but allows its methods to
be accessed
Inheritance – deriving classes (subclasses) based on
other existing classes (superclasses)
Polymorphism - using the same procedure name or
operator with different types of arguments
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There are 2 types of polymorphism: overloading and
overriding
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History of Java
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In 1991 the Green Team was formed at Sun
Microsystems to develop a hand-held device (named
*7) to control home entertainment devices
James Gosling (the project leader) created the Oak
language for the project
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The Oak language translated programs into byte code for
different processors
Oak (renamed Java) was later used to develop a Web browser
named HotJava – which was able to download and run small
Java programs known as applets
HotJava was demonstrated in 1995 which made Java popular
Netscape later incorporated Java into its Navigator browser
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Types of Java Programs
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Two types of Java programs are:
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Application – stand-alone programs that run
on a computer
Applets – programs that are transmitted over
the Internet from a Web server and executed
on a Web browser
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Properties of Java
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Object-Oriented – uses objects to perform specific tasks
Portable – enables programs to behave identical on different
platforms like: Mac, Windows, Solaris (UNIX)
Compiles into byte code instead of machine language – the
byte code is read by the Java Virtual Machine (JVM) – which
interprets the code for different processors
“Architecture-neutral” – the byte code that comes out of the
compiler will run on any processor and operating system
Can be embedded on Web pages – applets are downloaded and
ran from Web pages
Secured – Web browsers run applets in a secure environment
within a computer’s memory
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The Java Compiler & Java Virtual
Machine (JVM)
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Text editors are used to write Java programming
statements (source code) and saved in a source file
(.java extension) and translated (compiled) by a
compiler
Compiler – program that translates source code into an
executable form
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Java compilers translate source code into a file (.class
extension) containing byte code
The byte code instructions (not machine language) are executed
by the Java Virtual Machine (JVM)
The JVM simulates a computer whose machine language is the
Java byte code
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Java Program Development Process
1.
The programmer uses a text edit to
create a Java source code file (.java
extension)
Text
Editor
Source
File
2.
The programmer runs the compiler to
translate the source code file into a byte
code file (.class extension)
Java
Compiler
Byte Code
File
3.
The Java Virtual Machine (JVM) reads
and executes each byte code instruction
Java Virtual
Machine
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Java Editions
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The software used to create Java programs is
known as the Java Development Kit (JDK) or
the Software Development Kit (SDK)
Some Java editions include:
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Java Standard Edition (Java SE) – used for
writing Java applications and applets
Java Enterprise Edition (Java EE) – used to
create business client/server and Web server-based
applications
Java Micro Edition (Java ME) – runtimeenvironment for consumer products like cell phones,
pagers, etc
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Java Integrated Development
Environments (IDE)
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Consists of text editor, compiler, debugger, and
other utilities integrated into a package
Current popular Java IDEs include:
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Eclipse (http://www.eclipse.org)
NetBeans (http://www.netbeans.org)
IntelliJ IDEA (http://www.jetbrains.com/idea)
jGRASP (http://www.jgrasp.org)
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Compiling & Running Java
Programs
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javac is used to compile Java programs
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A .class file is created if no are found
java is used to run Java programs
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E.g. javac Hello.java
E.g. java Hello
Two types of errors (bugs) are:
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Syntax errors – mistakes that violate the rules of
the programming language
Logical errors – mistakes that cause programs to
produce erroneous results
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