Showing posts with label Java. Show all posts
Showing posts with label Java. Show all posts

Friday, 26 November 2021

Java Oops Concept

Java Oops Concept:

1.       Objects

2.       Class

3.       Inheritance

4.       Polymorphism

5.       Abstraction

6.       Encapsulation

Object :

Any entity that has state and behaviour is known as an Object.

An object can be defined as an instance of a class.

Example :

Object = {property 1: value1, property 2: value 2……property n: value n}

Class :

  • Collection of object is called class.
  • It is a logical entity
  • Class doesn’t consume any space.
  • A class can also be defined as a blueprint from which you can create an individual object.

 

 

Inheritance :

When one object acquires all the properties and behaviours of a parent object, it is known as inheritance.

It provides code reusability.

It is a used to achieve runtime polymorphism.

 

Polymorphism :

If one task is performed in different way, it is known as polymorphism.

In java we use method overloading and method overriding.

 

Abstraction :

Hinding internal details and showing functionality is known as abstraction.

 

Encapsulation :

Binding or wrapping code and data together into a single unit are known as encapsulation.

Naming Convention :

1.     Class

    . It should start with the uppercase letter.

  It should be a noun such as Color, Button, System, Thread, etc.
Use appropriate words, instead of acronyms.

Example :

Public class Employee {

//code snippet

}

 

2.     Interface

It should start with the uppercase letter.

It should be an adjective such as Runnable, Remote, ActionListener.

Use appropriate words, instead of acronyms.

 

Example :

 

Interface Printable

{

//code snippet

}

3.     Method

It should start with lowercase letter.
It should be a verb such as main(), print(), println().
If the name contains multiple words, start it with a lowercase letter followed by an uppercase letter such as actionPerformed().

Example :

Class Employee

{

//method

Void get( )

{

//code snippet

}

}

4.     Variables

It should start with a lowercase letter such as id, name.

It should not start with the special characters like & (ampersand), $ (dollar), _ (underscore).

If the name contains multiple words, start it with the lowercase letter followed by an uppercase letter such as firstName, lastName.

Avoid using one-character variables such as x, y, z.

Example :

Class Employee

{

// variables

Int id;

Char name;

}

5.     Package

It should be a lowercase letter such as java, lang.
If the name contains multiple words, it should be separated by dots (.) such as java.util, java.lang.

Example :

Package com.abc.xyz;

Class employee

{

//code

}

 

6.     Constant

It should be in uppercase letters such as RED, YELLOW.

If the name contains multiple words, it should be separated by an underscore(_) such as MAX_PRIORITY.

It may contain digits but not as the first letter.

Example :

Class Employee

{

//constant

Static final int MIN_Age = 18;

//code

}

Object and class Example:

Public class Student {

Int id ;

String name;

Public static void main (String[] args)

{

Student s1 = new Student();

System.out.println(s1.id);

System.out.println(s1.name);

}

}

Syntax of class :

Class <class_name>{

Field;

Method;

}

 

Class Student {

Int rollno;

String name;

Void insertRecord(int r, String n)

{

Rollno = r;

Name = n;

}

Void display()

{

System.out.println(rollno+ “ “ +name);

}

Class StudentTest {

Public static void main (String[] args)

{

Student s1 = new student();

Student s2 = new Student();

S1.insertRecord(101, “Ram”);

S2.insertRecord(102, “Sita”);

S1.display();

S2.display();

}

}

 

Class Student {

Int id;

String name;

}

Class StudentTest {

Public static void main (String arg[])

{

Student s1 = new Student();

Student s2 = new student();

S1.id = 101;

S1.name = “Ram”;

S2.id = 102;

S2.name = “Sita”;

System.out.println(s1.id+ “ “ s1.name);

System.out.println(s2.id+ “ “ s2.name);

}

}

Sunday, 21 November 2021

Introduction to java | Java tutorials | History of Java | JDK | JVM | JRE | Different Types of Java Platforms

What is Java?

Java is a class-based object-oriented programming language.

It is the most popular programming language.

Building web and desktop applications.

The language of choice for Android programming.

 

Java Platform

Java Platform is a collection of programs that help programmers to develop and run Java programming applications efficiently.

It includes an execution engine, a compiler, and a set of libraries in it.

It is a set of computer software and specifications.

James Gosling developed the Java platform at Sun Microsystems, and the Oracle Corporation later acquired it.

Java is a multi-platform, object-oriented, and network-centric language. It is among the most used programming language. Java is also used as a computing platform.

What is Java used for?

It is used for developing Android Apps

Helps you to create Enterprise Software

Wide range of Mobile java Applications

Use for big data Analytics.

Java Programming of Hardware devices

Used for Server-Side Technologies like Apache, JBoss, GlassFish, etc.

 

History of Java Programming Language

The Java language was initially called OAK.

it was developed for handling portable devices and set-top boxes.

In 1995, Sun changed the name to “Java” and modified the language to take advantage of the burgeoning www (World Wide Web) development business.

Later, in 2009, Oracle Corporation acquired Sun Microsystems and took ownership of three key Sun software assets: Java, MySQL, and Solaris.

Java Versions

JDK Alpha and Beta

   1995

JDK 1.0

23rd Jan 1996

JAVA SE 15

           15th Sep 2020 (latest Java Version)

 

 

Java Features

  • It is one of the easy-to-use programming languages to learn.
  • Write code once and run it on almost any computing platform.
  • Java is platform-independent. Some programs developed in one machine can be executed in another machine.
  • It is designed for building object-oriented applications.
  • It is a multi threaded language with automatic memory management.
  • It is created for the distributed environment of the Internet.
  • Facilitates distributed computing as its network-centric.

Java Development kit (JDK)

 

JDK is a software development environment used for making applets and Java applications.

Java developers can use it on Windows, macOS, Solaris, and Linux.

It is possible to install more than one JDK version on the same computer.

Why use JDK?

 

· JDK contains tools required to write Java programs and JRE to execute them.

· It includes a compiler, Java application launcher, Applet viewer, etc.

· Compiler converts code written in Java into byte code.

Java Virtual Machine (JVM):

 

Java Virtual Machine (JVM) is an engine that provides a runtime environment to drive the Java Code or applications.

It converts Java bytecode into machine language.

Why use JVM?

  • JVM provides a platform-independent way of executing Java source code.
  • It has numerous libraries, tools, and frameworks.
  • Once you run a Java program, you can run on any platform and save lots of time.
  • JVM comes with JIT (Just-in-Time) compiler that converts Java source code into low-level machine language. Hence, it runs faster than a regular application.

Java Runtime Environment (JRE)

JRE is a piece of software that is designed to run other software.

It contains the class libraries, loader class, and JVM.

If you are not a programmer, you don’t need to install JDK, but just JRE to run Java programs.

Why use JRE (Java Runtime Environment)

  • JRE contains class libraries, JVM, and other supporting files. It does not include any tool for Java development like a debugger, compiler, etc.
  • It uses important package classes like math, swing, util, lang, awt, and runtime libraries.
  • If you have to run Java applets, then JRE must be installed in your system.

 

Different Types of Java Platforms

1.       Java Platform, Standard Edition (Java SE):

Java SE’s API offers the Java programming language’s core functionality.

It defines all the basis of type and object to high-level classes.

It is used for networking, security, database access, graphical user interface (GUI) development, and XML parsing.

 

2.       Java Platform, Enterprise Edition (Java EE):

The Java EE platform offers an API and runtime environment for developing and running highly scalable, large-scale, multi-tiered, reliable, and secure network applications.

 

3.       Java Programming Language Platform, Micro Edition (Java ME):

The Java ME platform offers an API and a small-footprint virtual machine running Java programming language applications on small devices, like mobile phones.

 

API :  Application programming interface

An API is a set of programming code that enables data transmission between one software product and another. It also contains the terms of this data exchange.

 

4.       Java FX: 

JavaFX is a platform for developing rich internet applications using a lightweight user-interface API. It user hardware-accelerated graphics and media engines that help Java take advantage of higher-performance clients and a modern look-and-feel and high-level APIs for connecting to networked data sources.

First Program :

 

Class abc {

Public static void main(String args[]){

System.out.println(“Hello World”);

}

}

 


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