1.
Introduction
to
Java

2.
• Today Java , is one of the most popular programming
language which is used in critical applications like…
 web based applications
Embedded applications
 android mobile application.
Introduction

3.
• Lets have a look in history of Java…
• Java was developed by James Gosling from Sun Microsystems in 1995.
• Introduced as an object-oriented language for general-purpose business
applications and for interactive, Web-based Internet applications.
• The goal was to provide platform-independent alternative to C++. In other
terms it is architecturally neutral, which means that you can use Java to
write a program that will run on any platform or device.
• Instead, Java runs on a Java Virtual Machine (JVM).
History & Evolution

4.
• James Gosling ,Mike Sheridan and Patrick Naughton initiated the
green project in June 1991.
• Originally designed for small , embedded systems in electronic
appliances like set-top boxes.
• It was initially called as Oak and later on renamed as “Java” in 1995.
• Originally developed by James Gosling at Sun Microsystems in
1995.
• JDK 1.0 released in 1996.
History and Evolution

5.
History of Java Releases
Java Version/Code Name
Release Date
Important Features/Code Name
JDK 1.0 (Oak)
23rd Jan 1996
Initial release
JDK 1.1
19th Feb 1997
Reflection , JDBC , Inner Classes
,RMI
J2SE 1.2 (Playground)
8th Dec 1998
Collection , JIT, String memory map
J2SE 1.3 (Kestrel)
8th May 2000
Java Sound , Java Indexing ,JNDI
J2SE 1.4 (Merlin)
6th Feb 2002
Assert , regex, exception chaining
J2SE 5.0 (Tiger)
30th Sept 2004
Generics ,autoboxing ,enums
Java SE 6.0 (Mustang)
11th Dec 2006
JDBC 4.0 , Java compiler API ,
Annotations
Java SE 7.0 (Dolphin)
28th July 2011
String in switch case ,exception
handling new way

6.
Simple:
A Java programmer does not need to know the internal
functioning of Java, such as how memory is allocated to data.
Object-oriented:
Java supports the object-oriented approach to develop
programs.
Compiled and interpreted:
The Java programs are first compiled and then interpreted.
After the program is compiled, it is converted to a bytecode.
The Java Virtual Machine (JVM) then interprets this bytecode
into the computer code and runs it.
Portable:
Refers to the ability of a program to run on any platform without
changing the source code of a program.
Features of Java Environment

7.
•
The following figure shows how the Java bytecode and the JVM together
make Java programs portable on different platforms.
Features of Java Environment

8.
Distributed:
Java is designed for the distributed environment of the Internet
because it supports the various Internet protocols, such as
Transmission Control Protocols and Internet Protocol (TCP/IP).
Secure:
Java has built-in security features that verify that the programs
do not perform any destructive task, such as accessing the
files on a remote system.
Features of Java
Environment

9.
• Java technology provides language part along with architecture for
running applications.
• Java Architecture provides
• Portable
• high-performance
• robust runtime environment.
• Various Components of Java Architecture are :
• Java Programming Language and class file
• JVM
• Java Application Programming Interface (API)
Java Architecture

10.
• Java Runtime Environment contains JVM, class libraries and
other supporting components.
• Java source code is compiled into bytecode by Java compiler.
• This bytecode will be stored in class files.
• During runtime, this bytecode will be loaded, verified
and JVM interprets the bytecode into machine code which
will be executed in the machine in which the Java program
runs.
Java Runtime Environment (JRE)

11.
• A Java Runtime Environment performs the following main
tasks respectively.
• Loads the class
• This is done by the class loader
• Verifies the bytecode
• This is done by bytecode verifier.
• Interprets the bytecode
• This is done by the JVM
Java Runtime Environment (JRE)

12.
• Java programming language and class file:
• Java programs are saved with an extension, .java.
• A .java file is compiled to generate the .class file, which contains the
byte code.
• The JVM converts the byte code contained in the .class file to machine
object code.
• The JVM needs to be implemented for each platform running on a
different operating system.
Java Programming Lang. & Class file

13.
• Its an abstract Machine forms the base of Java Platform.
• Specification that provides runtime environment in which java byte code
can be executed.
• Available for many hardware and software.
• JVM performs:
•
•
•
•
Loads code
Verifies code
Executes code
Provide Runtime Environment
Java Virtual Machine (JVM)

14.
• Major Components of JVM
• Class Loader
• Byte code Verifier
• Just In Time (JIT) compiler
Java Virtual Machine

15.
Interpreter
Byte
Code
Class
Loader
Byte code
Verifier
JIT Compiler
Java Runtime Environment
Java Virtual Machine
Running
Program

16.
• Class Loader
• Class loader loads all the class files required to execute the
program.
• Byte code Verifier
•
•
•
•
Checks that code follows JVM specifications.
There is no unauthorized access to memory.
The code does not cause any stack overflows.
There are no illegal data conversions in the code such as float to
object references.
Components of JVM

17.
• JIT Compiler
• Used to improve performance.
• It translates byte code only the first time.
• If repeated execution of code is required , it is automatically
mapped to the corresponding native machine code.
• JIT make use of the machine code which is cached and stored.
Components of JVM

18.
Java Development Kit
• Package that provides the basic functionality of Java Language.
• Contains series of classes and methods
• Tools used to develop and execute java programs is known as JDK.
• It contains
•
•
•
•
Basic Tools( javac,java,javap,javadoc,appletviewer etc)
RMI tools (rmic,rmiregistry,rmid)
Security Tools (keytools,policytool etc.)
Java plug-in Tools

19.
Basic Tools
Description
Javac
Compiler for java language
Java
Launcher of java application
Javadoc
API documentation generator
Appletviewer
Run and debug applets without a web
browser
Jar
Manage java archive files
Javap
Class file dissassembler
Java Development Kit

20.
The Java API is a collection of software components that provide
capabilities, such as GUI.
The related classes and interfaces of the Java API are grouped
into packages.
The following figure shows how the Java API and the JVM forms
the platform for the Java programs on top of the hardware.
Java API

21.
• Java can be used to develop more dynamic programs.
• Leading programming language for wireless technology and real time
embedded programming for cell phones.
• Major Categories of java programs :
• Applets
• Applications
Type of Java Programs

22.
• Applets
• Small program embedded in a web page.
• Applets are downloaded over network and can make network
connections only to the host they are issued from.
• Graphical in nature and tends to contain controls like text field
, button label etc.
• Applications
•
•
•
•
Standalone programs written in java.
Invoked by using a JVM.
Can access the local file system.
Can execute on the server machine.
Types of Java Programs

23.
• Temporary Path Setting
• Open command prompt
• Copy the path of bin folder
• Write in command prompt
• Set path=c:Program
FilesJavaJdk1.6.0_03bin;
• Permanent Path Setting
• Right click on My Computer
• Select Properties > Advanced tab >
Environment variables >new tab of
user variables > write path in
variable name > write path of bin
folder in variable value > ok
Setting Path for JDK in Windows

24.
Java Program Life Cycle

25.
• Create a source document using any editor such as Notepad and save file as
.java
• For example: HelloWorld.java
• Compile the java file using “javac” command. Byte Code will be
generated on disk.
Javac HelloWorld.java
After Compilation
HelloWorld.class
• This byte code can run on any platform or device having JVM using
“java”
Command.
StepS are….

26.
class simple
{
public static void main(String args[])
{
System.out.println(“Hello Java”);
}
}
To Compile : javac simple.java
To Run
: java simple
Sample Java Program

27.
• class : Used to declare class in java.
• public : Access modifier which represents the visibility.
• static : Keyword for creating static method , so that we can access it
without creating object.
• void : Return type of main method , its doesn’t return anything.
• main : Represent the startup of the program
• String args[] : Used to store command line arguments.
Understanding Sample
Program

28.
Source Code
Program
Compiler
Byte code
Compilation Process
Compilation & Execution

29.
R
U
N
T
I
M
E
P
R
O
C
E
S
S
Class file
Class Loader
Byte Code Verifier
Interpreter
Runtime
Compilation & Execution

30.
Output Screen

31.
• Built-in support for multi-threading, socket communication, and memory
management (automatic garbage collection).
• Object Oriented (OO).
• Better portability than other languages across operating systems.
• Supports Web based applications (Applet, Servlet, and JSP) .
• Supports distributed applications (sockets, RMI, EJB etc.) and network
protocols (HTTP, JRMP etc.) with the help of extensive standardized
APIs (Application Programming Interfaces).
Advantages of Java Programming
Language