HISTORY OF JAVA

JAVA

• Father of Java: James GasolineEXPANSIONS:• API-Application Programming Interface• SDK-Software Development Kit• JVM-Java virtual machine

History of Java• 1990 oak : To control microprocessors Embedded in customer item• Oak needed to be

– Platform independent– Extremely reliable– Compact

• 1993: Java – Internet and web exploration– Internet application

• 1994: Hot Java Browser• 1995: java1. 0

VERSIONS OF JAVA

• 1995 version 1.0:– The Java development kit was released for free by

the sun– 8-packages 212-classes– Microsoft and other companies licensed Java

• 1997 version 1.1:– 23 -packages 504-classes– Improvement include better event handling inner

classes , improved jvm

– Microsoft developed its own 1.1 compatible Java virtual machine for internet explorer

– Many browsers in use are still compatible only with 1.1

1999 version 1.2: -It is also called as the Java 2 platform -59 packages 1520 classes -Code & tools distributed as the SDK

-A Java foundation class based on swings for improved graphics and user interfaces

– Collection API included list sets and hash map

2000 VERSION 1.3: - 76 packages 1842 classes

- Java sound 2002 VERSION 1.4:

- 135 PACKAGES 2991 classes - Improved I , xml support etc..,

2004 VERSION 5.0 (1.5): - 165 packages over 3000 classes

- Faster startup metadata formatted output

– Generic to operate on objects of various types

2006 JAVA SE 6:– Scripting language support

2011 JAVA SE 7:– JVM support for dynamic language– String in switch– Allowing underscores in numeric literals

FUTURE RELEASES:JAVA SE 8: – LAMBDA OPERATOR is expected in summer 2013

JAVA SE 9:– Under planning

PACKAGES

• Each class has different methods is called packages

FEAUTURES OF JAVA TECHNOLOGY

PLATFORM INDEPENDENT:– Write once run anywhere

OBECT ORIENTED:– No coding outside of class definitions including

main ()– An extensive class library available in the core

language packages

COMPILER AND INTERPRETER:– Code is compiled to byte codes that are

interpreted by a JVM– This provides portability to any machine for which

a virtual machine has been written – The two steps of compilation and interpretation

allow for extensive code checking and improved security

ROBUST:– Exception handling built-in strong type checking

Several dangerous features of c & c++– No memory pointers– No pre processor– Garbage collector

AUTOMATIC MEMORY MANAGEMENT: – Automatic garbage collection memory

management handled by the JVM

SECURITY:– No memory pointers– Programs run inside the virtual machine sandbox

CODE PATHOLOGIES REDUCED BY:Byte code verifier:– Checks classes after loading

Class loaders:– Confines object of unique namespace

Security manager:– Determines what resources a class can access

JavaSource(. Java)

Java compiler

Java byte code

(. Byte)

Java byte code move

locally or through

the network

Class loader byte codes

Verifier

Java class libraries

Java interpreter

Just in time

compiler

Run time system

Operating system

Hardware

Differencec

• Focus on logic

• Procedure or structure oriented

• Top – down approach (Based on variable declaration)

c++

• Focus on both logic and data

• Object oriented programming language

• Bottom – top approach(Variable declaration

C++

• Partially object oriented language

• Pointers concept and Preprocessor are available

• Operator overloading is available

• Platform dependent

• A destructor is used to free the memory

• The compiler is present

JAVA• Purely object oriented

language

• Pointers concept and Preprocessor is not available

• Operator overloading is not available

• Platform independent

• Automatic garbage collection

• Both compiler and interpreter is present

Markup language

• HTML, XML

• Design based language

Programming language

• C, C++, JAVA etc..,

• Logic based language

XML• User defined tags

• Focused on data storage

• Case sensitive

HTML• Predefined tags

• Focused on design

• Non case sensitive

Difference between function member function and method

Function:• Independent calling (in c)Member function:• Partially dependent on object (in c++)(Members of class)Methods:• Fully dependent on object (Java)

Version 1.7 (string in switch)Import Java. Io. *;Class strswitch{Public static void main(string g[]){String s=“aaa”;Switch (s){Case “aaa”:

system.out.println(“from aaa”);Case “bbb”:

system.out.println(“from bbb”);Default:

system.out.println(“from default”);}}}

Output

from aaa

Integer literal

Import java.io.*;Class intliteral{Public static void main(string g[]){int a=12_78_56;System.out.println(“a=“+a);}}

Output

a=127856

Special Keywords in Java

• Static• Final• Volatile• Transient• Strictfp• Assert• Byte• Native• Boolean

Final:– Final is also like constant the give value can not change

throughout the program

Transient:– Used within a certain period of time So it's not used

more

Strictfp:– Display the exact result in a float

Assert:– Implementing our assumption

Native:– A program created in c can be accessed in Java

Byte:– Between range (-128 to 0 to 127)– Eg: byte b=123 is accepted

Byte b=129 is not accepted

Boolean:– Assigning true or false to a statement or block

Static and Volatile

Static :– A common memory allocation

Volatile:– Share the value

Example for static and volatile

Eg Program:Class samp{int a;Static int b;Volatile int c;}{Samp s1.new samp;Samp s2.new samp;Samp s3.new samp;}

Static memory allocation

a=1 ,b=2 ,c=3 s1 s2 s3ac b (b is declared as static so it is

used in common)

1 0 0

3 3 3

2

Volatile memory allocation

a=1 ,b=2 ,c=3 s1 s2 s3a c (volatile value will be

shared among the object) b

1 0 0

3 3 3

2

Java literalsInteger literal:Eg: int a=10;

int b=010;In integer literal if the first value is ‘0’ compilerwill take that as octal value.Perform the operation and display the outputOutput:8

int a=1;int b=2;int c=0x10; In integer literal if the first value is ‘0x’ compilerwill take that as hexadecimal value.Perform the operation and display the outputOutput:16

Character literals

Declarations:Char c=’p’;Char c=98;Char c=‘\n’; ”\0 is not used in java”Char c=‘\u0009’; (unicode)

Float literals

Declaration:Float f=12.56f;Float f=12.; (‘f’ no need compiler will take that

as 12.0)Bytes =4;Maximum digits =6Double:double d=75.76835457786(maximum range is

not defined)

String literalsstring s=“erode”;String s=“ero\bde”(o/p:erde(since /b is defined

as backspace))Eg:int a=10;int b=20;int c=30;string s=“hai”;s.o.p(“a+b+c+s”);s.o.p(“a+b+s+c”);s.o.p(“a+s+b+s”);

output

60hai30hai3010hai2030(still it finds the string it will add the

content or numbers)