Java technology is:
• A programming language
• A development environment
• An application environment
• A deployment environment
• It is similar in syntax to C++.
• It is used for developing both applets and applications.
Java is an object-oriented programming language developed by Sun Microsystems. Originally the developers of Java intended to use C++ for their software development. But they needed a language that could execute on different sets of computer chips to accommodate the ever-changing consumer electronics market. So they decided to design their own language which would be independent of the underlying hardware.
It allows a user to receive software from a remote system and execute it on a local system, regardless of the underlying hardware or operating system. An interpreter and runtime are called the Java Virtual Machine which insulates the software from the underlying hardware.
Unlike more traditional languages, Java source code does not get translated into the machine instructions for a particular computer platform. Instead, Java source code (.java) is compiled into an intermediate form called bytecodes which are stored in a .class file. These bytecodes can be executed on any computer system that implements a Java Virtual Machine (JVM). This portability is perhaps one of the most compelling features of the Java language, from a commercial perspective. In the current era of cross-platform application development, any tool that allows programmers to write code once and execute it on many platforms is going to get attention.
2. Java Language Characteristics
• The portable, interpreted nature of Java impacts its performance. While the performance of interpreted Java code is better than scripting languages and fast enough for interactive applications, it is slower than traditional languages whose source code is compiled directly into the machine code for a particular machine. To improve performance, Just-In-Time compilers (JITs) have been developed. A JIT compiler runs concurrently with the Java Virtual Machine and determines what pieces of Java code are called most often.
• The bytecode portability is what enables Java to be transported across a network and executed on any target computer system. Java applets are small Java programs designed to be included in an HTML (HyperText Markup Language) Web document. HTML tags specify the name of the Java applet +and its Uniform Resource Locator (URL). The URL is the location on the Internet at which the applet bytecodes reside.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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