Java is a programming language and a platform. It is a high level, robust, object-oriented and secure programming language.

What do I mean by Platform?

Any hardware or software environment in which a program runs, is known as a platform. Since Java has a runtime environment (JRE) and API, it is called a platform.

Let's have a quick look at Java programming example.

class Simple{  

    public static void main(String args[]){  

     System.out.println("Hello Java");  

    }  

}

Applications of Java

According to Sun, 3 billion devices run Java. There are many devices where Java is currently used. Some of them are as follows:

• Desktop Applications:

All desktop applications can easily be developed in Java. Java also provides GUI development capability through various means mainly Abstract Windowing Toolkit (AWT), Swing and JavaFX.

• Web Based Applications: Java is used to develop web applications. It provides a vast support for web applications through Servlets, Struts or JSPs. With the help of these technologies, you can develop any kind of web application that you require. such as irctc.co.in, javatpoint.com, etc.

• Enterprise Applications:

An enterprise application is a large software system which operates in a corporate environment, to satisfy the needs of an organization, rather than of individual users. Java is the first choice for the development of enterprise applications because of its robust features that match the requirements for the same. such as banking applications.

• Embedded System: An embedded system, also known as an integrated system, is a combination of many small computing units that assemble together to perform dedicated functions for the larger systems.
• Smart Card
• Robotics
• Mobile Applications
• Games, etc.

Types of Java Applications

There are mainly 4 types of applications that can be created using Java programming:

1) Standalone Application

Standalone applications are also known as desktop applications or window-based applications. These are traditional software that we need to install on every machine. Examples of standalone application are Media player, antivirus, etc. AWT and Swing are used in Java for creating standalone applications.

2) Web Application

An application that runs on the server side and creates a dynamic page is called a web application. Currently, Servlet, JSP, Struts, Spring, Hibernate, JSF, etc. technologies are used for creating web applications in Java.

3) Enterprise Application

An application that is distributed in nature, such as banking applications, etc. is called enterprise application. It has advantages of the high-level security, load balancing, and clustering. In Java, EJB is used for creating enterprise applications.

4) Mobile Application

An application which is created for mobile devices is called a mobile application. Currently, Android and Java ME are used for creating mobile applications.

Java Platforms / Editions

There are 4 platforms or editions of Java:

1) Java SE (Java Standard Edition)

It is a Java programming platform. It includes Java programming APIs such as java.lang, java.io, java.net, java.util, java.sql, java.math etc. It includes core topics like OOPs, String, Regex, Exception, Inner classes, Multithreading, I/O Stream, Networking, AWT, Swing, Reflection, Collection, etc.

2) Java EE (Java Enterprise Edition)

It is an enterprise platform which is mainly used to develop web and enterprise applications. It is built on the top of the Java SE platform. It includes topics like Servlet, JSP, Web Services, EJB, JPA, etc.

3) Java ME (Java Micro Edition)

It is a micro platform which is mainly used to develop mobile applications.

4) JavaFX

It is used to develop rich internet applications. It uses a light-weight user interface API.

Why Do I Need Java?

Java works on different platforms (Windows, Mac, Linux, Raspberry Pi, etc.)

i. It is one of the most popular programming language in the world.

ii. It is easy to learn and simple to use.

iii. It is open-source and free.

iv. It is secure, fast and powerful.

v. It has a huge community support (tens of millions of developers).

vi. Java is an object oriented language which gives a clear structure to programs and allows code to be reused, lowering development costs.

vii. As Java is close to C++ and C#, it makes it easy for programmers to switch to Java or vice versa.

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.

A list of most important features of Java language is given below.

Java Features

• Simple
• Object-Oriented
• Portable
• Platform independent
• Secured
• Robust
• Architecture neutral
• Interpreted
• High Performance
• Multithreaded
• Distributed
• Dynamic

Simple:

Java is very easy to learn, and its syntax is simple, clean and easy to understand. According to Sun, Java language is a simple programming language because:

Java syntax is based on C++ (so easier for programmers to learn it after C++). Java has removed many complicated and rarely-used features, for example, explicit pointers, operator overloading, etc. There is no need to remove unreferenced objects because there is an Automatic Garbage Collection in Java.

Object-oriented:

Java is an object-oriented programming language. Everything in Java is an object. Object-oriented means we organize our software as a combination of different types of objects that incorporates both data and behavior.

Object-oriented programming (OOPs) is a methodology that simplifies software development and maintenance by providing some rules.

Basic concepts of OOPs are:

i. Object ii. Class iii. Inheritance iv. Polymorphism v. Abstraction vi. Encapsulation

Platform Independent:

Java is platform independent

Java is platform independent because it is different from other languages like C, C++, etc. which are compiled into platform specific machines while Java is a write once, run anywhere language. A platform is the hardware or software environment in which a program runs.

There are two types of platforms software-based and hardware-based. Java provides a software-based platform.

The Java platform differs from most other platforms in the sense that it is a software-based platform that runs on the top of other hardware-based platforms. It has two components:

• Runtime Environment
• API(Application Programming Interface)

Java code can be run on multiple platforms, for example, Windows, Linux, Sun Solaris, Mac/OS, etc. Java code is compiled by the compiler and converted into bytecode. This bytecode is a platform-independent code because it can be run on multiple platforms, i.e., Write Once and Run Anywhere(WORA).

Secured:

Java is best known for its security. With Java, we can develop virus-free systems. Java is secured because:

• No explicit pointer.
• Java Programs run inside a virtual machine sandbox how Java is secured.

• Classloader:

Classloader in Java is a part of the Java Runtime Environment(JRE) which is used to load Java classes into the Java Virtual Machine dynamically. It adds security by separating the package for the classes of the local file system from those that are imported from network sources.

• Bytecode Verifier: It checks the code fragments for illegal code that can violate access right to objects.

• Security Manager: It determines what resources a class can access such as reading and writing to the local disk.

Java language provides these securities by default. Some security can also be provided by an application developer explicitly through SSL, JAAS, Cryptography, etc.

Robust:

Robust simply means strong. Java is robust because:

• It uses strong memory management.
• There is a lack of pointers that avoids security problems.
• There is automatic garbage collection in java which runs on the Java Virtual Machine to get rid of objects which are not being used by a Java application anymore.
• There are exception handling and the type checking mechanism in Java. All these points make Java robust.

Architecture-neutral:

Java is architecture neutral because there are no implementation dependent features, for example, the size of primitive types is fixed.

In C programming, int data type occupies 2 bytes of memory for 32-bit architecture and 4 bytes of memory for 64-bit architecture. However, it occupies 4 bytes of memory for both 32 and 64-bit architectures in Java.

Portable:

Java is portable because it facilitates you to carry the Java bytecode to any platform. It doesn't require any implementation.

High-performance:

Java is faster than other traditional interpreted programming languages because Java bytecode is "close" to native code. It is still a little bit slower than a compiled language (e.g., C++). Java is an interpreted language that is why it is slower than compiled languages, e.g., C, C++, etc.

Distributed:

Java is distributed because it facilitates users to create distributed applications in Java. RMI and EJB are used for creating distributed applications. This feature of Java makes us able to access files by calling the methods from any machine on the internet.

Multi-threaded:

A thread is like a separate program, executing concurrently. We can write Java programs that deal with many tasks at once by defining multiple threads. The main advantage of multi-threading is that it doesn't occupy memory for each thread. It shares a common memory area. Threads are important for multi-media, Web applications, etc.

Dynamic:

Java is a dynamic language. It supports dynamic loading of classes. It means classes are loaded on demand. It also supports functions from its native languages, i.e., C and C++.

Java supports dynamic compilation and automatic memory management (garbage collection).

It is not necessary to have any prior programming experience before you learn Java.

Happy Learning.