The University of Akron Summit College

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The University of AkronSummit College

• 2440 160Java Programming
• Introduction to Computers Java
• Professor Enoch E. Damson

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Parts of an Information System

• Hardware
• Software
• Procedures
• Data
• People

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Hardware

• Physical components of a computer
• Consists of
• Input devices
• Processor or Central Processing Unit (CPU)
• Main memory
• Secondary storage devices
• Output devices

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Input Devices

• Collects data for the computer
• Common devices include
• Keyboard
• Mouse
• Scanner
• Digital camera

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Central Processing Unit (CPU)

• Fetches instructions, follow the instructions,
  and produce some resulting data
• Measured in terms of its speed in hertz (MHz,
  GHz)
• Consists of two parts
• Control Unit coordinates all of the computers
  operations
• Arithmetic Logic Unit (ALU) performs
  mathematical operations

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Main Memory

• 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

• 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
• Hard disks
• Jump drives
• Zip disks
• Floppy disks

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Output Devices

• Formats and presents processed data (information)
  to the outside world
• Common devices include
• Monitors
• Printers

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Software

• Programs that run on a computer
• Has two general categories
• System software enables application software to
  interact with the computer hardware
• 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
• E.g. word processors, spreadsheets, etc

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Procedures

• Rules or guidelines for people to follow when
  using software, hardware, and data
• Guidelines are documented in manuals

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Data

• Raw facts entered into the computer system for
  processing
• Processed to produce information

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People

• Making people more productive is what computers
  are all about
• Users include
• Analysts
• Designers
• Developers
• End-users

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Computer Program

• Set of instructions that enables the computer to
  solve a problem or perform a task
• The instructions are called algorithms
• A computers CPU can only process algorithms
  written in machine language consisting of
  binary numbers (0s and 1s)
• 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

• An art and a science of creating instructions to
  solve problems and perform tasks
• 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

• The process of writing instructions (programs)
  for a computer to solve a problem
• Programming steps include
• 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

• Designing the application create file formats,
  screen layouts, and algorithms
• 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
• Flowchart uses symbols for program design
• Pseudocode uses natural English for program
  design

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Program Development (Programming) Cycle

• Writing source code the code must be written,
  tested and debugged
• 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
• 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

• Compiling/Interpreting programs
• 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
• 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
• An immediate feedback is given if the code
  contains an error

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Program Development (Programming) Cycle

• Executing (running) program the compiled or
  interpreted code is executed if no errors are
  found
• 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

• 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

• Low-level languages include
• 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

• High-level languages programs instructions are
  often written in English-like expressions in
  languages such as
• 3rd Generation languages instructions are coded
  at the programmers convenience but cannot be
  executed in their original form (source code)
• A compiler or interpreter is needed to translate
  the language syntax into low-level machine
  language to be executed.
• Examples include FORTRAN (FORmula
  TRANslator)-1955, Pascal-1968, 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).
• Examples include Visual Basic, Delphi,
  PowerBuilder, Visual.NET, etc

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Programming Language Elements

• Every programming language uses the following
  general program elements
• 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

• Other programming language elements include
• 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

• Two primary methods of programming are
• Procedural creates programs made up of
  variables and procedures
• Variable named storage location in a computers
  memory
• Procedure set of programming language
  statements that perform a specific task
• Object-oriented creates programs made up of
  objects (instances of a class)
• 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)

• Encapsulation grouping data (fields, methods,
  etc) into a single object
• Information Hiding (Abstraction) hiding an
  objects data from other objects
• The objects methods are used directly access its
  data
• Typically, the objects 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
• There are 2 types of polymorphism overloading
  and overriding

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History of Java

• 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
• 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

• Two types of Java programs are
• 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

• 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 computers memory

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The Java Compiler Java Virtual Machine (JVM)

• 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
• 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

• The programmer uses a text edit to create a Java
  source code file (.java extension)
• The programmer runs the compiler to translate the
  source code file into a byte code file (.class
  extension)
• The Java Virtual Machine (JVM) reads and executes
  each byte code instruction

Text Editor
Source File
Java Compiler
Byte Code File
Java Virtual Machine
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Java Editions

• 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
• 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) runtime-environment
  for consumer products like cell phones, pagers,
  etc

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Java Integrated Development Environments (IDE)

• Consists of text editor, compiler, debugger, and
  other utilities integrated into a package
• Current popular Java IDEs include
• 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

• javac is used to compile Java programs
• E.g. javac Hello.java
• A .class file is created if no are found
• java is used to run Java programs
• E.g. java Hello
• Two types of errors (bugs) are
• Syntax errors mistakes that violate the rules
  of the programming language
• Logical errors mistakes that cause programs to
  produce erroneous results