Your First Java Program - Printable Version

Your First Java Program - Printable Version

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Your First Java Program - Solixious - 03-22-2013

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.

Code:
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).

[Image: Scr_2.jpg]

Step 3

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

Type in the following command

Code:
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 :

Code:
'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.

Code:
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

Code:
java HelloHC

Congratulations! You just executed your first Java Program!
Cheers Smile

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:

Code:
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:

Code:
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

RE: Your First Java Program - Deque - 03-23-2013

Thanks for this. -stickied-

I have two suggestions for improvement:

For usage of JDK as you describe it you have to update the PATH variable on Windows. That is not trivial for most people. So maybe you can add a description how to install JDK properly, how to update the environmental variable, where to get the JDK from and also one sentence what it actually is (Java Developement Toolkit).

Here is a description about updating the PATH: http://docs.oracle.com/javase/7/docs/webnotes/install/windows/jdk-installation-windows.html#path

The HelloHC.java has no indentation at all. Can you add a proper one?

RE: Your First Java Program - virusreloaded - 05-03-2013

Nice Tutorial mate... but you should show other way to create path using My Computer > Properties >Advance setting.
That's much easier to understand as many beginner find GUI comfortable as compared to CLI ..
This was just a suggestion ... Smile

RE: Your First Java Program - noize - 07-03-2013

I noticed here is not told any way to add directories to the PATH variable. This could be done from explorer.exe by following Computer -> System properties -> Advanced system settings -> Advanced -> Environmental variables, or in an easier way from cmd.exe:

Code:
set path=%path%;C:\newPathIWantToAdd\

The above command would just temporarily append a new path to the PATH variable, to save changes you should then use:

Code:
reg.exe ADD "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v Path /t REG_EXPAND_SZ /d %path% /f

RE: Your First Java Program - loserman - 07-09-2013

learning right now form college and making a good project for student feedback Biggrin

RE: Your First Java Program - Buster - 07-31-2013

I want to learn about hacking, already know basics of both Java and C. Which language would you guys prefer me to learn?

RE: Your First Java Program - Solixious - 07-31-2013

Maybe this will help you..
http://www.hackcommunity.com/Thread-Programming-language-FAQ-and-choosing-guide

RE: Your First Java Program - Buster - 07-31-2013

(07-31-2013, 02:17 PM)Solixious Wrote: Maybe this will help you..
http://www.hackcommunity.com/Thread-Programming-language-FAQ-and-choosing-guide

Ah thankyou very much, I am searching for some thing like this :epic:

RE: Your First Java Program - blackeagle - 09-24-2013

u should use netbeans for java programming if i'm not wrong it auto-compile the program u just right it and hit run we use it at university !!