CORE JAVA

CORE JAVA
Invented and first implemented by Dennis Ritchie on a DEC PDP-11 running the UNIX operating system, C was the result of a development process that started with an older language called BCPL, developed by Martin Richards. BCPL influenced a language called B, invented by Ken Thompson, which led to the development of C

C is not good for lengthy programs so C++ is response to decrease the complexity of programs has driven the objects and communicated each others

C, C++ program for just about any type of CPU, to do so require a full C++ compiler targeted for that CPU. The problem is that compilers are expensive and time-consuming to create. “JAVA” was designed to solve a certain set of problems.

Byte code is a highly optimized set of instructions designed to be executed
by the Java run-time system, which is called the Java Virtual Machine (JVM).
JVM will differ from platform to plat form , all interpret the same Java byte code
Java program is interpreted also helps to make it secure. Because the execution of every Java program is under the control of the JVM. When the JIT compiler is part of the JVM, it compiles byte code into executable code in real time, on a piece-by-piece, demand basis. Just-in-time approach still yields a significant performance boost.

OOPSCONCEPT IN JAVA
An object-oriented program can be characterized as data controlling access to code.

Abstraction:

Hidden information about the objects. objects as concrete entities that respond to messages telling them to do something. This is the essence of object-oriented programming.

Encapsulation:

Encapsulation is the mechanism that binds together code and the data it manipulates, and keeps both safe from outside interference and misuse.

Inheritance :

Inheritance is the process by which one object acquires the properties of another object. This is important because it supports the concept of hierarchical classification.

Polymorphism:

Polymorphism (from the Greek, meaning “many forms”) is a feature that allows one interface to be used for a general class of actions.

CLASS:

A class describes all the attributes of objects, as well as the methods that implement the behavior of member objects. It’s a comprehensive data type which represents a blue print of objects. A template that describes the kinds of state and behavior that objects of its type support.

OBJECT:

An object is an entity that has attributes, behavior, and identity. Objects are members of a class. Attributes and behavior of an object are defined
by the class definition At runtime, when the Java Virtual Machine (JVM) encounters the new keyword, it will use the appropriate class to make an object which is an instance of that class.

SAMPLE PROGRAM
class Example {
// Your program begins with a call to main ().
public static void main(String args[]) {

// main( ) must be declared as public, since it must be called by code outside of

//its class when the program is started Static -instantiate a particular instance of the class
//args receives any command-line argumentspresent when the program is executed.

System.out.println("This is a simple Java program.");

//System is a predefined class that provides access to the system, and out is the output stream that is connected to the console. println ( ) displays the string which is passed to it

}

}

Source File Name: Example.java
Compile: javac Example.java
Run: java Example

APPLET:

            

            An applet is an application designed to be transmitted over the Internet and executed by a Java-compatible Web browser. An applet is actually a tiny Java program, dynamically downloaded across the network, just like an image, sound file, or video clip.

 

 MULTI THREADING:

                       Multi threading is process of program’s are executed simultaneously without effecting any system crashes. The Java run-time system comes with an elegant yet sophisticated solution for multiprocess synchronization that enables you to construct smoothly running interactive systems. 

KEY WORDS

  abstract                   continue             goto                      package         synchronized

  assert                      default               if                           private            this

  boolean                  do                     implements             protected        throw

  break                     double               import                    public              throws

  byte                       else                   instanceof               return              transient

  case                      extends               int                          short               try

  catch                     final                   interface                 static               void

  char                     finally                 long                        strictfp             volatile

  class                    float                   native                      super              while

  const                    new                   switch

DATA TYPE:

   

      

short	8	float	32	char	8
byte	16	double	64
int	32
long	64

DECLARE THE VARIABLE / ARRAY DECLARATION IN JAVA

Variable is identifier its holds a value

int a; a has integer type

 Assigned a value to variable

 a=10;

Type Casting:

var=(type)var

 ARRAY:

int a[]=new in[12]

char[][] name=new char[][]

OPERATORS

ARTHIMTIC	RELATION	LOGICAL	BITWISE
Addition[+]	< ,>	AND(&&)	AND(&)
Subtraction[-]	<=,=>	OR (||)	OR(|)
Multiplication[*]	==	NOT (!)	XOR(^)
Division [\]	!=	XOR( ^)	SHIFT LIFT(<<)
Modulus[%]			SHIFT RIGHT(>>)
			SHIFT RIGHT FILL ZERO(>>>)