Create First Program in Java

Create First Program

In this section, you will learn to write a simple Java program. For developing a java program you just need a simple text editor like "notepad".

Open the notepad and write your program.

Let's create a class createfirstprogram that will print a message "Welcome to RoseIndia.net" on the console.

Here is the code of createfirstprogram.java file:

class createfirstprogram{

      public static void main(String[] args) {

        System.out.println("Welcome to RoseIndia.net");

      }

    }

Save this program in the specified directory ("C:\Vinod" in this example) with name createfirstprogram.java.

This class contains public, static and void java keywords (these are pre-defined words in java which carries specific meaning).

public keyword specifies the accessibility issues of a class. Here, It specifies that method can be accessed from anywhere.
static keyword indicates that this method can be invoked simply by using the name of the class without creating any class-object.
void keyword specifies that this method will not return any type of data.
main() method is the main entry point of the program, to start execution. First of all JVM calls the main method of a class and start execution . JVM (Java Virtual Machine) is responsible for running java programs.
args is a string array that takes values from java command line. It's index starts from '0'. We can access values by writing args[0], args[1] etc.
println() function prints the output to the standard output stream (monitor).
out represents the standard output stream (monitor).

Now, you are ready to compile and run this program. Open the command prompt and go to the directory ("C:\vinod" in this example) where your program is saved.

Java uses the "javac" command to compile your program (Type javac createfirstprogram.java) . After compiling successfully, you can run it. Java uses the "java" command to execute your program (Type java createfirstprogram). It will print "Welcome to RoseIndia.net".

Output of program:

C:\vinod>javac createfirstprogram.java

C:\vinod>java createfirstprogram
Welcome to RoseIndia.net

C:\vinod>_

Current Comments

12 comments so far (post your own) View All Comments Latest 10 Comments:

Hi...beautifully illustrated....I got the success..:-)

Posted by Sharad on Friday, 01.30.09 @ 13:03pm | #84335

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hi ter hope any one would help me to fix this...
thank u

Exception in thread "main" java.lang.NoClassDefFoundError: createfirstprogram
va
Caused by: java.lang.ClassNotFoundException: createfirstprogram.java
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
Could not find the main class: createfirstprogram.java. Program will exit.

Posted by vas on Friday, 12.12.08 @ 00:17am | #82666

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Need to learn how to create databases and manipulate them in JAVA

Posted by Langson on Thursday, 11.13.08 @ 08:50am | #81645

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This site is excellent all the tutorials and speciall interview questions.

Posted by neetu on Thursday, 10.30.08 @ 04:32am | #81402

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Exception in thread "main" java.lang.UnsupportedClassVersionError: Divya (Unsupp
orted major.minor version 50.0)
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)

Posted by anjali on Tuesday, 09.9.08 @ 05:23am | #78144

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Firsttime I run a program confidently .It worked greatly for me.Thanks RoseIndia.net

Posted by Praveena on Wednesday, 08.13.08 @ 15:29pm | #72633

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i was amazed when i had seen such a good lucid understanding site with all the java stuff its really amazing world to learn!!!!

Posted by RAKESH.S on Wednesday, 05.21.08 @ 16:09pm | #60592

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This didn't tell me anything and the program didn't work!

Posted by Marty on Monday, 04.28.08 @ 07:18am | #58026

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in java how to connect two forms without making any validation. pls if possible send me the code. its very urgent.