There is given many features of java. They are also called java buzzwords.
1.Simple
2.Object-oriented
3.Platform independent
4.Secured
5.Robust
6.Architecture neutral
7.Portable
8.Dynamic
9.Interpreted
10.High Performance
11.Multithreaded
12.Distributed
Simple
Java is simple in the sense that:
syntax is based on C++ (so easier for programmers to learn it after C++).
removed many confusing and/or rarely-used features e.g., explicit pointers, operator overloading etc.
No need to remove unreferenced objects because there is Automatic Garbage Collection in java.
Object-oriented
Object-oriented means we organize our software as a combination of different types of objects that incorporates both data and behaviour.
Object-oriented programming(OOPs) is a methodology that simplify software development and maintenace by providing some rulues.
Basic concepts of OOPs are:
(1) Object
(2) Class
(3) Inheritance
(4) Polymorphism
(5) Abstraction
(6) Encapsulation
Platform Independent
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 software-based platform. The Java platform differs from most other platforms in the sense that it's a software-based platform that runs on top of other hardware-based platforms.It has two components:
Runtime Environment
API(Application Programming Interface)
Java code can be run on multiple platforms e.g.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 secured because:
No explicit pointer
Programs run inside virtual machine sandbox.
Classloader- adds security by separating the package for the classes of the local file system from those that are imported from network sources.
Bytecode Verifier- checks the code fragments for illegal code that can violate accesss right to objects.
Security Manager- determines what resources a class can access such as reading and writing to the local disk.
These security are provided by java language. Some sucurity can also be provided by application developer through SSL,JAAS,cryptography etc.
Robust
Robust simply means strong. Java uses strong memory management. There are lack of pointers that avoids security problem. There is automatic garbage collection in java. There is exception handling and type checking mechanism in java. All these points makes java robust.
Architecture-neutral
There is no implementation dependent features e.g. size of primitive types is set.
Portable
We may carry the java bytecode to any platform.
High-performance
Java is faster than traditional interpretation since byte code is "close" to native code still somewhat slower than a compiled language (e.g., C++)
Distributed
We can create distributed applications in java. RMI and EJB are used for creating distributed applications. We may 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 shares the same memory. Threads are important for multi-media, Web applications etc.
Java technology is wide used currently. Let's start learning of java from basic questions like what is java, where it is used, what type of applications are created in java and why use java?
What is Java?
Java is an object oriented, internet programming language.
Its main features are:-
ØPlatform Independence.
ØSecurity.
Where it is used?
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 such as acrobat reader, media player, antivirus etc.
Web Applications such as irctc.co.in
Enterprise Applications such as banking applications.
Mobile
Embedded System
Smart Card
Robotics
Games etc.
Types of Java Applications
There are mainly 4 type of applications that can be created using java:
1) Standalone Application
It is also known as desktop application or window-based application. An application that we need to install on every machine such as 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 dynamic page, is called web application. Currently, servlet, jsp, struts, 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. It has the advantage of high level security, load balancing and clustering. In java, EJB is used for creating enterprise applications.
4) Mobile Application
An application that is created for mobile devices. Currently Android and Java ME are used for creating mobile applications.
Java code can be run on multiple platforms e.g.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).
