Learning JAVA for
beginners …
Salute,
I am Nikhil
Here you will learn java in simple steps like a beginner
So let's start java… with live example for creating simple
and interesting games…
For running java you have to install small software named
JAVA SDK
you know java is platform independent …
What is JDK (Java Development Kit) ?
JDK is a software development program provided by
sun Microsystems. Java Development Kit or JDK comes in various versions and can
be downloaded free from the sun Microsystems. JVM compiler, debugger and other
tools are used with JDK for developing java based application & java
applets. So make sure that your JVM compiler & JDK versions are same.
JDK also known as Java 2 Platform That comes in
three editions J2ME, J2SE & J2EE. If you are beginner or learning Java then
start by downloading J2SE.
Acronyms:
JDK Java Development Kit
JVM Java virtual machine
Download JDK
you can download JDK from www.javasoft.com/j2se
Latest version of JDK
1.
JDK 5.0 Update 6
the full internal version number for this update release is 1.5.0_06-b05 (where
"b" means "build"). The external version number is 5.0u6.
Java Version 1.5.0_06 introduces various security enhancements in Java Plug-in
and Java Web Start to better protect users and enterprises. For more
information please visit: http://java.sun.com/j2se/1.5.0/ReleaseNotes.html
SO let's start learning java particles…
The first program we are going to learn is a simple java
application "Hello Java"
in which you create a program and run it then it will show a
message …
So The first step is Open your notepad and type this
program,
//Simple java application…
public class Hellojava
{
public static void main (String [] args)
{
System.out.println("Hello ! Java");
}
}
I suggest you to type this program
by your own without seeing this…
Now save this notepad file as
"Hellojava.java"
The point is, you have to save
this file by the class name which you have given in the program and you have to
use the .java extension
Setting the path
Now you have to do an important
task is to set the path for java
So let's start .
First Step
Go to run type sysedit
Now type this in the AUTOEXEC.BAT
file
SET
PATH=C:\WINDOWS\COMMAND;C:\JDK1.3.1\BIN
Or if you install jdk in another
drive then give that path…
now save and exit
Running Application
Open command prompt go in the
drive (where you save your notepad file)
Then type__
javac Hellojava.java
now run your application__
java Hellojava
![Hellojava.JPG]()
a message will seem "Hello ! Java"
What you did !
Line
of code is a blank line, which as you might imagine, does nothing.
Following
that is the beginning of your program class definition:
public class HelloWorld {
You
must define a class in every Java program. Basically, a class is a group of
functions
and
characteristics in Java code that can be reused. The public
keyword,
used
as a modifier that describes other classes' access to this class, is not
required,
but it is a good idea to use it anyway. This way you will start off with
good
coding habits. It is not necessary at this point to fully understand the public
keyword.
The
same goes for the class keyword. It
is used to identify Hellojava as a class.
The
open brace denotes the beginning of the contents of your class definition
and
the corresponding closing brace (the last line of the program) denotes the
end
of the class definition. To sum it up, this line of code starts a Java program
called Hellojava,
and all the code within the braces makes up its guts.
.
The
next line of code starts the main() method
definition.
public static void main(String args[]) {
Methods are groups of
statements that are executed by your computer when
instructed
to do so. You learn about methods in Chapter 5. For now, it is important
that
you know that the main() method
actually drives Java applications. It is
the
first place the Java VM looks when you run your application. The group of
statements
within this method, collectively called a block
statement, is defined
within
its own set of braces. Within the braces of this method, you define a list
of
steps you want the computer to do when running your program.
The
one statement inside the main() method, which
is your next line of code,
instructs
your computer to say hello to the world.
System.out.println("Hello,
world!");
This
is actually a call to a method that handles your system's standard output. It
prints
one line to the screen and adds a carriage return. You can refer to the Java
API
documentation for classes System and PrintStream for more detailed information
Congrats ! now you know the syntax
and knowledge about JAVA
Thanks
Nikhil Kumar