Java is a general-purpose computer programming language that is concurrent, class-based, object-oriented. Java inherits its object-oriented features from C++. Java language was created by James Gosling, a software developer at Sun Microsystems, in 1991.
It was first named as “OAK” but it was later named as “JAVA”. It was officially launched in 1995, Java derives much of its components and characteristics from C and C++.
It was developed in an attempt to create a portable platform-independent language. Java source code files (files with a .java extension) are compiled into a format called bytecode (files with a .class-extension), which can then be executed by a Java interpreter.
Mostly java uses three extensions .java, .class and .jar. Compiled Java code can run on most computers because Java interpreters and run-time environments, known as Java Virtual Machines (JVMs), exist for most operating systems, including UNIX, the Macintosh OS, and Windows.
Byte-code can also be converted directly into machine language instructions by a just-in-time compiler (JIT). The advantage of Java is it is platform-independent because of the byte-code, the program generates the bytecode and it can be executed on multiple operating systems.
Another advantage of Java is it consumes less memory, for comparison with other programming languages.
Java Example,
class Abc{
public static void main(String args[]){
System.out.println(“Hello World!”);
}
} Java is the foundation for virtually every type of networked application and is the global standard for developing and delivering embedded and mobile applications, games, Web-based content, and enterprise software.
With more than 9 million developers worldwide, Java enables you to efficiently develop, deploy and use exciting applications and services. From laptops to data centers, game consoles to scientific supercomputers, cell phones to the Internet, Java is everywhere!
- 97% of Enterprise Desktops Run Java
- 89% of Desktops (or Computers) in the U.S. Run Java
- 9 Million Java Developers Worldwide
- #1 Choice for Developers
- #1 Development Platform
- 3 Billion Mobile Phones Run Java
- 100% of Blu-ray Disc Players Ship with Java
- 5 Billion Java Cards in Use
- 125 million TV devices run Java
- 5 of the Top 5 Original Equipment Manufacturers Ship Java ME
Features of Java
Platform Independent
Unlike many other programming languages including C and C++, when Java is compiled, it is not compiled into platform specific machine, rather into platform independent byte code. This byte code is distributed over the web and interpreted by virtual Machine (JVM) on whichever platform it is being run.
Architectural-Neutral
Java compiler generates an architecture-neutral object file format which makes the compiled code be executable on many processors, with the presence of Java runtime system. Portable Being architectural-neutral and having no implementation dependent aspects of the specification makes Java portable. The compiler in Java is written in ANSI C with a clean portability boundary which is a POSIX subset.
Multithreaded
With Java’s multithreaded feature it is possible to write programs that can do many tasks simultaneously. This design feature allows developers to construct smoothly running interactive applications.
Interpreted
Java byte code is translated on the fly to native machine instructions and is not stored anywhere. The development process is more rapid and analytically since the linking is an incremental and light weight process.
Dynamic
Java is considered to be more dynamic than C or C++ since it is designed to adapt to an evolving environment. Java programs can carry an extensive amount of run-time information that can be used to verify and resolve accesses to objects at run-time.
Robust
Java makes an effort to eliminate error-prone situations by emphasizing mainly on compile time error checking and runtime checking.
Object Oriented
In Java, everything is an Object. Java can be easily extended since it is based on the Object model.
Simple
Java is designed to be easy to learn. If you understand the basic concept of OOP Java would be easy to master.
Secure
With Java’s secure feature it enables to develop virus-free, tamper-free systems. Authentication techniques are based on public-key encryption.
High Performance
With the use of Just-In-Time compilers, Java enables high performance.
Distributed
Java is designed for the distributed environment of the internet.
Versions of Java
Major release versions of Java, along with their release dates:
- JDK 1.0 (January 21, 1996)
- JDK 1.1 (February 19, 1997)
- J2SE 1.2 (December 8, 1998)
- J2SE 1.3 (May 8, 2000)
- J2SE 1.4 (February 6, 2002)
- J2SE 5.0 (September 30, 2004)
- Java SE 6 (December 11, 2006)
- Java SE 7 (July 28, 2011)
- Java SE 8 (March 18, 2014 )
