Java is purely an object oriented programming language developed by James Gosling at Sun Microsystems, which is a supporter company of Oracle Corporation. Java’s most of the syntax and semantics are derived from C and C++. Java source code is first compiled into bytecodes which results in a class file, then the class file can be run on any Java Virtual Machine (JVM). Bytecodes are a set of machine instructions which are not specific to any one processor.
Java is a platform independent and portable language because of “Write Once, Run Anywhere” feature. The Java programs written once should run similarly on diverse hardware.
The software Java Runtime Environment (JRE) is required to run java applications. Java Development toolkit (JDK) is a superset of JRE, which includes development tools, Java compiler, Javadoc and debugger.
Java Development has 2 parts:
1) Java Compiler
2) Java Interpreter
Compiler converts java code to a bytecode, interpreter executes the bytecode with the help of JVM. Debugger helps to find and fix the bugs in java programs.
Java is very successful for developing server-sided applications including: web services and EJB.
An applet is a java program which consists of bytecode. Java applet runs in a web browser using JVM. Applets provide interactive features to web applications which cannot be provided by HTML alone.
A servlet is a server sided java programming, which extends the capabilities of servers using a request-response programming model.
JavaBeans are reusable component for java. They are classes written in the Java language. Beans encapsulate many objects into a single object and it is passed around as a single bean object instead of multiple individual objects.
Java has built-in support for multi-threaded programming; with this it is possible to write programs that can do many tasks at a time. This feature is helpful in building interactive applications.
Java Server Pages is a technology to create dynamic web pages based on HTML, XML. JSP makes use of component based approach which helps to easily combine static HTML with look-and-feel java component to develop dynamic pages.
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