Transcript Chapter 1 – Introduction to Computers, the Internet, and

ICT 6007
Visual and Internet Programming
using JAVA
Mohammad Tanvir Alam
Lecturer
IICT,BUET
Home page: http://teacher.buet.ac.bd/teacher/mtanviralam/
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Reference
Book
• Java How to Program (5th or 6th edition)
Deitel & Deitel
• Programming Tools
– Java 2 Standard Edition
• IDE
– JBuilder 7.0 or later
– Kawa 4.0 or later
Chapter 1
Outline
History of C++
History of Java
Java Class Libraries
BASIC, Visual Basic, Visual C++, C# and .NET
Basics of a Typical Java Environment
Thinking about Objects
Machine Languages, Assembly Languages
and High-Level Languages
• Machine language
– “Natural language” of computer component
– Machine dependent
• Assembly language
– English-like abbreviations represent computer operations
– Translator programs convert to machine language
• High-level language
– Allows for writing more “English-like” instructions
• Contains commonly used mathematical operations
Compiler VS Interpreter
• Compiler
– Compiler convert to whole program to machine language
• Interpreter
– Execute high-level language programs without compilation
line by line
History of C++
• C++
– Evolved from C
– Provides object-oriented programming capabilities
• Objects
– Reusable software components that model real-world items
History of Java
• Java
– Originally for intelligent consumer-electronic devices
– Then used for creating Web pages with dynamic content
– Now also used for:
• Develop large-scale enterprise applications
• Enhance WWW server functionality
• Provide applications for consumer devices (cell phones, etc.)
Java Class Libraries
• Classes
– Include methods that perform tasks
– Used to build Java programs
• Java contains class libraries
– Known as Java APIs (Application Programming Interfaces)
BASIC, Visual Basic, Visual C++, C# and
.NET
• BASIC
– Beginner’s All-Purpose Symbolic Instruction Code
• Visual Basic .NET
– Framework Class Library (FLC)
• Visual C++
– Microsoft Foundation Classes (MFC)
• C#
– C-Sharp
• .NET
– .NET platform
Basics of a Typical Java Environment
• Java programs normally undergo five phases
– Edit
• Programmer writes program (and stores program on disk)
– Compile
• Compiler creates bytecodes from program
– Load
• Class loader stores bytecodes in memory
– Verify
• Verifier ensures bytecodes do not violate security requirements
– Execute
• Interpreter translates bytecodes into machine language
Phase 1
Editor
Disk
Program is created in
an editor and stored
on disk in a file ending
with .java.
Phase 2
Compiler
Disk
Compiler creates
bytecodes and stores
them on disk in a file
ending with .class.
Primary
Memory
Phase 3
Class Loader
Disk
Phase 4
Bytecode
Verifier
. ..
..
.
Class loader reads
.class files
containing
bytecodes from
disk and puts
those bytecodes
in memory.
Primary
Memory
Bytecode verifier
confirms that all
bytecodes are valid
and do not violate
Java’s security
restrictions.
. ..
..
.
Primary
Memory
Phase 5
Interpreter
. ..
..
.
Interpreter reads
bytecodes and
translates them into
a language that the
computer can
understand,
possibly storing
data values as the
program executes.
Fig. 1.1 Typical Java environment.
Thinking About Objects (cont.)
• Objects
– Reusable software components that model real-world items
– Look all around you
• People, animals, plants, cars, etc.
– Attributes
• Size, shape, color, weight, etc.
– Behaviors
• Babies cry, crawl, sleep, etc.
Thinking About Objects (cont.)
• Object-oriented design (OOD)
– Models real-world objects
– Models communication among objects
– Encapsulates attributes and operations (behaviors)
• Information hiding
• Communication through well-defined interfaces
• Object-oriented language
– Programming in object oriented languages is called objectoriented programming (OOP)
– Java