An intoduction to Java Technology

• Introduction to JAVA
• Java Platforms
• Java is Everywhere
• Version in Details
• James Gosling at a Glance
• Java Quick Facts
• What is Java?
• Java Development Kit (JDK)
• How does JVM works?
• Running on Different Platforms
• Features of Java
• Types of Java Program
• Applets and Applications
• Key Benefits & Features of Java

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Introduction to JAVA

Java – is an object-oriented programming language that is platform independent (the same Java program runs on all hardware platforms without modification).

Java – is a programming language originally developed by Sun Microsystems and released in 1995 as a core component of Sun’s Java platform.

Java Platforms

Java is generally thought of in terms of four platforms.

• Standard Edition (SE) or JavaSE
• Enterprise Edition (EE) or JavaEE
• Micro Edition (ME) or JavaME
• Java Fx

J2SE – Java 2 Standard Edition Overview

• Java Platform, Standard Edition (also known as Java 2 Platform) lets you develop and deploy Java applications on desktops and servers, as well as today’s demanding Embedded and Real-Time environments.
• Java SE includes classes that support the development of Java Web Services and provides the foundation for Java Platform, Enterprise Edition (Java EE).

JDK=Java Tools + JRE

JRE=JavaSE API + JVM

Basic Tools

Java Tool	Description	Example
Javac	The compiler for the Java programming language.	eg. C:\>javac Hello.java
Java	The launcher for Java applications.	eg. C:\>java Hello
Javadoc	API documentation generator.	eg. C:\>javadoc Hello.java
Javap	Class file disassembler	eg. C:\>javap java.lang.String
Appletviewer	Run and debug applets without a web browser.	eg. C:\>appletviewer xyz.html
Jar	Manage Java Archive (JAR) files.	eg. C:\>jar -cvf xyz.java *.class
jdb	The Java Debugger, jdb, is a simple command-line debugger for Java classes. It is a demonstration of the Java Platform Debugger Architecture that provides inspection and debugging of a local or remote Java Virtual Machine.	eg. C:\> jdb MyClass

Example of jar Command

Creating Jar File

F:\>jar -cvf xyz.jar *.class

added manifest
adding: abc.class(in = 404) (out= 277)(deflated 31%)
adding: Calculator.class(in = 894) (out= 467)(deflated 47%)
adding: demo.class(in = 775) (out= 463)(deflated 40%)
adding: gender.class(in = 758) (out= 452)(deflated 40%)
adding: JavaApplication1.class(in = 1074) (out= 612)(deflated 43%)
adding: MethodOverloading.class(in = 455) (out= 326)(deflated 28%)
adding: test.class(in = 302) (out= 237)(deflated 21%)
adding: xyz.class(in = 399) (out= 249)(deflated 37%)

Extracting Jar File

F:\abc>jar xvf f:\xyz.jar
created: META-INF/
inflated: META-INF/MANIFEST.MF
inflated: abc.class
inflated: Calculator.class
inflated: demo.class
inflated: gender.class
inflated: JavaApplication1.class
inflated: MethodOverloading.class
inflated: test.class
inflated: xyz.class

Example for Double clickable jar file

MANIFEST.MF

Manifest-Version: 1.0
Created-By: 1.6.0_04 (Sun Microsystems Inc.)
Main-Class: xyz.hello

hello.java

package xyz;
import javax.swing.*;
class hello 
{
	public static void main(String[] args) 
	{
		JFrame f;
		f=new JFrame("Hello");
		f.getContentPane().add(new JLabel("Hi,Anuj!! I am james Bond."));
		f.setSize(400,200);
		f.setVisible(true);
	}
}

Creating double clickable Jar File

F:\>javac -d . hello.java
 
F:\>jar cfm first.jar MANIFEST.MF xyz/hello.class

Now click double on created jar file.

OR

Running Jar File on command prompt

F:\>java -jar first.jar

Example for jdb java debugger

F:\>javac demo.java
F:\>jdb demo
Initializing jdb ...
> run
run demo
Set uncaught java.lang.Throwable
Set deferred uncaught java.lang.Throwable
>
VM Started: hello
15

The application exited
F:\>

Brief History of Java

• In 1990, Sun Microsystems began an internal project known as the Green Project to work on a new technology.
• In 1992, the Green Project was spun off and its interest directed toward building highly interactive devices for the cable TV industry. This failed to materialize.
• In 1994, the focus of the original team was re-targeted, this time to the use of Internet technology. A small web browser called HotJava was written. Oak was renamed to Java after learning that Oak had already been trademarked.
• In 1995, Java was first publicly released.
• In 1996, Java Development Kit (JDK) 1.0 was released.
• In 2002, JDK 1.4 (codename Merlin) was released, the most widely used version.
• In 2004, JDK 5.0 (codename Tiger) was released.
• JDK 1.6 (Mustang) in 11 Dec 2006
• JDK 1.7 (Dolphin) in July 7, 2011
• Java 8 (Spider) is released on 18 March 2014

J2EE Java 2 Enterprises Edition Overview

• Java Platform, Enterprise Edition (Java EE) builds on the solid foundation of Java Platform, Standard Edition (Java SE) and is the industry standard for web applications.
• The SDKs contain Sun Java System Application Server (Sun’s supported distribution of GlassFish) and provide support for Java EE 5 specifications.

J2ME Java 2 Micro Edition Overview

• Java Platform, Micro Edition (Java ME) is a set of technologies and specifications developed for small devices like pagers, mobile phones, and set-top boxes.
• Java ME uses smaller-footprint subsets of Java SE components, such as smaller virtual machines and defines a number of APIs that are specifically targeted at consumer and embedded devices.

Java is Everywhere

Note : JAVA is now open source!!!

Version in Details

Version	Code Name	Release Date
JDK 1.0	Oak	January 23, 1996
JDK 1.1	Major additions included	19 Feb 1997
JDK 1.2	Playground	8 Dec 1998
JDK 1.3	Kestrel	08 May 2000
JDK 1.4	Merlin	06 Feb 2002
JDK 1.5	Tiger	30 Sep 2004
JDK 1.6	Mustang	11 Dec 2006
JDK 1.7	Dolphin	July 7, 2011
JDK 8	Spider	March 2014
JDK 9		21 Sep 2017
JDK 10	AKA Java 18.3	in March 2018 and 18.3

JDK 1.0

In 1996, Java Development Kit (JDK) 1.0 was released

JDK 1.1

• Consist of AWT Event Model, Inner Classes, Java Beans, JDBC and RMI

JDK 1.2 – CodeName : Playgroung

Major additions included :-

• “Strictfp” keyword
• Reflection API
• Sun’s JVM – JIT Compiler for the first time
• Java Plugins
• Java IDL – Corba interoperability
• Collections framework

JDK 1.3 Code Name : Kestrel

Most notable changes were:-

• HotSpot JVM (Revised)
• RMI was modified to support optional compatibility with CORBA
• Java Sound
• JNDI – Java Naming and Directory Interface included in core libraries

JDK 1.4 Code Name : Merlin

Major changes included

• Assert keyword
• Regular Expressions modeled
• Exception Chaining – allows an exception to encapsulate original lower-level exception
• IPV6 support
• Non blocking NIO
• Logging API
• Integrated XML Parser and XSLT Processor
• Image I/O API
• Integrated Security & cryptography extensions

JDK 1.5 Code Name : Tiger

New language features :-

• Generics – Provides compile-time (static) type safety for collections and eliminates the need for most typecasts (type conversion)
• Metadata-Annotations – allows language constructs such as classes and methods to be tagged with additional data, which can then be processed by metadata-aware utilities.
• Autoboxing/Unboxing
• Enumerations- with “enum” keyword
• Swing – New L&F(Look & Feel) – called ‘Synth’
• Varargs – The last parameter of a method can now be declared using a type name followed by three dots.
• Enhanced ‘for’ loop
• Fix the previously broken semantics of the Java Memory Model, which defines how threads interact through memory
• Automatic stub generation for RMI Objects

JDK 1.6 Code Name : Mustang

Notable Elements:-

Release nomenclature – Sun replaced ‘J2SE’ with JavaSE & dropped the ‘.0’ from the version number; Internal numbering for developers remains 1.6.0

Major changes:-

• Improved Web Service
• JDBC 4.0
• Java Compiler API – allowing a java program to select & invoke a java compiler programmatically
• Integration of SwingWorker in the API, table sorting and filtering & true swing double buffering

JDK 1.7 Code Name : Dolphin

New builds include:-

• JVM support for dynamic languages – following the prototyping work currently done on Multi Language Virtual Machine.
• New Library for parallel computing on Multi-core processors
• Superpackages – which are a way to define explicitly in a library or module which classes will be visible from outside of the library
• Swing Application Framework.

JDK 8, JDK 9, JDK 10 (March 2018) has been released also.

James Gosling

• James Gosling is generally credited as the inventor of the Java programming language
• He was the first designer of Java and implemented its original compiler and virtual machine
• He is also known as the Father of Java
• He was the Chief Technical Officer of Sun Microsystems.

Java Quick Facts

• 4.5 million Java developers, the largest community of software developers
• 75% of professional developers in the world use Java
• 1.75 billion devices run in Java
• 825 million Java-enabled smart cards
• 579 million Java-enabled mobile devices
• 635 Java-enabled phone models
• 700 million desktops with Java software
• 220,000 downloads of JDK 1.1 in just 3 weeks, 2 million after a year
• 2 million downloads for J2EE SDK
• JavaOne draws 20,000 becoming the world’s largest developer conference
• Over 400 Java user groups established worldwide
• Java runs on consumer and embedded devices more than any other software
• The software that powers the Mars Rover

Java is Everywhere!

What is Java?

It is a multi-platform, network-centric, object-oriented programming language.

Multi-platform

• It can run on almost any computer platform

Network-centric

• Designed with network in mind – “the network is the computer”
• Designed for building applications for the Internet

Object-oriented

• It incorporates object-oriented programming model

Java Development Kit (JDK)

Java Development Kit (JDK)

• Is a set of Java tools for developing Java programs
• Consists of Java API, Java Compiler, and JVM

Java Application Programming Interface (API)

• Is prewritten code, organized into packages of similar topics

Java Virtual Machine (JVM)

• Is an execution engine that runs compiled Java byte code

How does JVM work?

A Java program is written
The program is compiled
A class file is produced containing byte codes.
The bytecodes are interpreted by the JVM
The JVM translates bytecodes into native machine code

Running on Different Platforms

Features of Java

• Is simple to learn
• Follows the Object-oriented approach
• Can access data across networks
• Is both interpreted and compiled
• Programs are robust and reliable
• Programs are portable
• Programs are more secure
• Programs are faster
• Supports multithreading
• Programs are dynamic in nature

Types of Java Programs

Applications

• are programs that do not need a browser for execution

Applets

• are programs that run on a Web page

Servlets

• are programs that extend the functionality of a server

Packages

• contain collection of classes and helps to organize classes.

Applets and Applications

Applications

• are programs that are executed using the MS-DOS prompt
• may or may not have a graphical user interface
• are usually character based console applications
• have more security privileges than applets
• reside on the local hard disk of the machine

Applets

• are programs that execute inside a Web page
• have to be downloaded before they can be executed
• have a graphical user interface
• cannot access the resources of the local machine

Key Benefits & Features of Java

Write Once, Run Anywhere

• Java is portable and platform independent

Network-centric

• Can work with resources across a network and multi-tier architectures

Object-oriented

• A Java program models a set of objects interacting with each other

Robust

• Strong type checking
• Exception handling mechanism
• Automatic memory management

Multithreaded

• A Java application can run several different processes called “threads” simultaneously

Security

• Can download remote code over a network and run it in a secure environment
• Security levels and restrictions are highly configurable