Session1 - Introduction to Java-Final

8/22/2019 Session1 - Introduction to Java-Final

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Introduction to Java

Session 1


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Introduction to Java / 2 of 28

Objectives

Discuss Java in brief

Explore the types of Java programs Discuss what we can do with Java?

Examine the differences between Applets andApplications

Describe the Java Virtual Machine (JVM) Explore the features of some IDEs

Discuss the JDK and tools under it

Discuss future trends and technologies

Discuss the brief history of Java


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Introduction to Java

Java being secure, portable and platformindependent was found to be capable ofaddressing large scale problems across the

Internet

Introduced in 1995 by Sun Microsystems

Objective was to develop a software forembedding in consumer electronic devices

Initially called Oak

Internet users had problems of portability and

platform independence


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What is Java?

A cross platform language

It is used for stand-alone applications, net

based programs and to program consumerdevices

For e.g.: cellular phones, palm pilots

An object-oriented programming language


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Java and the internet

Applets can respond to user input and actions

Programs on the Net are either static or

dynamic

Applets help develop dynamic programs

Applets run on Java enabled web browser


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Security issues (1)

This can be a potential risk for the users

system

An Applet has to be downloaded on the users

system before it can work

Hence, applets are restricted from accessing all

areas of the disk


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Security issues (2)

JVM generates byte codes as a result ofcompilation

Byte codes cannot be executed without the JVM

This control is exercised by the



Types of Java programs (1) Applets

Programs created specially to work with the

Internet

Displays an image GUI to accept user input



Types of Java programs (2) Command line applications

Java programs that run from a command prompt

and do not display any GUI screen



Types of Java programs (3) GUI Applications

Java programs that run stand-alone and accept

user input through a GUI based screen



Types of Java programs (4)

Client sends request which is processed by theserver

The server side APIs extend capabilities of

standard APIs and are known as Servlets Also called server side applets

For e.g. HTML form processing, processdatabases and perform server side transactions

Servlets

Suitable for web based n-tier application

development



Types of Java programs (5)

A programmer can create his/her own packages

or use the built-in packages

java.awt, java.io and java.applet are some examples

Database applications Uses JDBC API for database connectivity

Programs can be either applets or application

Packages

Class libraries in Java



What can we do with Java?

Colorful scrolling banner for web pages

Interactive quiz A program that plays audio, displays a banner and

animates images at the same time

Interactive games that can run as stand alone or

deployed on the web

One can develop:

Create a wide variety of applications from a

simple computation program to complex

distributed application



Difference between

Applets and Applications (1)

Do not need a browser

to execute

These run within JVM

Executed in a java

compatible web

browser

Applets load and run on

a Java-enabled web

browser

Applications Applets


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Difference between


Manages its own flow of

execution

No restrictions about

reading or writing

from/to the local filesystem

Flow of execution is

partly managed by thebrowser context

Cannot read/write

from/to the local file

system

Applications Applets


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Similarities in


Both can use the Abstract Windowing Toolkit

(AWT)

Both need to use the standard Java class

libraries


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Java Virtual Machine (JVM)

Java code can run on any platform by using JVM

JVM normally reads and executes Java

statements one at a time

JVM is responsible for platform independence and

small size compiled code

Recognizes only a particular binary format called

a class file

Has an interpreter component that enablescommunication between Java byte code and a

computers operating system


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Visual development tools

Simplifies the software development process

Includes class browser for viewing and

navigating through the class hierarchy Includes a source code editor that helps code

programs

Helps in quick and efficient development of

Java applications and applets


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Some visual development tools

Borland Jbuilderfrom Borland/Inprise Includes an integrated editor, debugger, compiler, visual

designer, wizards and sample applications

Forte for Java, Community Edition from SunMicrosystems Integrated visual design, editing, compilation and debugging

capabilities to create applets and applications

Visual Age for Java from IBM Works with existing databases, applications and transactions


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Java Development Kit (JDK)

Basically a set of command line tools

Three major releases are :

Java 1.0 first release

Java 1.1 1997 release

Java 2 latest release

Freely available at Suns official website

Contains the software and tools needed tocompile, debug and execute applets andapplications


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Tools under JDK (1)

Syntax : javac [option] source

Source files end with extension .java

Options can include

-classpath

-d

-g

-o

-verbose

javac : compiler used to compile Java source

code


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Tools under JDK (2)

java [option] classname [arguments]

Options can include

-classpath

-Dname name -help

-v orverbose

-X

java: interpreter used to execute Java byte

codes


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Tools under JDK (3)

javadoc : This is the Java documentation tool

Generates detailed documentation in HTML formfor any .java source code or package

appletviewer: Used to view and test applets

Syntax : appletviewer [options] url


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New features in Java2 (1)

Drag and Drop interactively transferring

information across different applications and

from one part of a programs interface to

another

Swing new set of classes and interfaces

used to create an advanced GUI


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New features in Java2 (2)

Java Sound totally new set of features

pertaining to Javas audio features

RMI Remote Method Invocation allows

applications to call objects located at remote

sites and communicate with them

Java 2D API set of classes for advanced

2D graphics and imaging


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Present Java technologies (1)

Support for distributed computing in the formof features such as RMI

Database management support in the form ofJDBC

Reusable software components in the form ofJavaBeans

Creation and deployment of applications that

can run on any operating system


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Present Java technologies (2)

Java 2 Enterprise Edition (J2EE) which

includes :


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Future trends

Miniature devices such as Palm pilots andmobile phones are equipped with a features

such as email, gaming options and manyothers

They are based upon Java 2 Micro Edition(J2ME)

New products in the area of embedded

technologies for consumer devices by making

use of mobile computing

Documents

Session1 - Introduction to Java-Final