In software development the greatest challenge for software developers is a tool that is consistent and can be deployed anywhere and on any platform. Such a tool also needs to play well with other applications. Such dynamic applications that take advantage of networks and that can be upgraded and extended seamlessly have been a long time in coming. However, with the coming of Java, things seem to have changed and the enthusiasm that Java has generated is for a good reason. Initially used to build embedded applications for the web called applets, java has also become the premier platform for building other web applications such as networked applications and user interfaces that take advantage of current web standards.
Java is a compiled and an interpreted language. What does this mean? It means that the Java source code is turned into binary instructions into a universal format and the complied byte code executed by a runtime interpreter or a java virtual machine. Java specifies all implementations and does not leave anything up to the platform from where it is running. In other words, java code is implicitly portable. You do not have to produce alternative versions of an application to run on different platforms with Java. Its interpreter is also relatively small and can be embedded on any software such as a web browser.
The Class is the fundamental unit of Java code. Classes hold executable code and data and are distributed in a universal binary format. Classes are also maintained locally and can be dynamically loaded at runtime from a network server when an application needs them. Because the Java interpreter runs compiled byte code, this language is considered to be relatively fast. Even more important is the fact that software implementations can compile byte code on the fly to the native machine. This is called dynamic compilation and ensures that Java code is nearly as fast as the native while maintaining security and portability. In laymans language, Java code can run as fast as the static compiled program code on the same machine.
Well, what makes Java code relatively fast? If you look at the time programs spend doing, it turns out most of that time is spent executing relatively small parts of code that are repetitive. While these chunks of code may be small, they determine the overall performance of a program. Java is able to compile those sections into true machine code while leaving the rest of the program uncompiled just interpreted saving time and memory and as a result dramatically improving performance. While the technology is complex, the idea is essentially quite simple. Optimize parts of the program that need to go fast and leave the rest. Undoubtedly, when it comes to portability and speed, Java is the language of choice.