A search on
'What is Java' in google returns roughly about a billipon pages. That is
the popularity of Java on the web. If you haven't read the history of Java
please read it first here.
Java was just meant to be a portable, platform independent programming
language. But over the years it has transformed into a complex platform
for computing portable software across different devices and systems.
What is the need for
When there were so many
programming languages already available what was the need for another
To understand this let us
take an example of a program that runs on a SONY TV remote control. This
program can be written using a language (let us assume) called X.
The remote control has an in-built chip on which this program will run. If
we look at the functionality of a TV remote it is almost the same for any
brand of TV. So by right the same program should be used on any brand of
reality it is not. Why? Because the in-built chip in different brand of TV
Remotes maybe different. Therefore the same program has to run these two
different chips, they have to be re-compiled in order to suit different
chips in other words platforms. If there are 100 different brands, the
same program has to be re-compiled 100 times to suit these 100 different
brands. This is where the problem arises. That is why a new programming
language was needed. And Java was the answer.
How does Java solve
The Java designers came
out with a wonderful concept of a 'Java Virtual Machine'. Now Java differs
from rest of the languages in using this unique concept. Which means
unlike other languages a Java program when compiled produces a ByteCode
rather than machine code. This ByteCode is machine independant (platform
independant). The Java Virtual Machine resides on the machine and
interprets this ByteCode into a form the machine can understand.
Now take the same example
of a TV remote. If the program was developed using Java rather than X,
then the same program can be used in all different brand of TV Remotes provided
all of them have the 'Java Virtual Machine' (JVM) installed on them.
If all of them have the JVM the JVM will convert this same program into a
form that each brand of TV remote understands. This is a very simple but
effective method of making a program portable. This is how Java solves
Now that we understand
what is Java, move on to the Java
getting started guide