1. The University of Akron Summit College
2440: 160 Java Programming
Introduction to Computers & Java
Professor: Enoch E. Damson

2. Parts of an Information System
Hardware
Software
Procedures
Data
People
Introduction to Computers & Java

3. Introduction to Computers & Java
Hardware
Physical components of a computer
Consists of:
Input devices
Processor or Central Processing Unit (CPU)
Main memory
Secondary storage devices
Output devices
Introduction to Computers & Java

4. Introduction to Computers & Java
Input Devices
Collects data for the computer
Common devices include:
Keyboard
Mouse
Scanner
Digital camera
Introduction to Computers & Java

5. 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 computer’s operations
Arithmetic & Logic Unit (ALU) – performs mathematical operations
Introduction to Computers & Java

6. Introduction to Computers & Java
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
Introduction to Computers & Java

7. 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
Introduction to Computers & Java

8. Introduction to Computers & Java
Output Devices
Formats and presents processed data (information) to the outside world
Common devices include:
Monitors
Printers
Introduction to Computers & Java

9. Introduction to Computers & Java
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
Introduction to Computers & Java

10. Introduction to Computers & Java
Procedures
Rules or guidelines for people to follow when using software, hardware, and data
Guidelines are documented in manuals
Introduction to Computers & Java

11. Introduction to Computers & Java
Data
Raw facts entered into the computer system for processing
Processed to produce information
Introduction to Computers & Java

12. Introduction to Computers & Java
People
Making people more productive is what computers are all about
Users include:
Analysts
Designers
Developers
End-users
Introduction to Computers & Java

13. Introduction to Computers & Java
Computer Program
Set of instructions that enables the computer to solve a problem or perform a task
The instructions are called algorithms
A computer’s CPU can only process algorithms written in machine language – consisting of binary numbers (0s and 1s)
E.g
Each different type of CPU has its own machine language
Algorithms written with programming languages are much easier to understand
Introduction to Computers & Java

14. Introduction to Computers & Java
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
Introduction to Computers & Java

15. 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
Introduction to Computers & Java

16. Program Development (Programming) Cycle…
Creating program specifications – the requirements the application must meet
Introduction to Computers & Java

17. 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
Introduction to Computers & Java

18. 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
Introduction to Computers & Java

19. 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)
Introduction to Computers & Java

20. 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
Introduction to Computers & Java

21. 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.
Introduction to Computers & Java

22. 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
Introduction to Computers & Java

23. 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
Introduction to Computers & Java

24. 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 programmer’s 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 s, 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
Introduction to Computers & Java

25. 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
Introduction to Computers & Java

26. 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
Introduction to Computers & Java

27. Methods of Programming
Two primary methods of programming are:
Procedural – creates programs made up of variables and procedures
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)
Object – a software entity with attributes (fields) and procedures (methods)
Class – specifies the attributes and methods of objects
Introduction to Computers & Java

28. Principles of Object-Oriented Programming (OOP)
Encapsulation – grouping data (fields, methods, etc) into a single object
Information Hiding (Abstraction) – hiding an object’s data from other objects
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
There are 2 types of polymorphism: overloading and overriding
Introduction to Computers & Java

29. Introduction to Computers & Java
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
Introduction to Computers & Java

30. Introduction to Computers & Java
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
Introduction to Computers & Java

31. Introduction to Computers & Java
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 computer’s memory
Introduction to Computers & Java

32. 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
Introduction to Computers & Java

33. 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
Introduction to Computers & Java

34. Introduction to Computers & Java
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
Introduction to Computers & Java

35. Java Integrated Development Environments (IDE)
Consists of text editor, compiler, debugger, and other utilities integrated into a package
Current popular Java IDEs include:
Eclipse (
NetBeans (
IntelliJ IDEA (
jGRASP (
Introduction to Computers & Java

36. 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
Introduction to Computers & Java