In some procedural language, you could even obtain the memory location of a data structure. Armed with this location, you could read and write to the data at a later time, or accidentally overwrite the contents.

Java is an object-oriented language. An object-oriented language deals with objects. Objects contain both data (member variables) and code (methods). Each object belongs to a particular class, which is a blueprint describing the member variables and methods an object offers. In Java, almost every variable is an object of some type or another – even strings. Object-oriented programming requires a different way of thinking, but is a better way to design software than procedural programming.

There are many popular object-oriented languages available today. Some like Smalltalk and Java are designed from the beginning to be object-oriented. Others, like C++, are partially object-oriented, and partially procedural. In C++, you can still overwrite the contents of data structures and objects, causing the application to crash. Thankfully, Java prohibits direct access to memory contents, leading to a more robust system.
Portable

Most programming languages are designed for a specific operating system and processor architecture. When source code (the instructions that make up a program) are compiled, it is converted to machine code which can be executed only on one type of machine. This process produces native code, which is extremely fast.

Another type of language is one that is interpreted. Interpreted code is read by a software application (the interpreter), which performs the specified actions. Interpreted code often doesn’t need to be compiled – it is translated as it is run. For this reason, interpreted code is quite slow, but often portable across different operating systems and processor architectures.

Java takes the best of both techniques. Java code is compiled into a platform-neutral machine code, which is called Java bytecode. A special type of interpreter, known as a Java Virtual Machine (JVM), reads the bytecode, and processes it. Figure One shows a disassembly of a small Java application. The bytecode, indicated by the arrow, is represented in text form here, but when compiled it is represented as bytes to conserve space. Learn more about these techniques with free white papers at IT Knowledge Hub.

Figure One – Bytecode disassembly for “HelloWorld”

The approach Java takes offers some big advantages over other interpreted languages. Firstly, the source code is protected from view and modification – only the bytecode needs to be made available to users. Secondly, security mechanisms can scan bytecode for signs of modification or harmful code, complimenting the other security mechanisms of Java. Most of all though, it means that Java code can be compiled once, and run on any machine and operating system combination that supports a Java Virtual Machine (JVM). Java can run on Unix, Windows, Macintosh, and even the Palm Pilot. Java can even run inside a web browser, or a web server. Being portable means that the application only has to be written once – and can then execute on a wider range of machines. This saves a lot of time, and money.
Multi-threaded

If you’ve ever written complex applications in C, or PERL, you’ll probably have come across the concept of multiple processes before. An application can split itself into separate copies, which run concurrently. Each copy replicates code and data, resulting in increased memory consumption. Getting the copies to talk together can be complex, and frustrating. Creating each process involves a call to the operating system, which consumes extra CPU time as well.

A better model is to use multiple threads of execution, referred to as threads for short. Threads can share data and code, making it easier to share data between thread instances. They also use less memory and CPU overhead. Some languages, like C++, have support for threads, but they are complex to use. Java has support for multiple threads of execution built right into the language. Threads require a different way of thinking, but can be understood very quickly. Thread support in Java is very simple to use, and the use of threads in applications and applets is quite commonplace.
Automatic garbage collection

No, we’re not talking about taking out the trash (though a computer that could literally do that would be kind of neat). The term garbage collection refers to the reclamation of unused memory space. When applications create objects, the JVM allocates memory space for their storage. When the object is no longer needed (no reference to the object exists), the memory space can be reclaimed for later use.

Languages like C++ force programmers to allocate and deallocate memory for data and objects manually. This adds extra complexity, but also causes another problem – memory leaks. When programmers forget to deallocate memory, the amount of free memory available is decreased. Programs that frequently create and destroy objects may eventually find that there is no memory left. In Java, the programmer is free from such worries, as the JVM will perform automatic garbage collection of objects.
Secure

Security is a big issue with Java. Since Java applets are downloaded remotely, and executed in a browser, security is of great concern. We wouldn’t want applets reading our personal documents, deleting files, or causing mischief. At the API level, there are strong security restrictions on file and network access for applets, as well as support for digital signatures to verify the integrity of downloaded code. At the bytecode level, checks are made for obvious hacks, such as stack manipulation or invalid bytecode. The strong security mechanisms in Java help to protect against inadvertent or intentional security violations, but it is important to remember that no system is perfect. The weakest link in the chain is the Java Virtual Machine on which it is run – a JVM with known security weaknesses can be prone to attack. It is also worth noting that while there have been a few identified weaknesses in JVMs, they are rare, and usually fixed quickly.
Network and “Internet” aware

Java was designed to be “Internet” aware, and to support network programming. The Java API provides extensive network support, from sockets and IP addresses, to URLs and HTTP. It’s extremely easy to write network applications in Java, and the code is completely portable between platforms. In languages like C/C++, the networking code must be re-written for different operating systems, and is usually more complex. The networking support of Java saves a lot of time, and effort.

Java also includes support for more exotic network programming, such as remote-method invocation (RMI), CORBA and Jini. These distributed systems technologies make Java an attractive choice for large distributed systems.
Simplicity and ease-of-use

Java draws its roots from the C++ language. C++ is widely used, and very popular. Yet it is regarded as a complex language, with features like multiple-inheritance, templates and pointers that are counter-productive. Java, on the other hand, is closer to a “pure” object-oriented language. Access to memory pointers is removed, and object-references are used instead. Support for multiple-inheritance has been removed, which lends itself to clearer and simpler class designs. The I/O and network library is very easy to use, and the Java API provides developers with lots of time-saving code (such as networking and data-structures). After using Java for awhile, most developers are reluctant to return to other languages, because of the simplicity and elegance of Java.

This article is free for republishing
Source: http://www.articlealley.com/article_915553_11.html

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Black Shark

Exciting games involving the air battle by Russian soldiers.

Many of these features for aircraft with weapons ready to fight in the air.

The gameplay is where there are many missions in his adventures.

Support game LCD resolution with 240×320 pixels.

Follow the adventures of air combat, and install this cool game in your handphone.

Get here soon : Black Shark

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Why do people need JAVA?

There are lots of applications and websites that won’t work unless you have Java installed, and more are created every day. Java is fast, secure, and reliable. From laptops to datacenters, game consoles to scientific supercomputers, cell phones to the Internet, Java is everywhere!

Characteristics of JAVA

The programs you create are portable in a network
The code is robust, here meaning that, unlike programs written in C++ and perhaps some other languages, the Java objects can contain no references to data external to themselves or other known objects.
Java is object-oriented, which means that, among other characteristics, an object can take advantage of being part of a class of objects and inherit code that is common to the class.
In addition to being executed at the client rather than the server, a Java applet has other characteristics designed to make it run fast.
Relative to C++, Java is easier to learn. (However, it is not a language you’ll pick up in an evening)

Difference between JAVA and JAVASCRIPT

JavaScript should not be confused with Java. JavaScript, which originated at Netscape, is interpreted at a higher level and is easier to learn than Java, but lacks some of the portability of Java and the speed of bytecode. Because Java applets will run on almost any operating system without requiring recompilation and because Java has no operating system-unique extensions or variations, Java is generally regarded as the most strategic language in which to develop applications for the Web. (However, JavaScript can be useful for very small applications that run on the Web client or server.)

Editions

Sun has defined and supports four editions of Java targeting different application environments and segmented many of its APIs so that they belong to one of the platforms. The platforms are:

Java Card for smartcards.
Java Platform, Micro Edition (Java ME) — targeting environments with limited resources.
Java Platform, Standard Edition (Java SE) — targeting workstation environments.
Java Platform, Enterprise Edition (Java EE) — targeting large distributed enterprise or Internet environments.

Download

Java is free to download. You can get the latest version at http://java.com.

If you are building an embedded or consumer device and would like to include Java, please contact Oracle for more information on including Java in your device.

Why must you stay updated?

The latest Java version contains important enhancements to improve performance, stability and security of the Java applications that run on your machine. Installing this free update will ensure that your Java applications continue to run safely and efficiently.

Overall JAVA is a must for internet users to ensure a rich and wonderful experience on the web !

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For developing enterprise applications Java is the best fit. As it is flexible object oriented programming language for robust enterprise application development. JAVA is having huge acceptability in building enterprise applications. JAVA is having worldwide acceptance and giant community. JAVA has replaced C++ in enterprise application development by its uniqueness of compiling and debugging the code. Java is very useful for not only developers but also for the end users because of its interactive, dynamic and neutral architectural quality. The end users can get live up to date content on the web. JAVA is having a wide community support which is helpful in solving all kind of problems with in very short time.

There are many benefits for using JAVA in enterprise applications. We know that enterprise applications are difficult to develop with sound object oriented knowledge. JAVA is platform independent that makes its favorable for enterprise applications. Some of very popular architecture Enterprise JAVA Beans (EJB) and Remote Method Invocation (RMI) has made JAVA as the best solution in enterprise application. One can run application on multiple platforms as JAVA easily adapts various platforms. JAVA software development makes sure of highly secured and easy coding. Java has well-designed, instinctive and multi tasking APIs that help in to do better-quality hassle free coding. For internationalization JAVA has some popular architecture such as Hibernate, CORBA, and Data Access Object (DAO).

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The Java virtual machine is called “virtual” because it is an abstract computer defined by a specification. To run a Java program,
you need a concrete implementation of the abstract specification. This chapter describes primarily the abstract specification of the Java virtual machine.
To illustrate the abstract definition of certain features, however, this chapter also discusses various ways in which those features could be implemented.

What ‘s the Java Virtual Machine?

To understand the Java virtual machine you must first be aware that you may be talking about any of three different things
when you say “Java virtual machine.” You may be speaking of the abstract specification, a concrete implementation, or a runtime instance.

The abstract specification is a concept, described in detail in the book: The Java Virtual Machine Specification, by Tim Lindholm and Frank Yellin.
Concrete implementations, which exist on many platforms and come from many vendors, are either all software or a combination of hardware and software.
A runtime instance hosts a single running Java application.
Each Java application runs inside a runtime instance of some concrete implementation of the abstract specification of the Java virtual machine.
In this book, the term “Java virtual machine” is used in all three of these senses. Where the intended sense is not clear from the context,
one of the terms “specification,” “implementation,” or “instance” is added to the term “Java virtual machine”.

The lifetime of a Java Virtual Machine

A runtime instance of the Java virtual machine has a clear mission in life: to run one Java application.
When a Java application starts, a runtime instance is born. When the application completes, the instance dies.
If you start three Java applications at the same time, on the same computer, using the same concrete implementation,
you’ll get three Java virtual machine instances. Each Java application runs inside its own Java virtual machine.
A Java virtual machine instance starts running its solitary application by invoking the method of some initial class.
The method must be public, static, return , and accept one parameter.
Any class with such a method can be used as the starting point for a Java application.

For example, consider an application that prints out its command line arguments:

// On CD-ROM in file jvm/ex1/Echo.javaclass Echo
{ public static void main(String[] args)
{
int len = args.length;
for (int i = 0; i {
System.out.print(args[i] + ” “);
}
System.out.println();
}
}

You must in some implementation-dependent way give a Java virtual machine the name of the initial class that has the method that
will start the entire application. One real world example of a Java virtual machine implementation is the program from Sun’s Java 2 SDK.
If you wanted to run the application using Sun’s on Window98, for example, you would type in a command such as:
java Echo Greetings, Planet.

The first word in the command, indicates that the Java virtual machine from Sun’s Java 2 SDK should be run by the operating system.
The second word, is the name of the initial class.must have a public static method named that returns and takes a array as its only parameter.
The subsequent words, are the command line arguments for the application.
These are passed to the method in the array in the order in which they appear on the command line.
So, for the previous example, the contents of the array passed to main,
The method of an application’s initial class serves as the starting point for that application’s initial thread.
The initial thread can in turn fire off other threads.
Inside the Java virtual machine, threads come in two flavors: daemon and non- daemon.
A daemon thread is ordinarily a thread used by the virtual machine itself, such as a thread that performs garbage collection.
The application, however, can mark any threads it creates as daemon threads.
The initial thread of an application–the one that begins at –is a non- daemon thread.
A Java application continues to execute (the virtual machine instance continues to live) as long as any non-daemon threads are still running.
When all non-daemon threads of a Java application terminate, the virtual machine instance will exit.
If permitted by the security manager, the application can also cause its own demise by invoking the method of class or .
In the application previous, the method doesn’t invoke any other threads. After it prints out the command line arguments, returns.
This terminates the application’s only non-daemon thread, which causes the virtual machine instance to exit.

The Architecture of the Java Virtual Machine

In the Java virtual machine specification, the behavior of a virtual machine instance is described in terms of subsystems, memory areas, data types,
and instructions. These components describe an abstract inner architecture for the abstract Java virtual machine.
The purpose of these components is not so much to dictate an inner architecture for implementations.
It is more to provide a way to strictly define the external behavior of implementations.
The specification defines the required behavior of any Java virtual machine implementation in terms of these abstract components and their interactions.
When a Java virtual machine runs a program, it needs memory to store many things, including bytecodes and other information
it extracts from loaded class files, objects the program instantiates, parameters to methods, return values, local variables,
and intermediate results of computations. The Java virtual machine organizes the memory it needs to execute a program into several runtime data areas.
Although the same runtime data areas exist in some form in every Java virtual machine implementation,
their specification is quite abstract. Many decisions about the structural details of the runtime data areas are left to the
designers of individual implementations.
Different implementations of the virtual machine can have very different memory constraints.
Some implementations may have a lot of memory in which to work, others may have very little.
Some implementations may be able to take advantage of virtual memory, others may not.
The abstract nature of the specification of the runtime data areas helps make it easier to implement the Java virtual machine on a wide
variety of computers and devices.
Some runtime data areas are shared among all of an application’s threads and others are unique to individual threads.
Each instance of the Java virtual machine has one method area and one heap. These areas are shared by all threads running inside the virtual machine.
When the virtual machine loads a class file, it parses information about a type from the binary data contained in the class file.
It places this type information into the method area. As the program runs, the virtual machine places all objects the program instantiates onto the heap.
As each new thread comes into existence, it gets its own pc register (program counter) and Java stack.
If the thread is executing a Java method (not a native method), the value of the pc register indicates the next instruction to execute.
A thread’s Java stack stores the state of Java (not native) method invocations for the thread.
The state of a Java method invocation includes its local variables, the parameters with which it was invoked,
its return value (if any), and intermediate calculations. The state of native method invocations is stored in an implementation-dependent way
in native method stacks, as well as possibly in registers or other implementation-dependent memory areas.
The Java stack is composed of stack frames (or frames). A stack frame contains the state of one Java method invocation. When a thread invokes a method,
the Java virtual machine pushes a new frame onto that thread’s Java stack. When the method completes, the virtual machine pops and discards
the frame for that method.
The Java virtual machine has no registers to hold intermediate data values. The instruction set uses the Java stack for storage of intermediate data values. This approach was taken by Java’s designers to keep the Java virtual machine’s instruction set compact and to facilitate implementation on architectures with few or irregular general purpose registers. In addition, the stack-based architecture of the Java virtual machine’s instruction set facilitates the code optimization work done by just-in-time and dynamic compilers that operate at run-time in some virtual machine implementations.

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It also puts Sun into the mainstream with other major platform developers such as Linux. While the company had put its Solaris operating system into open source status some time ago, Java is a highly distributed consumer platform and providing open source access to it gives the company a real boost in its standing among its peers. Perhaps more important, it will stimulate further development of consumer oriented Java-based programs. It is estimated that eight out of every ten cell phones have a Java application running on them.

A GPL use requires that any product developed under such licensure be returned to the “open source community” and remain, in effect accessible to all. Sun’s variation on this principle has an exception for applications built on the Java “Virtual Machine,” a platform that the company made available to software developers some time ago.

What this exception does is allow continued development of proprietary software written for Java, which keeps the language viable as a platform for revenue producing products. Prior to the switch to GPL status, Java program developers had to pay a licensing fee to Sun.

IBM has been after Sun to take Java to open source status for years. Their Works Projects has been a center for the development of open source products, primarily based on Linux. From their perspective, Sun’s decision to grant GPL status for Java is viewed as an opportunity to unite with Linux and provide a stronger platform to challenge Microsoft. The politics of software can be enormously complicated, especially when there’s an elephant like Microsoft in the house. But what Sun has accomplished with this move is provide an opportunity for programmers to zero in on Java products as potentially large revenue sources.

Unlike Linux, which was spun off of UNIX to provide an alternative to Windows, Java stands in a class of its own. While Linux has survived in the marketplace, it has never mounted a major challenge to Windows. Java’s unique qualities and the intellectual property that protects those qualities will now be an open book for programmers developing new applications.

It will also provide the opportunity to bundle Java products with Linux based software. Sun’s internal interest in this move is to stimulate more developers to use the language, in order to revive its own internal software business. Since taking a huge hit in their high-end server market, Sun has been struggling to find a new path and has increasingly looked to software as an opportunity.

Sun’s EVP for software summed up the value of the move for the company and its product. “People have been hesitant to distribute Java worldwide with Linux (distributions) because of (concerns over) license alignment,” Green said. “This is the last gate to ensure that Java will be distributed worldwide.”

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All our Java Developers are well qualified with excellent communication and analytical skills and with considerable experience in their respective areas of expertise.

Developers are equipped with high end Workstations with the latest software and tools installed for constancy in their work. All communication channels like MSN, Yahoo, AOL, and SKYPE are available with the developers for easier transfer of information & communication during projects.

Why Aegis:

Continuous commitment to Java platform since the foundation of our company, which makes us the best choice of an expert in Java development and integration solutions.

A motivated team with a strong technical background and commitment to excellence, which ensures efficient work and delivery of high-quality software. We undertake projects both large and small and tailor the solution to meet the budget and the deadlines. Java has many advantages, not least of which is that there are many open source projects that provide industrial-strength foundations on which to build cost-effective solutions.

our Java expertise was complemented by a broad range of experience. Today we operate in a spectrum of sectors and are able to bring a depth of knowledge to all our projects. We offer Dedicated Development Services & Consultancy on Java Platform. At Aegis we have pool of Expertise to get any size Big or Small Java application done.

As the leading international provider of Java software technology in India we are committed for best services and solutions on Java Platform.

Technologies and Tool we work On:

Java EE, Java SE, JNI, EJB, JPA, XML, Spring, Hibernate, TopLink, OSGi

Apache Axis, Codehous xFire

JSP, Servlets, JSF, Struts, WebWork, Ajax, JavaScript, XHTML

Swing, SWT

Oracle, DB2, Microsoft SQL Server, SAPDB, PostgreSQL, MySQL, FireBird, Derby, Hypersonic

PL/SQL, Transact-SQL, Oracle Forms

ERwin Data Modeler, BPwin, PowerDesigner 6.0—12.0

IntelliJ IDEA, Eclipse, Ant, Maven, Cruise Control, TeamCity, Hudson

JUnit, TestNG, Emma, Clover, Selenium

Apache Tomcat, JBoss, Weblogic, WebSphere, Orion, Resin, Oracle Application Server

Qualifications of our Java Developers

Qualifications of JAVA, J2EE Developer

4-year college degree in computer science or 3 Years Masters Degree

Software Development Life Cycle Experience

Extensive exposure to JAVA, J2EE, J2ME

JBoss, Tomcat, Apache, IBM Web sphere, Oracle Application Server, Struts, Beans, EJB, Ant

XML, Web Services, XSLT

J2ME, Xlet, Java Foundation Profile, Java CDC

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Java is widely use for web development application. It provides effective portability and scalability to meet the growing needs of people using Internet. To name the few one can play online games, chitchat with their friends, colleagues or business associates, calculate mortgage interest, or have a look at 3 D images. Java technology has been able to provide:

* Versatility

* Efficiency

* Security and Networking

* Platform portability

In a developed country a professional charges hefty fees for making java application software. But in developing country like India for Java services, the vendor can charges quite less without comprising about the quality. Some of the reasons for going ahead and partnering with an outsourcing java service vendor are:

* Economical Solutions – There are many companies offering with Java development services at competitive cost. Hence, you can choose the one that suits your needs well.

* Knowledgeable manpower – Knowledge is power. Same thing goes for java developers. They are the expert and understand the importance of quality and timeliness of the work. Hence you can completely depend on them to get quality output. They build, manage and promote the clients business, so that they can reap high profits.

* Strategic Approach: The company who is handling your outsource work strategically works to reduce customers cost, moderate risk and recommend the necessary solutions.

* Complete testing and risk analysis: Before the final product and services is delivered, they are completely evaluated on basis of functionality, performance, and integrity.

To know more about companies offering outsource java services, visit:

<a rel=”nofollow” onclick=”javascript:pageTracker._trackPageview(‘/outgoing/article_exit_link’);” href=”http://www.icreonglobal.com/java-development.shtml”>Application Development Using Java</a>

<a rel=”nofollow” onclick=”javascript:pageTracker._trackPageview(‘/outgoing/article_exit_link’);” href=”http://www.icreonglobal.com/java-development.shtml”>java developers India</a>

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Java has significant advantages compared to other languages. Java language is easy to use and therefore easy to write, compile, debug. Moreover, it is easier to learn when compared to other programming languages. Since Java is object-oriented, it allows you to create modular programs and reusable codes. Platform-independent, Java is a robust language. The language lays more importance on early checking for errors, since Java compilers can detect many problems during the time of execution of an application. Java is multithreaded, since it has the capability for a program to perform several tasks simultaneously within the same program. Java Development has gained a significant position in the industry with programmers and developers finding it easier and more effective than many other languages.

Java applications are designed to be compiled and then interpreted at runtime, unlike the conventional programming languages, which can either compile source code to native code or interpret the source code. The language itself has borrowed the syntax from C and C++. Java considers security as a part of its design. The Java language, its compiler, interpreter, and runtime environment are all developed with security. Writing network programs in Java is similar to sending and receiving data to and from a file.

The Java programming language was developed and re-designed for use on the Internet. In the internet domain, Java’s popularity has increased tremendously, especially on the server side of the Internet. Nowadays, there are a large number of Java experts who strive for the enhancement and improvement of Java development. For beginners who are interested in learning Java, the numerous Java tutorials available online are good to start with. Java tutorials and Java tips are the best resources for learning and improvising in Java.

Java Development experts are trying to enhance their programming skills for writing secure Java applications. In order to write a secure code in Java you need to be aware of various things such as data handling techniques, user authentication rules, access controls etc. JavaScript is a scripting language which shares a similar name and has the same syntax, but is in no way related to the core Java language. Few steps are crucial for a secure Java application development. They are logical software design, proper validation, well planed application development and standardized security test. Java has become the language of choice world over for providing effective and sure-fire Internet solutions.

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