Core java

PRESESNTATION
CORE JAVA
Prepared By :Ganesh N.Chittalwar

CONTENTS
 Introduction to core java
 Java features
 Why java is called as platform
 Difference between class and object
 What is class?
 Object.
 Java basic primitive types
 Arrays in java.
 Object oriented programming
 What is the Standard Packages
 Example of Package and library creation
 What make a library package

INTRODUCTION OF JAVA
 Java programming language
 The one we use to write our program
 Compiled to byte code of JVM
 Java virtual machine (JVM)
 Java interpreter – interpret the compiled byte code
 Software simulated CPU architecture
 Cross-platform: support Linux, Windows,
PalmOS…etc.
 Java runtime environment (JRE)
 Predefined set of java classes available to use
 Core Java APIs – basic utilities, I/O, graphics,
network…

FEATURES OF JAVA
The primary objective of Java programming language creation was to
make it portable, simple and secure programming language. Apart from
this, there are also some excellent features which play an important role in
the popularity of this language. The features of Java are also known as
java buzzwords.

WHY JAVA IS CALLED AS “PLATFORM”
A platform is basically the hardware or
software environment in which a program
runs. Java provides software-based platform
i.e. JVM, which can run applications
developed using the Java Programming
Language.

DIFFERENCE BETWEEN CLASS AND OBJECT
class is just a blueprint. A class defines the available characteristics and
behavior of a set of similar objects.
e.g. Car class defined has so many attributes and behaviour such as
start(),stop(),accelerate() etc,
Example:
Public class dog{ <<< dog this is class
String breed;
Int age;
String color;
void barking(){
}
Void hungry(){
}
void sleeping(){
}
}

WHAT IS CLASS?
 Class introduces a new data type
 A class describes a set of objects that have
identical characteristics (data elements) and
behaviors (methods).
 Existing classes provided by JRE
 User defined classes
 Once a class is established, you can make
as many objects of it as you like, or none.

SIMPLE EXAMPLE :CLASS PERSON
 A Person has some attributes
 The class defines these properties for all
people
 Each person gets his own copy of the fields
 Attributes = properties = fields

OBJECT:
object or instance is basic runtime entity. E.g. Maruti Alto, WaganR, Maruti
Swift etc.
Example :
public class Puppy{
Public puppy(string name){
Sop(passed name is:”+name);
}
Public static void main(string[]args){
//this object
Puppy mypuppy =new puppy(“tommy”);
}
}

JAVA BASICS: PRIMITIVE TYPES
 One group of types get special treatment in
Java
 Variable is not created by “new”, not a
reference
 Variable holds the value directlyy77

ARRAY INDEX
 int[] age = new int[5];
The first element of array is age[], second is age[1] and so on.
If the length of an array is n, the last element will be arrayName[n-1]. Since the
length of arr array is 5, the last element of the array is age[4]
The default initial value of elements of an array is 0 for numeric types
and false for boolean.

ARRAY IN LENGTH
 Arrayname.length
 Int s =arr.length;
 if we make for 5 element
 if we need this statement and arraylength
  in the above length show if we create array
that time we don’t know size ..
 And from user any number enter he is don’t
know number any number entered there no fix.
he is don’t know his size …for this know size
that time using arraylength also use for.. loop.

OBJECT ORIENTED PROGRAMMING
Object-oriented programming (OOP) is a
programming based on the concept of
"objects",
which are data structures that contain data, in
the form of fields, often known as attributes
and code in the form of procedures, often
known as methods.

JAVA OBJECT ORIENTED
 Inheritance
 Abstraction
 Encapsulation
 Polymorphism
 Interface
 packages

INHERITANCE
inheritance is a way implement IS-A relationship.
Subclass inherits the super class properties like ..data
member, method.inheritance is the way of resusebility of
code
.
Example :
class student {
…..
Public class collagerstudent extends student{
…
Show method(){
}
}

ABTRACTION
Abstraction is a process of hiding the implementation
details from the user. Оnly the functionality will be provided
to the user. In Java,abstraction is achieved
using abstract classes and interfaces. ...

EXAMPLE OF ABSTRACTION
Example :
// concept of Abstraction
abstract class Shape
{
String color;
// these are abstract methods
abstract double area();
public abstract String to String();
// abstract class can have constructor
public Shape(String color) {
System.out.println("Shape constructor called");
this.color = color;
}
// this is a concrete method
public String getColor() {
return color;
}
}

ENCAPSULATION
Encapsulation in Java is a mechanism of
wrapping the data (variables) and code acting
on the data (methods) together as a single
unit.
Declare the variables of a class as private.
Provide public setter and getter methods to
modify and view the variables values.

POLYMORPHISM
Polymorphism is the ability of an object to
take on many forms. The most common use
of polymorphism in OOP occurs when a
parent class reference is used to refer to a
child class object. Any Java object that can
pass more than one IS-A test is considered to
be polymorphic.

HOW JAVA IS PLATFORM INDEPENDENT
 Java program, once compiled , can be run
on any platform without recompiling.
 On compilation Java program is compiled
into bytecode. This bytecode is platform
independent and can be run on any
machine. Any machine with Java Runtime
Environment can run Java Programs.

WHAT IS PACKAGE IN JAVA?
A Package is a collection of related classes. It helps organize your classes into a folder
structure and make it easy to locate and use them,
Although interfaces and classes with the same name cannot appear in the same package,
they can appear in different packages. This is possible by assigning a separate namespace
to each package.
example
Package c1;
Class c1(){
Pulblic void m1(){
System.out.println(“m1 of c1”);
}
Public static void main (String args[]);
C1 obj = new c1();
Obj.m1();
}
}

WHAT IS THE STANDARD PACKAGES
package
package is a collection of related classes and interfaces.
package is mainly used avoid naming conflicts.
package concept is similar to "namespace"
java has so many in-built packages . e.g.
java.awt
java.io
java.util
java.lang
and so on

There are many packages including the sub packages. But we can assume them in a specific
category then click the link to watch the image. java.lang, java.util, java.awt and sub categories
are shown below.

EXAMPLE OF PACKAGE AND LIBRARY
CREATION
Libraries are a great way to create modular code that can be easily shared.
In the Dart ecosystem, libraries are created and distributed as packages.
Dart has two kinds of packages: application packages, which may include
local libraries, and library packages.

WHAT MAKES A LIBRARY PACKAGE
The following diagram shows the layout of the
simplest library package:

THE MINIMAL REQUIREMENTS FOR A LIBRARY ARE:
pubspec file
The pubspec.yml file for a library is the same as for an
application package—there is no special designation to
indicate that the package is a library.
lib directory
As you might expect, the library code lives under
the lib directory and is public to other packages. You can
create any hierarchy under lib, as needed. By convention,
implementation code is placed under lib/src.

Core java

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