1. Java Environment (CSS444)
Introduction
Object Oriented Programming Concepts
Basics for Java Applications
Basics for Java Applets
Control Structures
Methods
Arrays
Object Oriented Programming
Inheritance, Superclasses, Subclasses, Polymorphism, Abstract and concrete classes
Strings and Characters
Exception Handling
Files and Streams
Java Database Connectivity

2. Chapter 1 - Introduction to Computers, the Internet, and the World Wide Web
Outline
1.1 Introduction
1.3 Computer Organization
1.4 Evolution of Operating Systems
1.5 Distributed and Client/Server Computing
1.6 Machine Languages, Assembly Languages and High-Level Languages
1.8 History of Java
1.9 Java Class Libraries
1.10 Other High-Level Languages
1.11 Structured Programming
1.13 Basics of a Typical Java Environment
1.14 General Notes about Java and This Book

3. 1.1 Introduction Java Powerful, object-oriented language
Fun to use for beginners, appropriate for experienced programmers
Language of choice for Internet and network communications
Free implementation at

4. 1.3 Computer Organization
Six logical units in every computer
Input unit
Gets information from input devices (keyboard, mouse)
Output unit
Gets information (to screen, to printer, to control other devices)
Memory unit
Rapid access, low capacity, stores input information
Arithmetic and logic unit (ALU)
Performs arithmetic calculations and logic decisions
Central processing unit (CPU)
Supervises and coordinates the other sections of the computer
Secondary storage unit
Cheap, long-term, high-capacity storage, stores inactive programs and data

5. 1.4 Evolution of Operating Systems
Batch processing
Do only one job or task at a time
Operating systems
Manage transitions between jobs
Increased throughput - amount of work computers process
Multiprogramming
Many jobs or tasks sharing the computer resources
Timesharing
Runs a small portion of one user’s job then moves on to service the next user
Programs appear to be running simultaneously

6. 1.5 Distributed and Client/Server Computing
Distributed computing
Organization has a Local Area Network (LAN)
Computers linked to it
Computing distributed over the LAN, rather than at one central location

7. 1.5 Distributed and Client/Server Computing
File servers offer common store of programs that client computers access
C and C++ popular for writing operating systems, networking, and distributed client/server applications
Java used for Internet-based applications

8. 1.6 Machine Languages, Assembly Languages and High-Level Languages
Types of programming languages
Machine languages
Strings of numbers giving machine specific instructions
Example:
Assembly languages
English-like abbreviations representing elementary computer operations (translated via assemblers)
LOAD BASEPAY
ADD OVERPAY
STORE GROSSPAY

9. 1.6 Machine Languages, Assembly Languages and High-Level Languages
Types of programming languages
3. High-level languages
Similar to everyday English and use mathematical notations (translated via compilers)
Example:
grossPay = basePay + overTimePay

10. 1.8 History of Java Java Based on C and C++
Originally developed in early 1991 for intelligent consumer electronic devices
Market did not develop, project in danger of being cancelled
Internet exploded in 1993, saved project
Used Java to create web pages with dynamic content
Java formally announced in 1995
Now used to create web pages with interactive content, enhance web servers, applications for consumer devices (pagers, cell phones)...

11. Two parts to learning Java
1.9 Java Class Libraries
Java programs
Consist of pieces called classes
Classes contain methods, which perform tasks
Class libraries
Also known as Java API (Applications Programming Interface)
Rich collection of predefined classes, which you can use
Two parts to learning Java
Learning the language itself, so you can create your own classes
Learning how to use the existing classes in the libraries

12. 1.10 Other High-Level Languages
A few other high-level languages have achieved broad acceptance
FORTRAN (FORmula TRANslator)
Scientific and engineering applications
COBOL (COmmon Business Oriented Language)
Used to manipulate large amounts of data
Pascal
Intended for academic use
BASIC
Developed in 1965 as a simple language to help novices

13. 1.11 Structured Programming
Disciplined approach to writing programs
Clear, easy to test and debug, and easy to modify
Pascal designed to teach structured programming in universities
Not used in industrial or commercial applications
Multitasking
Specifying that many activities run in parallel
C and C++ only allow one activity to be performed at a time
Java allows multithreading, where activities can occur in parallel

14. 1.13 Basics of a Typical Java Environment
Java Systems
Consist of environment, language, Java Applications Programming Interface (API), Class libraries
Java programs have five phases
Edit
Use an editor to type Java program
vi or emacs, notepad, Jbuilder, Visual J++
.java extension
Compile
Translates program into bytecodes, understood by Java interpreter
javac command: javac myProgram.java
Creates .class file, containing bytecodes (myProgram.class)

15. 1.13 Basics of a Typical Java Environment
Java programs have five phases (continued)
Loading
Class loader transfers .class file into memory
Applications - run on user's machine
Applets - loaded into Web browser, temporary
Classes loaded and executed by interpreter with java command
java Welcome
HTML documents can refer to Java Applets, which are loaded into web browsers. To load,
appletviewer Welcome.html
appletviewer is a minimal browser, can only interpret applets

16. 1.13 Basics of a Typical Java Environment
Java programs have five phases (continued)
Verify
Bytecode verifier makes sure bytecodes are valid and do not violate security
Java must be secure - Java programs transferred over networks, possible to damage files (viruses)
Execute
Computer interprets program one bytecode at a time
Performs actions specified in program
Program may not work on first try
Make changes in edit phase and repeat

17. Editor
Program is created in the editor and stored on disk.
Disk
Phase 1
Compiler
Disk
Compiler creates bytecodes and stores them on disk.
Phase 2
Primary
Memory
Class Loader .
Phase 3
Class loader puts bytecodes in memory.
Disk
Primary
Memory
Bytecode Verifier .
Phase 4
Bytecode verifier confirms that all bytecodes are valid and do not violate Java’s security restrictions.
Interpreter
Primary
Memory
Interpreter reads bytecodes and translates them into a language that the computer can understand, possibly storing data values as the program executes.
Phase 5 .

18. 1.14 General Notes about Java and This Book
Powerful language
Programming notes
Clarity - Keep it Simple
Portability - Java very portable, but it is an elusive goal
Performance
Interpreted programs run slower than compiled ones
Compiling has delayed execution, interpreting executes immediately
Can compile Java programs into machine code
Runs faster, comparable to C / C++

19. 1.14 General Notes about Java and This Book
Just-in-time compiler
Midway between compiling and interpreting
As interpreter runs, compiles code and executes the program in the machine language rather than reinterpreting.
Not as efficient as full compilers
A full compiler is being developed for Java
Integrated Development Environment (IDE)
Tools to support software development
Several Java IDE's are as powerful as C / C++ IDE's
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