JAVA PROGRAMMING

2007-11-12T18:25:00.000-08:00

Java is a programming language. It is also a platform

JAVA PROGRAMMING

The Java programming language is a high-level, object oriented language. It is a third generation programming language like C, Fortran, Perl, and many others. You can use Java to write computer applications that support many functions.

Java is most similar to C++. You can develop web applications using java.

You can access Databases using Java Database Connectivity JDBC.

JAVA PROGRAMMING USING JDBC

JAVA has a virtual machine. It is a piec of software that runs java applications.

A platform is the hardware or software environment in which a program runs. Most platforms can be described as a combination of the operating system and underlying hardware. The Java platform differs from most other platforms in
that it's a software-only platform that runs on top of other hardware-based platforms. The Java platform has two components:
The Java Virtual Machine : A JVM is a piece of software that is responsible for running Java programs. The JVM is an
abstract computing machine and (just like a real computing machine) has a defined instruction set. The JVM knows
nothing of the Java language, only of a particular file format, the class file format. A class file contains JVM
instructions (or bytecodes) and a symbol table, as well as other required information. It interprets the bytecodes that are written by the Java compiler appropriate for the platform.

The Java Application Programming Interface (API) : The API is a large collection of ready-made software components that provide many useful capabilities. The Java API is a rich set of predefined classes that you can reuse in your programs to make your programming life easier.

ADVANTAGES OF JAVA :

1) JAVA IS SIMPLE :
Java was designed to make it much easier to write bug free code.Because Java is simple, it is easy to read and write.The language is small so it's easy to become fluent. The language is interpreted so the compile-run-link cycle is much shorter. The runtime environment provides automatic memory allocation and garbage collection so there's less for the programmer to think about.Finally, it's very difficult (if not quite impossible) to write a Java program that
will crash your system, something that you can't say about any other language.

2) JAVA IS OBJECT ORIENTED :
Object oriented programming is simpler and easier to read programs. It is more robust and error free. And to top it
all, it is more efficient reuse of code.

3) JAVA IS PLATFORM INDEPENDENT :
Java applications consist of byte-code which may be interpreted by a virtual engine. Thus, the applications are able
to run on any hardware for which a virtual engine exists.

4) JAVA IS SAFE :
There are no pointers in JAVA. Java programs cannot access arbitrary addresses in memory.Java implements a
robust exception handling mechanism to deal with both expected and unexpected errors. The worst that an applet can do to a host system is bring down the runtime environment. It cannot bring down the entire system. Java, by
making it easier to write bug-free code, substantially improves the security of all kinds of programs.

5) JAVA IS HIGH PERFORMANCE :
Java byte codes can be compiled in speed using a "just-in-time compiler". It is certainly possible to write large
programs in Java.

6) JAVA IS MULTI THREADED :
Java is inherently multi-threaded. A single Java program can have many different threads executing independently and continuously. This makes Java very responsive to user input. It also helps to contribute to Java's robustness and provides a mechanism whereby the Java environment can ensure that a malicious applet doesn't steal all of the host's CPU cycles.

7) JAVA IS DYNAMIC :
Java does not have an explicit link phase. Java source code is divided into .java files, roughly one per each class in your program. The compiler compiles these into .class files containing byte code. Each .java file generally produces
exactly one .class file. More importantly, classes that were unknown to a program when it was compiled can still be loaded into it at runtime. Furthermore, Java .class files tend to be quite small, a few kilobytes at most. It is not necessary to link in large runtime libraries to produce a (non-native) executable. Instead the necessary classes are loaded from the user's CLASSPATH.

8) JAVA IS GARBAGE COLLECTED :
You do not need to explicitly allocate or deallocate memory in Java. Memory is allocated as needed, both on the stack and the heap, and reclaimed by the garbage collector when it is no longer needed. There are constructors and
these do allocate memory on the heap, but this is transparent to the programmer.