Information in a java program is organized in a specific way. The smallest and simplest java program can only execute if it is coded as a .java file. When a .java file is created, it must contain at least one class. A java class contains specific information such as variables and methods. A single java file is generally structured similarly:

public class Greeting

{

int someVar = 0;

public static void main(String[] args) {

System.out.println(“Hello, world!”);

}

}

In this classic “Hello, world!” output, the class Greeting is defined. A .java file must contain and define at least one class. A class can be controlled by methods defined within it. In this example, a special method main will try to show the output “Hello, world!” when the class is loaded. A class may contain fields such as the integer type of variable declared as someVar, with the value of zero. As each .java file should have one class, it should also have one class that has the main method. Greeting, someVar, and main are called identifiers. An identifier labels entities in a java program such as a class, a variable, or a method. The class Greeting is a public class. Each java file can have many classes but only one can be declared public. Note also that the method main is public, and static.

Many .java files may be actually needed to run a more complex program. Similarly, some methods and classes are meant to be reused in some other way for various programming applications. In this case, it is best to organize .java files according to their use, and group programs that generally work for the same kind of output. If a greetprogram.java file contains:

package sayinghello;

public class Greeting

{

public static void main(String[] args) {

System.out.println(“Hello, world!”);

}

}

Here, the Greeting class is bundled to a package called sayinghello. The keyword package must be at the first line of a .java file. Classes from the sayinghello package can be used by classes from another program by using import:

//this is a file saved as mymeeting.java

import sayinghello;

public class Meeting

{

public static void main(String[] args) {

sayinghello.Greeting();

System.out.println(“Nice to meet you, goodbye!”);

}

}

By importing the saying hello package, this simplifies the need to re-code the entire “hello world” program. The commonly used programs are already packaged for easy access for programmers, they usually come bundled with software development kit (SDK). The open-source community thrives in collaboration and sharing, packages help keep even large and complex programs from chaos. In even more complex programs, packages may need to interact with other packages. Packages can also contain packages within them, which are called subpackages.

Lastly, packages and subpackages are stored in the file system within folders and sub-folders respectively. An entire collection of packages and subpackages can be archived into a single file called a java archive. The file extension .jar is associated with a java archive.

Some mobile devices such as Cellular phones and PDAs that use the Java 2 Platform, Micro Edition (J2ME), require a pair of files to run a java program. Aside from the collected .jar file, a second file called a Java application descriptor (.jad). The .jar and .jad, together encompasses a MIDlet suite. A .jad file is not part of the program itself, but it supplies additional information or metadata to describe the actual program contain in the .jar file.

A java program can be created using simple text editors such as the ubiquitous Notepad in Windows or TextEdit in Macs. Such programs are called editors. Editors cannot execute the programming code written on them. They are simply means of storing the program for future execution. There are other computer software that can be used to specifically aid a java developer to create and edit and manage complex and elaborate codes and algorithms. These programs offer a variety of features, to help a Java programmer organize their codes and files. A java program is a file with the “.java” extension (i.e. myJavaProgram.java). A Java program requires compilation using a program called a Java compiler. What a Java compiler does is to interpret the human-readable code written in the .java file and covert it to a file in bytecode. Basically, the human-readable instructions typed in a .java file are called a source code.

By using a java compiler, these instructions are converted and stored in bytes. Each of the class included in a java source code are separately encoded to a corresponding class file. For example, a .java file defining two classes- myClass and myOtherClass will compile into two files in bytecode, with the names myClass.class and myOtherClass.class, respectively. Files saved as .class lose their human readability, but are more compact and easier to distribute. However, there are ways to reverse engineer .class files back to a human-readable source code. Reverting bytecoded files back to its source code can be done by using decompilers. Decompilers themselves are not meant to steal the original codes of a program. As such, care and ethical concerns should always be considered when attempting to reverse engineer and extract information from someone else’s hard work.

It is also during compilation that the program is checked for errors. Syntax errors can occur when the compiler encounters parts of the code that it cannot recognize. Compilers will not produce a class file for as long as it has these syntax errors. Source codes can only be allowed to compile without these syntax errors. A successfully compiled .class file is no t guaranteed error free. A logical error can occur but the compiler will ignore it simply because it can understand the code. Common logical errors include mistakes in string values or mathematical expressions. These are human errors does not interfere with the ability of the program to execute, but they generally make the program provide an unexpected behaviour or output. Debuggers are applications that help developers to watch and trace a program as it traverses its designed algorithm. Debugging is not integrated in the steps needed to run a java program. However, debuggers are one of the most important tools used by programmers to ensure that their programs would run the way they are designed to be, and not just run simply for the sake of it.

After obtaining the compiled .class files from the source code, the program is one step closer to becoming machine readable. The personal computer used by people everyday is collectively a machine. In order for the machine to perform tasks, it must receive information in bitwise machine code or machine language (i.e. sequences of ones and zeroes). As a final step, .class files are relayed to the actual machine by another program called a virtual machine. A virtual machine will verify, interpret and the java byte code file as though it is an actual machine receiving instructions in machine language. The Java Virtual Machine (JVM) is also known as the Java Runtime Environment (JRE). This software allows Java programs to be executed on an actual machine, such as the personal computer or a mobile phone. Being a virtual machine, it bridges the program to the actual machine’s environment and resources. It also ensures that the program is contained in its environment and prevents the program from directly interacting with the actual machine’s operating system or hardware through malicious codes or erroneous instructions. At this stage, the program is now finally “running” and is now able to give instructions to the virtual machine.

Java is a computer language that was primarily designed to be simple and also architecturally neutral. During its early years, the language was promising but at that time there was still no market for it. In 1995, what the developers did was to introduce Java at the Sun World exhibition. Programmers were enthusiastic about the simple language and the richness of its library. This meant that more and more portable programs could be written that could bypass proprietary operating systems.

Java offers micro and enterprise editions of its library which make the programmers comfortable on any hardware. There is a vast range of this from simple gaming devices to the largest internet providers. In this article, what would be focused on would be the benefits of Java’s superior performance and its security features.

Java programs are grouped to a portable intermediate form that we know now as byte codes. This is similar but of a newer form of the machine-language instructions. Java Virtual Machine has a program that could be used so as to interpret these portable byte-code commands. Make-up and form of Java programs meant that they process at a higher speed compared to scripts and programs which are written in interpreted languages. The only problem here is that they are somewhat slower than C and C++ programs.

There is one thing that users must remember, that although Java programs are compiled to byte code, the interpreted byte codes does not cover up the totality of Java platforms. Portions concerned with intensive computations of the Java platform like string-manipulation methods are being used with older versions of machine code could be implemented using the older version of the machine code to ensure its efficiency.

It is true that the earlier versions of Java suffered from some problems with its performance. Through the years, the program has greatly improved. Almost every year, it comes with a new release that further progresses the speed of Java VM. Its performance is no more its biggest problem.

The VM has undergone significant changes to make it highly developed and optimized. Many developments include a just-in-time compiler; this development is capable of converting Java byte codes to an older version of machine commands. Java programs are also equipped with JIT compilers; this helps the system perform at speeds that are as good as or even better than C and C++ applications.

Many programmers avoided it before due to glitches in performance. With the advances made in Java 1.2, more and more use it. It is a perfect combination of performance and manageability.

The language and the platform of Java were designed from the ground up with security as one of the primary design concepts. Users are allowed to download unsecure codes over the network with the help of the Java platform. It is still safe to use because you could run it in a secure environment. At this state, the host system will not be affected or infected by a virus and many other sorts of problems. The Java platform’s capacity by itself makes the system one of a kind.

By the introduction of Java 2 Platform, security models went up a notch. This development made the security levels and restrictions highly configurable and broadens them further than just being applets. With Java 1.2, all the Java codes like the applet, the JavaBeans component, or complete applications can be run with highly restricted permissions and helps protect the host system from being harmed by these.

Java’s language and platform’s security features underwent thorough analysis by various security experts that came from all parts of the globe. This ensured the security. Some security-related bugs were found in the system and swiftly fixed. This made a big noise especially when a new security bug is found. Other mainstream platforms available in the market are not able to create security guarantees that Java could offer. This is one big reason behind its popularity.

Even if Java holds the best security promises there are still some features that need improvement. Even if that is the case, Java gives the assurance that it is well suited to be used on practical and simple every day applications. In the market, you will not find other alternatives that are up to par with what Java can offer and do.

The memory size is a significant aspect in the development of embedded systems. Programmers try to reduce the size of the generated compilation of codes through the use of compiler optimization techniques. This method is known as procedural abstraction.

Procedural abstraction is mainly used for optimizing code size. In the process, the repetitive instances of similar code fragments are grouped into new subroutines. During the early methods of programming, procedural abstraction is used on the primitive levels of the machine code in optimizing linkers and binary rewriting tools. A procedure is used to compile codes. It then provides an interface for the code through a formal parameter list and a mechanism for transferring parameters.

There are two types of procedural abstraction. Abstraction by parametrization skips the identification of the provided actual parameters used in the calling procedure. On the other hand, the specification technique provides abstraction from details of implementation of a procedure. Since a procedure has its unique piece of code with well-defined entry and exit points, a specification can be created for the specified code. A code specification defines the functions of the procedure without giving the details of how the procedure is implemented.

Top down. Top down programming is highly recommended in software development. The top down approach implements structural hierarchy on the programs design. The top down approach can be summarized into two stages: (1) defining the solution from the highest function level and (2) narrowing it down into smaller routines. Eventually, the components would be specific enough to be coded for the compilation of the program. Top down programming facilitates easier coding and documentation. It is the exact opposite of the bottom up programming technique, which is a very common approach in object-oriented programming languages such as Java.

The top down approach allows the programmer to give emphasis on the planning and provides a complete comprehension of the system. This method does not allow any coding to begin unless the appropriate level of detail has been met in the design of a certain part of the system.  However, the top down technique attaches stubs in place of the module and waits until the significant design completes; a process which may cause delay in testing of the critical functional units of the system.

Java is one of the commonly used object-oriented programming languages. It is developed specifically for creating distributed programs on shared networks and on the World Wide Web.

Programming is often seen as the integration of logical statements, not as the process of defining data. The concept used in object-oriented programming is about focusing on the objects to be manipulated rather than the logic to be applied in the process. The objects involved in the object-oriented programming range from human beings (defined by name, address, and so forth) to locations (whose properties can be specifically defined and managed) and even tools that you use on your computer (such as navigation bars and action buttons). In a program using the object-oriented approach, the procedures are logically arranged to take input data, apply the definite process and then produce a data output.

In an object-oriented programming, all the objects to be manipulated are identified. These objects are compared to each other for any relation between them, a process known as data modeling. The identified objects are generalized into ideal classes and are verified for the data it contains and which logic sequences are applicable for the manipulation. A distinct logic sequence is defined as a method. The instance of a class or “object” provides instructions and the class characteristics give the relevant data. Object orient programming uses well-defined interfaces or messages for the user and the manipulated objects to communicate with each other.

An object-oriented programming has its advantages. Inheritance of class attributes provides a more detailed analysis, which greatly helps in reducing development time and avoiding unexpected errors in the coding. The uniqueness in the class instances provides additional security which is helpful in avoiding cases of data corruption. The repetitive use of definitions in different programs makes it more suitable for network distribution. The data classification concept allows the creation of any new data type that is not yet defined on the programming language used.