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Exception in thread "main" java.lang.NoClassDefFoundError:

 
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DarkArchon



Joined: 23 Sep 2009
Posts: 2
PostPosted: Wed Sep 23, 2009 7:10 am    Post subject: Exception in thread "main" java.lang.NoClassDefFoundError: Reply with quote
First off, system specs...
WIndows XP SP 2, NetBeans 6.7.1, java version "1.5.0_16"

And here's my code

Code:
/*
 * HelloWorldApp.java
 *
 * Created on February 5, 2006, 6:43 PM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package helloworldapp;

/**
 * The HelloWorldApp class implements an application that
 * simply prints "Hello World!" to standard output.
 */
public class HelloWorldApp {

    /** Creates a new instance of HelloWorldApp */
    public HelloWorldApp() {
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        System.out.println("Hello World!"); // Display the string.
    }

}


Simple hello world program. I compile and run it in NetBeans and everything seems to come out correctly. I see Hello World! and all. Then I try to run "java HelloWorldApp" on HelloWorldApp.class and I get a mess of error code (I'll quote it in a second). So I thought maybe I was doing something wrong. So I did the manual method. I put in ":\Sun\SDK\jdk\bin\javac HelloWorldApp.java" created a new .class and tried to run that one, got the same error. I can't figure out what I'm doing wrong.

So far I've tried
java HelloWorldApp
Java -cp . HelloWorldApp
java -classpath . helloworld
javaw HelloWorldApp

None of it seems to work. This is of course I'm running it all in the directory that my .java and .class are in "C:\Java\Hello World App\src\helloworldapp" to be exact.

Here is the error


Quote:
java HelloWorldApp
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorldApp
Caused by: java.lang.ClassNotFoundException: HelloWorldApp
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: HelloWorldApp. Program will exit.


Any ideas?
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Arshad Noor
Posted via mailing list.
PostPosted: Wed Sep 23, 2009 4:35 pm    Post subject: Exception in thread "main" java.lang.NoClassDefFoundError: Reply with quote
You have it in the "helloworldapp" package; you can only access
the class as follows:

java helloworldapp.HelloWorldApp

Arshad Noor
StrongAuth, Inc.


DarkArchon wrote:
Quote:
First off, system specs...

WIndows XP SP 2, NetBeans 6.7.1, java version "1.5.0_16"



And here's my code




Code:
/*

* HelloWorldApp.java

*

* Created on February 5, 2006, 6:43 PM

*

* To change this template, choose Tools | Template Manager

* and open the template in the editor.

*/



package helloworldapp;



/**

* The HelloWorldApp class implements an application that

* simply prints "Hello World!" to standard output.

*/

public class HelloWorldApp {



/** Creates a new instance of HelloWorldApp */

public HelloWorldApp() {

}



/**

* @param args the command line arguments

*/

public static void main(String[] args) {

System.out.println("Hello World!"); // Display the string.

}



}







Simple hello world program. I compile and run it in NetBeans and everything seems to come out correctly. I see Hello World! and all. Then I try to run "java HelloWorldApp" on HelloWorldApp.class and I get a mess of error code (I'll quote it in a second). So I thought maybe I was doing something wrong. So I did the manual method. I put in ":\Sun\SDK\jdk\bin\javac HelloWorldApp.java" created a new .class and tried to run that one, got the same error. I can't figure out what I'm doing wrong.



So far I've tried

java HelloWorldApp

Java -cp . HelloWorldApp

java -classpath . helloworld

javaw HelloWorldApp



None of it seems to work. This is of course I'm running it all in the directory that my .java and .class are in "C:\Java\Hello World App\src\helloworldapp" to be exact.



Here is the error






Quote:
java HelloWorldApp

Quote:
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorldApp

Quote:
Caused by: java.lang.ClassNotFoundException: HelloWorldApp

Quote:
at java.net.URLClassLoader$1.run(Unknown Source)

Quote:
at java.security.AccessController.doPrivileged(Native Method)

Quote:
at java.net.URLClassLoader.findClass(Unknown Source)

Quote:
at java.lang.ClassLoader.loadClass(Unknown Source)

Quote:
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)

Quote:
at java.lang.ClassLoader.loadClass(Unknown Source)

Quote:
at java.lang.ClassLoader.loadClassInternal(Unknown Source)

Quote:
Could not find the main class: HelloWorldApp. Program will exit.




Any ideas?



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DarkArchon



Joined: 23 Sep 2009
Posts: 2
PostPosted: Thu Sep 24, 2009 8:21 pm    Post subject: Reply with quote
tried java helloworldapp.HelloWorldApp Still having problems.....

Quote:


Directory of C:\Java\Hello World App\build\classes\helloworldapp

09/22/2009 11:13 PM <DIR> .
09/22/2009 11:13 PM <DIR> ..
09/22/2009 11:13 PM 575 HelloWorldApp.class
1 File(s) 575 bytes
2 Dir(s) 60,953,214,976 bytes free

C:\Java\Hello World App\build\classes\helloworldapp>java helloworldapp.HelloWorl
dApp
Exception in thread "main" java.lang.NoClassDefFoundError: helloworldapp/HelloWo
rldApp
Caused by: java.lang.ClassNotFoundException: helloworldapp.HelloWorldApp
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: helloworldapp.HelloWorldApp. Program will exit.

C:\Java\Hello World App\build\classes\helloworldapp>java -classpath . helloworld
app.HelloWorldApp
Exception in thread "main" java.lang.NoClassDefFoundError: helloworldapp/HelloWo
rldApp
Caused by: java.lang.ClassNotFoundException: helloworldapp.HelloWorldApp
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: helloworldapp.HelloWorldApp. Program will exit.

C:\Java\Hello World App\build\classes\helloworldapp>
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Arshad Noor
Posted via mailing list.
PostPosted: Thu Sep 24, 2009 8:34 pm    Post subject: Exception in thread "main" java.lang.NoClassDefFoundError: Reply with quote
You have to be in the classes directory when you execute this -
not in the helloworldapp directory.

Package-names are treated like directories. Every component of
a package-name is a sub-directory. To find a class within a
package the CLASSPATH must be at the root of the sub-directory
where the package name begins. For example if your package-name
is com.strongauth.strongkey.app, and this project is in a folder
called /usr/local/strongkey, then when you try to execute some
class - say Main.class - in that package, you have to execute
java from /usr/local/strongkey as follows:

java com.strongauth.strongkey.app.Main

or you can be anywhere and execute:

java -cp /usr/local/strongkey com.strongauth.strongkey.app.Main

Arshad Noor
StrongAuth, Inc.

DarkArchon wrote:
Quote:
tried java helloworldapp.HelloWorldApp Still having problems.....


Quote:
Directory of C:\Java\Hello World App\build\classes\helloworldapp


Quote:
09/22/2009 11:13 PM <DIR> .

Quote:
09/22/2009 11:13 PM <DIR> ..

Quote:
09/22/2009 11:13 PM 575 HelloWorldApp.class

Quote:
1 File(s) 575 bytes

Quote:
2 Dir(s) 60,953,214,976 bytes free


Quote:
C:\Java\Hello World App\build\classes\helloworldapp>java helloworldapp.HelloWorl

Quote:
dApp
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stefanimw



Joined: 29 Nov 2010
Posts: 2
PostPosted: Mon Nov 29, 2010 11:44 pm    Post subject: Exception in thread "main" java.lang.NoClassDefFoundError: Reply with quote
Arshad Noor, thank you so much! I ran into the same problem as DarkArchon and your suggestion works!
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stefanimw



Joined: 29 Nov 2010
Posts: 2
PostPosted: Mon Nov 29, 2010 11:45 pm    Post subject: Exception in thread "main" java.lang.NoClassDefFoundError: Reply with quote
Arshad Noor, thank you so much! I ran into the same problem as DarkArchon and your suggestion works!
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defrancr



Joined: 11 Mar 2013
Posts: 1
PostPosted: Mon Mar 11, 2013 11:25 am    Post subject: Reply with quote
Thank you, this little "detail" made me mad a whole weekend.
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