Could not find the main class, program will exit

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11-02-2010, 11:17 AM
grottesco

Could not find the main class, program will exit

Hi everyone, I'm new to this forum and I hope I'm writing in the right board.

I'm working on eclipse 3.5.2 on a Ubuntu VM.
I've been debugging my program for a while now and never had any problem compiling, until yesterday when after just uncommenting a line i got this error while trying to compile:

Exception in thread "main" java.lang.NoClassDefFoundError: Huffman/Main
Caused by: java.lang.ClassNotFoundException: Huffman.Main
at java.net.URLClassLoader$1.run(URLClassLoader.java: 217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 21)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 66)
Could not find the main class: Huffman.Main. Program will exit.

I undoed (oh dear.. it's a regular verb.. isn't it?) the typing thing but did anything.

Thanks a lot in advance for any help.
11-02-2010, 11:41 AM
Eranga

What's your class name and the file name that you've save as *.java ?
11-02-2010, 01:33 PM
grottesco

Quote:

Originally Posted by Eranga

What's your class name and the file name that you've save as *.java ?

It's an eleven classes project, every class has class name equal to file name.
Or maybe i misunderstood waht you were asking.. I'm pretty noob with both java and eclipse sorry =)
11-02-2010, 01:58 PM
Tolls

That's not a compile time error, that's a runtime error.
11-03-2010, 06:25 AM
Eranga

Mainly the error 'Exception in thread "main" java.lang.NoClassDefFoundError' means that the class which you are trying to run (not compile) has not found in the classpath.

To solve that problem you can add the class file into the classpath. Are you using any external jar files in your code?

Did you change anything in your classpath?
11-03-2010, 06:30 AM
Eranga

Quote:

Originally Posted by grottesco

It's an eleven classes project, every class has class name equal to file name.

Some of the compilers doing messy things with the class name and the physical file name. I might ask what's your OS with that question actually, because that messy things happen with some of the Linux version. You can compile a class with two different names. So in that case sometime the *.class file is fail to load.
11-03-2010, 06:35 AM
pbrockway2

That's a slightly nonstandard name. Make sure that you don't mean to run huffman.Main

(since you ask, no, it's irregular: "undid")
11-03-2010, 06:51 AM
Eranga

Then if something like happen, Eclipse should take the responsibility.