Compiling and running a java program in command prompt

Question

I have written a simple hello world program given below

package helloworld;

public class helloWorld 
{
    public static void main(String[] args)
    {
        System.out.println("Hello, World!");
    }
}

I'm using Windows 7 and have set my CLASSPATH and PATH variables in the environment variables window as

C:\Program Files\Java\jdk1.6.0_24\bin;

The program is located at

C:\Users\Admin\Documents\NetBeansProjects\javaAssignment\src\helloWorld

So, basically when i try to run it in my command prompt, the following happens

C:\Users\Admin\Documents\NetBeansProjects\javaAssignment\src\helloWorld>javachelloWorld.java

C:\Users\Admin\Documents\NetBeansProjects\javaAssignment\src\helloWorld>java helloWorld
Exception in thread "main" java.lang.NoClassDefFoundError: helloWorld (wrong name: helloworld/helloWorld)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: helloWorld.  Program will exit.

The program seems to be compiling fine and does not throw any errors. But when i try to run it, it says than exceptions have occurred. I tried looking up on Google thinking that setting my PATH and CLASSPATH was wrong, but I don't seem to find any issues with that.

have you defined any package ?

Kakarot
– Kakarot

2014-02-27 04:46:34 +00:00
Commented Feb 27, 2014 at 4:46 — Kakarot
– Kakarot, Commented Feb 27, 2014 at 4:46
@Kakarot Yes I have. Sorry, Edited the question now.

woodhead92
– woodhead92

2014-02-27 04:48:30 +00:00
Commented Feb 27, 2014 at 4:48 — woodhead92
– woodhead92, Commented Feb 27, 2014 at 4:48

Kakarot · Accepted Answer · 2014-02-27 05:08:37Z

2

In case your helloWorld.java file is in a package, you can run as follows :

C:\Users\Admin\Documents\NetBeansProjects\javaAssignment\src\
java packageName.helloWorld

Run the code from outside the helloworld package directory i.e from src directory (C:\Users\Admin\Documents\NetBeansProjects\javaAssignment\src)

Also check if the name of your java file is the same as your class name (helloWorld.java)

Also it seems that the name of your package is helloworld (all in small letters) however the folder name is helloWorld (note that W is capital) both the names need to match.

edited Feb 27, 2014 at 5:08

answered Feb 27, 2014 at 4:49

Kakarot

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9 Comments

woodhead92 Over a year ago

Thank you. I just tried it out. But the same exceptions are being thrown by it

Kakarot Over a year ago

try running the code from inside helloworld package directory

Kakarot Over a year ago

Check the name of the java file is it same as class file ?

woodhead92 Over a year ago

Yes, both are named helloWorld. Both helloWorld.java and helloWorld.class exist in C:\Users\Admin\Documents\NetBeansProjects\javaAssignment\src\helloWorld

Kakarot Over a year ago

did you try running the code from helloWorld folder or src folder

|

Brian · Accepted Answer · 2014-02-27 04:51:07Z

0

You need to make sure you are in the directory containing your helloWorld.class file when you issue the command

java helloWorld

answered Feb 27, 2014 at 4:51

Brian

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3 Comments

woodhead92 Over a year ago

Yeah, I reset my CLASSPATH to the director where my helloWorld.class exists. Tried running it again. Still throwing the same exceptions.

Brian Over a year ago

I mean using cd and cd.. in the command prompt. Navigate to the directory that is holding your helloWorld.class file before issuing the java command

woodhead92 Over a year ago

The helloWorld.class file has been created in the same folder on compilation C:\Users\Admin\Documents\NetBeansProjects\javaAssignment\src\helloWorld So, I dont need to change the directory, right?

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