Error Messages...

[Aaron Woodland]

I feel like I have no clue what I am doing! I just installed what I think is the Java server for programming in Java, but I don't know if I have or not. It made its own enviromental variable on my computer :

C:\Sun\AppServer\bin;C:\j2sdk1.4.2_08\bin

I run the compiler and it works, but whenever I run it it does not work and I always have to put C where the file is located at) after java in DOS prompt. I thought you could just write

javac HelloWorld.java

...

I am also getting this error message when I run it correctly for example

java C:\Java\HelloWorld or HelloWorld.java

The error is:

Exception in thread "main" java.lang.NoClassDefFoundError C:\Java\HelloWorld.java

Can anyone tell me the reason behind this?
Rat

[Jim Yingst]

"Raistin", welcome to JavaRanch. It looks like you may have overlooked our display name policy when you signed up. Your name falls in the category of "obviously fictitious"; please change it. Thank you.

[Aaron Woodland]

Okay, name changed...

[Jim Yingst]

Thanks. It sounds like you need to set the classpath, either by setting the system variable CLASSPATH or by using the -classpath flag (which can be shortened to -cp):

java -cp . HelloWorld

The dot means that the classpath is set to the current directory, the some one that HelloWorld.java and HelloWorld.class are in.

[Aaron Woodland]

Hi,
I did as you said and set a class path variable for the two directories...

C:\Java
C:\Documents and Settings\Kevin\My Documents\Java Programs
I am still getting the same error message though.

[Marilyn de Queiroz]

You also need to make sure that the PATH includes the path to javac.exe (probably something like
PATH=C:\j2sdk1.4.2_08\bin;%PATH%
Then, as long as you are sitting in the same directory as the source file (for example the file is here:
C:\java\SourceFile.java
and you are here:
C:\Java>),
you can just type
javac SourceFile.java
otherwise you need to type
javac C:\(full path to the source file)\SourceFile.java
[ August 09, 2005: Message edited by: Marilyn de Queiroz ]

[Jim Yingst]

It sounds like the javac step is working, and calling java you're at least getting a NoClassDefinitionFoundError. That tells us that the system is able to find the javac.exe and java.exe files in the PATH.

So, your source file is apparently at

    C:\Java\HelloWorld.java

correct? After you compile with javac, is there a .class file at

    C:\Java\HelloWorld.class ?

If not, where is it? What directory are you actually in?

Note also that when you try to run with java, you do not include the .java or .class extension to the filename. Just include the name of the class.

If none of the above helps, then I would guess that the CLASSPATH is still wrong. What, exactly, is it set to? You can get this info on Windows with

    echo %CLASSPATH%

[Rick O'Shay]

IMO the short cuts and use of CLASSPATH do nothing but confuse the new user.

Forget about packages and third-party jars and start with a basic Hello.java that outputs Hello.class and you want to run that.

First type in foobar and hit enter. That's what you will see if either java or javac is not installed or not in your path. I assume they are because it is automatically done by the installer.

Now, tell the compiler where to put the output as follows. We will use spaces in path names requiring quotes.

javac -d "/some folder/some where" Hello.java

OK, now let's run it and tell java where the class can be found:

java -classpath "/some folder/some where" Hello

In this case "class" is assumed.

Here's a more complicated example where the source file is not in the current directory:

javac -d "/some folder/some where" "/acme/rocket engines/Hello.java"

Javac doesn't care where the source is, 'long as you tell it. You know where the class is because you specified it explicitly.

[Aaron Woodland]

Here is what shows up in the Enviromental variables under PATH:

C:\Sun\AppServer\bin;C:\j2sdk1.4.2_08\bin

Here is what is under CLASSPATH:

C:\Java,C:\Documents and Settings\Kevin\My Documents\Java Programs

After I did compile my HelloWorld program I did get a .CLASS file in the directory where I kept my source file which is located at C:\Java... It is still getting the same error after I have ran the program even after making sure everything is correct... I also feel like I have a ton of Java stuff installed also...

Raistlin

[Kristin Stromberg]

You are so close! Just turn that comma in your classpath (right after C:\Java) into a semi-colon and you should be good to go.

As an aside, you don't need Sun's app server unless you want to develop and test JSPs, Servlets, EJB's etc. For the "regular stuff", the JDK is all you need (the stuff that's in the C:\j2sdk1.4.2_08\bin).

[Aaron Woodland]

After adding the semi colon between C:\Java,C:\Documents and Settings\Kevin\My Documents\Java Programsand getting rid of C:\Sun\AppServer\bin, so it wil show this:

PATH:
C:\j2sdk1.4.2_08\bin

CLASSPATH:
C:\Java;C:\Documents and Settings\Kevin\My Documents\Java Programs

After inserting in the following:

javac HelloWorld.java

It still has an error message which is :

error: cannot read: HelloWorld.java
1 error

After compiling it like I used to do which is :

javac C:\Java\HelloWorld.java

It compiles the .java file after inserting this code into it.

After compiling it I type in

java C:Java\HelloWorld (and have tryed HelloWorld.java and .class)  

I get the same error message as before...

Exception in thread "main" java.lang.NoClassDefFoundError

C:\Java\HelloWorld.java

Might I also include I have the compiler Netbeans, Jcreator, and Eclipse... I also have the folowing Java files:
j2sdk-1_4_2_08-windows-i586-p
j2eesdk-1_4_01_2005Q1-windows
jdk-1_5_0_04-windows-i586-p
and probably a few others....

Might I also add that the code I am compiling is just the simple HelloWorld application:

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

Raistlin
[ August 10, 2005: Message edited by: Aaron Woodland ]

[Joanne Neal]

Originally posted by Aaron Woodland:

After compiling it I type in

java C:Java\HelloWorld (and have tryed HelloWorld.java and .class)  

Almost there, try just

java HelloWorld

[Marilyn de Queiroz]

C:\Java>javac HelloWorld.java

C:\Java>javac C:\Java\HelloWorld.java

C:\Java>java HelloWorld

C:\Java>java C:Java\HelloWorld

Just wanted to verify that you are sitting in the C:\Java directory while you're typing all these commands.
[ August 10, 2005: Message edited by: Marilyn de Queiroz ]

[Kristin Stromberg]

Hmmm. After you changed your classpath, did you open a new command window to run your java stuff? If so and it's still not working, try adding "." to your classpath (without the quotes, and preceded by a semi-colon).

[Joanne Neal]

Originally posted by Marilyn de Queiroz:
Just wanted to verify that you are sitting in the C:\Java directory while you're typing all these commands.

[ August 10, 2005: Message edited by: Marilyn de Queiroz ][/QB]

Shouldn't matter as c:\java is (assuming nothing has changed from earlier posts) in his classpath

[Marilyn de Queiroz]

Originally posted by Joanne Neal:
Shouldn't matter as c:\java is (assuming nothing has changed from earlier posts) in his classpath

Have you tried it?

C:\Program Files\Java\jdk1.5.0_03\bin>echo %classpath%
C:\Java;.;C:\tinkering\jr.jar;C:\j2sdkee1.3.1\lib\j2ee.jar;C:\apache-ant-1.6.1\lib\ant.jar;C:\junit3.8.1\junit.jar

C:\Program Files\Java\jdk1.5.0_03\bin>javac Dog.java
error: cannot read: Dog.java
1 error

C:\Program Files\Java\jdk1.5.0_03\bin>javac C:\Java\Dog.java

C:\Program Files\Java\jdk1.5.0_03\bin>
[ August 10, 2005: Message edited by: Marilyn de Queiroz ]

[Jean-Sebastien Abella]

when you run java you dont put the .java or .class at the end of the class... just the name of the Class...

[Rick O'Shay]

After you changed your classpath, did you open a new command window to run your java stuff

Alternatively he could not ignore the best practice of not using CLASSPATH as shown in my example. Funny thing is that had the procedure I outlined been followed none of these issues would still be present and he would have a general solution to compiling and running anything from anywhere. Oh well, no way like the hard way I suppose.

[Marilyn de Queiroz]

Originally posted by Rick O'Shay:
Funny thing is that had the procedure I outlined been followed none of these issues would still be present and he would have a general solution to compiling and running anything from anywhere.

Not true, Rick.

C:\Program Files\Java\jdk1.5.0_03\bin>javac -d C:\Java Dog.java
error: cannot read: Dog.java
1 error

But:
C:\Program Files\Java\jdk1.5.0_03\bin>javac -d C:\Java C:\Java\Dog.java
works.

Also,
C:\Java>javac Dog.java
works just fine
[ August 10, 2005: Message edited by: Marilyn de Queiroz ]

[Aaron Woodland]

I am so confused... lol I am pretty new at DOS prompt also... So what do I need to do to run the program?
Rat

[Matt Fielder]

Holy crap. No offence, but this is supposed to be easier? He's obviously learning and you're throwing a whole mess of crap at him.

What happened to going to:

set the path (directions at sun's site)
open notepad and write code
open command prompt
navigate to the folder you have your .java file in that you just wrote ( cd c:\javastuff )
compile: javac filename.java
run: java filename

the guy's trying to do HelloWorld. Why the hell would he confuse life with a CLASSPATH?

(just reread that. didn't mean to sound like an ass. it just came out that way)

[Marilyn de Queiroz]

What happened to going to:

set the path (directions at sun's site)

Seems like his path is good. (seems like his classpath is good now too)

open notepad and write code

Seems like his code is good.

open command prompt
navigate to the folder you have your .java file in that you just wrote ( cd c:\javastuff )

This is what I keep asking. Haven't got an answer yet.

compile: javac filename.java
run: java filename

Yep.
[ August 10, 2005: Message edited by: Marilyn de Queiroz ]

[Aaron Woodland]

LoL... Thanks for the information Fielder. I got the program running.
Rat

[Joanne Neal]

Originally posted by Marilyn de Queiroz:
Originally posted by Joanne Neal:
Shouldn't matter as c:\java is (assuming nothing has changed from earlier posts) in his classpath

Have you tried it?

I agree it won't work for compiling, but it was running the program that the OP was having problems with and

java HelloWorld

will work from any directory if c:\java is in the classpath. I guess I should have made it clearer that that was what I was referring to.

[Marilyn de Queiroz]

Originally posted by Aaron Woodland:
LoL... Thanks for the information Fielder. I got the program running.
Rat

I'm glad to hear that.

[Aaron Woodland]

I just want to thanks for everyone elses help to. I actually had no clue about this website till I started reading "Head First Java"!
Thanks,
Rat