Guide [Java] Your First Java Program

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Your First Java Program

 

So today I'm going to teach you how to write, compile and execute your first java program. It is a simple program to display "Hello Hack Community" as the output.

 

What do you need?

You need nothing but JDK installed in your machine. We are going to write our code in Notepad and compile it via command prompt.

 

Step 1

Write the following code in a new blank Notepad document.

class HelloHC
{
        public static void main(String args[])
        {
                 System.out.println("Hello Hack Community");
        }
}

 

Step 2

 

Save the code in your projects folder.

 

Make sure you save the file with same name as the class name (HelloHC in this case) and with an extension of .java

 

Select the type All Files instead of Text Documents(*.txt).

 

 

Step 3

 

Now it is time to compile your code. Navigate to your projects folder using command prompt.

 

Type in the following command

javac HelloHC.java

If you did not get any error message, then your file has been compiled successfully.

However, if you get an error message :

'javac' is not recognized as an internal or external command,
operable program or batch file.

You need to add the path of JDK's bin directory.

path [Drive:]\[Path of jdk\bin Directory]

This would be followed by the former command you gave i.e. javac HelloHC.java

 

After compiling your code successfully, a new file would be created in your projects folder with same name HelloHC.class

Now in order to execute the code you just compiled, just type in the following command

java HelloHC

 

Congratulations! You just executed your first Java Program!

Cheers :)

 

 

Updating the PATH Environment Variable

 

You can run the JDK without setting the PATH environment variable, or you can optionally set it so that you can conveniently run the JDK executable files (javac.exe, java.exe, javadoc.exe, and so forth) from any directory without having to type the full path of the command. If you do not set the PATH variable, you need to specify the full path to the executable file every time you run it, such as:

 

C:\> "C:\Program Files\Java\jdk1.7.0\bin\javac" MyClass.java

It is useful to set the PATH variable permanently so it will persist after rebooting.

 

To set the PATH variable permanently, add the full path of the jdk1.7.0\bin directory to the PATH variable. Typically, this full path looks something like C:\Program Files\Java\jdk1.7.0\bin. Set the PATH variable as follows on Microsoft Windows:

 

• Click Start, then Control Panel, then System.
• Click Advanced, then Environment Variables.
• Add the location of the bin folder of the JDK installation for the PATH variable in System Variables. The following is a typical value for the PATH variable:

   

  C:\WINDOWS\system32;C:\WINDOWS;C:\Program Files\Java\jdk1.7.0\bin
  

Note:

• The PATH environment variable is a series of directories separated by semicolons (;) and is not case-sensitive. Microsoft Windows looks for programs in the PATH directories in order, from left to right.
• You should only have one bin directory for a JDK in the path at a time. Those following the first instance are ignored.
• If you are not sure where to add the path, add it to the right of the value of the PATH variable.
• The new path takes effect in each new command window you open after setting the PATH variable.

Source : Oracle's Documents

[MeVsYou]

Topic moved to the Programming section!

Edited August 13, 2014 by MeVsYou