Problem with Java in XP
I have run JDK on my Laptop with Win98 before, but that was a year or two ago. So I figured I wouldn't have any problem in XP.
So I installed the JDK 1.5.0 (which is actually 5.0 or something like that). No problems. Nice. Go to compile and run a sample program, to make sure it works. Doesn't find JAVAC.
Ok, I recognize this, have to set my PATH variable. No big deal. Add the line "C:\Program Files\Java\jdk1.5.0\bin;" ... Done. Finds and runs the Javac. Again, nice.
GO to run the program (from the command line). java SampleFile ... get this error...
Exception in thread "main" java.lang.NoClassDefFoundError: SAmpleFile
Ok, WOW, almost forgot, need to set the CLASSPATH... so I add the line "C:\Program Files\Java\jdk1.5.0\bin;" to the CLASSPATH... still get the same error.
What am I doing wrong?
You shouldn't be setting the classpath. By default it already contains the current directory.
Did you
1. Open a console window?
2. Change to the directory where the class file is?
3. Verify the class file actually does exist?
4. Use a package in the java file - which means you must use the package and appropriate directory from the command line?
5. Verify that you are typing the same name, including case, that the class is named?
Did you
1. Open a console window?
2. Change to the directory where the class file is?
3. Verify the class file actually does exist?
4. Use a package in the java file - which means you must use the package and appropriate directory from the command line?
5. Verify that you are typing the same name, including case, that the class is named?
1. Running from "command" in Windows
2. Havent changed any class locations
3. No... all it is is a simple JOptionPane dialog window
4. ?
5. As far as I know
Ok, well, run from NetBeans it works fine... but run on the command line, it gives that error. Any reason why?
> Ok, well, run from NetBeans it works fine... but run
> on the command line, it gives that error. Any reason
> why?
It's just a simple classpath issue, pure and simple.
When you run it from NetBeans, it is setting the classpath (not the CLASSPATH environment variable -- get rid of that, if you haven't already!) for you depending on how you set up the project in NetBeans.
When you run it yourself from the "java" command-line executable, you need to tell it the classpath. If you don't set a CLASSPATH environment variable, and don't pass a -classpath command-line option, then it defaults the classpath to include the current directory. Otherwise, you need to tell it.
java -classpath . YourMainClassHere
> It's just a simple classpath issue, pure and simple.... or, you specified the wrong class name.
This netbeans is a little confusing...
If I run the class directly in the java\jdk1.5.0 folder, it runs, but as soon as I move it anywhere from there, it fails. Of course, if I move it from the java\jdk1.5.0 folder, netbeans changes the code and adds a "package ClassName" in the begining of the class. Then it works, but if I comment that out, it fails.
I thought that by setting the PATH and CLASSPATH variables, I would be able to run a class from any folder I choose to save a class at?
I just want to be able to save a class I am working on in any directory and be able to run it. I swear I was able to do that on my laptop, but then again, I don't remember how I set it up on that.
> This netbeans is a little confusing...
>
> If I run the class directly in the java\jdk1.5.0
> folder, it runs, but as soon as I move it anywhere
> from there, it fails. Of course, if I move it from
> the java\jdk1.5.0 folder, netbeans changes the code
> and adds a "package ClassName" in the begining of the
> class. Then it works, but if I comment that out, it
> fails.
>
With a package, as I referred to before, the name becomes MyPackage.ClassName rather than just ClassName.
You might want to also check the version of java that you are running with the following command....
java -version
Additionally try the following command....
java -cp "<Full directory to class>" ClassName
> I thought that by setting the PATH and CLASSPATH
> variables, I would be able to run a class from any
> folder I choose to save a class at?
>
The path is necessary for java, not your class, to run correctly.
And as pointed out if you did not set the classpath correctly then you will get the error that you are seeing.
Also search your hard drive and verify that only one .class file exists for your class.
> I just want to be able to save a class I am working
> on in any directory and be able to run it. I swear I
> was able to do that on my laptop, but then again, I
> don't remember how I set it up on that.
The following information would help.
- If there is a package name what is it?
- What is the name of the class?
- What is the full path of the location of the class file?
- What does your CLASSPATH look like?
- What command exactly (the whole line) are you using to run it?
I will get that info, but also someone told me my problem is I have DreamWeaver and Photoshop on my PC. What am I supposed to do about that?
Discard it, as it has nothing to do with your problem.
Oops, "Discard" should be "Disregard".
I didn't think that would be a problem either. But you never know when it comes to computers, so thought I would ask.Thanks to everyone for the help! I have been really busy and will get on top of answering those questions ASAP.
The problem is you are being careless. so slow down. Answer these questions:
1) what is the path to your class file
2) what does the package line at the top of the source say (if you have one)
3) When you open your command window, in what directory are you [what does the command prompt say]?
If, mentally, you combine what the command prompt says, to whatever, if anything, your package says, Then it should be the full path to where the class file is.
Then you just got to make sure you have the right capitalization and spelling of the class file. Remember the name of the class, includes any package you may have specified.
I just downloaded and installed Java/NetBeans on my new Windows XP platform and I'm having the same problem. Because it's been at least 10 years since I've done any programming, I want to work from the command line for a while before tackling an IDE.
It took a while for me to figure out how to set the PATH for javac in Control Panel/System/Environment Variables instead of Autoexec.bat, but it finally seems to compile ok. But when I try to execute the .class file I get the following:
C:\PROGRA~1\JAVA\FOWGRE\BEGINNER\FOWGRE01>java fowgre01
Exception in thread "main" java.lang.NoClassDefFoundError: fowgre01 (wrong name: Java/fowgre/beginner/fowgre01)
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass1(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
etc...
The fowgre01.java and fowgre01.class files are both in the directory named C:\PROGRA~1\JAVA\FOWGRE\BEGINNER\FOWGRE01 and that's where I am when I compile and try to execute them.
Here's the source:
package Java.fowgre.beginner;
class fowgre01
{
public static void main(String[] args)
{
// let's print a simple message to the screen
System.out.println("This is my very first Java program");
}
}
I've tried modifying the first line but it's the same result:
package fowgre.beginner;
package beginner;
The compiler objects when I try to specify the full path:
package C:\Progra~1\Java.fowgre.beginner;
package C:\Program Files\Java.fowgre.beginner;
package %rootdir%\Progra~1\Java.fowgre.beginner;
etc...
I tried modifying the first line so it's simply a class instead of a package, same result ;(
I tried adding the "." symbol for current directory in the CLASSPATH variable, tried adding the full path enclosed in quotes (and without the quotes), and I tried deleting the CLASSPATH variable altogether. Still the same result.
Heeeeelllllllllllllppppppppppppppppp.
OldPoppa - if you want better attention to your problem, it would be wise to start your own topic rather than jump on the tail end of someone else's basically "closed" one.
Sorry... why? It's exactly the same problem, isn't it? Why create a new thread for the same topic?And was it resolved for the previous questioner? That's not at all clear to me.
> Sorry... why? It's exactly the same problem, isn't
> it? Why create a new thread for the same topic?
It is related perhaps, but nevertheless, you should create your own topic. Why? Even if it is still "open", put yourself in the original author's shoes. How would you feel if you were trying to get a resolution to your problem, and other people hijacked your topic basically saying "Hey, pay attention to me here instead. I'm more important than that other guy" and we end up with a scattering of replies to each other's problems, your replies buried deep in with all the others?
Seems like a rude thing to me.
And trust me, I know what I'm talking about. If you want to get more visibility to your issue, start your own topic. It's for your own good.
> Sorry... why? It's exactly the same problem, isn't
> it? Why create a new thread for the same topic?
No it isn't the same problem.
Your problem is simpler and exists solely because you are not using the fully qualified name of the class and the error message specifically tells you that.
LOL, I didn't think this was closed.
> 1) what is the path to your class file
> 2) what does the package line at the top of the
> source say (if you have one)
> 3) When you open your command window, in what
> directory are you [what does the command prompt
> say]?
1. The PATH of the class file is C:\Program Files\Java\jdk1.5.0
2. There is no package as long as I keep the class files in that PATH
3. C:\Docume~1\Defsta~1 (it is going to the Documents and Settings for the user).
All I would like to be able to do is create a folder in the JAVA path to keep my programs in, seperate from everything else. Maybe even a folder for each program, for organizational purposes.
I remember being able to do this on my 98 machine. Now I can java and javac, but when I java in prompt or try to use NetBeans on a class outside the Java\jdk 1.5.0 folder, I get the exception main error.
BTW, NetBeans keeps saying it can't find the javadoc program.When I am typing something like:JOptionPane.whateverWhen it comes up with a list of options, under each option, it says something about it can't find the javadoc.Not sure if this is related.
> > 1) what is the path to your class file
> > 2) what does the package line at the top of the
> > source say (if you have one)
> > 3) When you open your command window, in what
> > directory are you [what does the command prompt
> > say]?
>
> 1. The PATH of the class file is C:\Program
> Files\Java\jdk1.5.0
> 2. There is no package as long as I keep the class
> files in that PATH
You need to seperate your problem domains.
- Console
- IDE.
You are using an IDE.
Stop doing that until you figure out how java, the path, and the classpath interact from a console.
- The path must point to your executables (nothing to do with class files.)
- The classpath must point to the root of directory with the fully qualified class name. With no package that means the directory where the class file is.
Once the above is set then you can run the class from a console window.
And ONLY once the above works do you then start trying to get it to "work" in the IDE. The IDE does the same thing but it hides it from you (which is why it adds the package.) You need to learn what the IDE does, including options that you set via the toolbar, to understand what it is doing.
> BTW, NetBeans keeps saying it can't find the javadoc
> program.
>
> When I am typing something like:
>
> JOptionPane.whatever
>
> When it comes up with a list of options, under each
> option, it says something about it can't find the
> javadoc.
>
> Not sure if this is related.
No it's not - this is because you haven't set the IDE's option that indicates where to find the Java API documentation (if you downloaded and installed it) in your machine. Use NB's help and search on "javadoc" for instructions on setting this. You must download and install the API first for it to work.
I have no classpath environment variable defined. My path environment variable contains C:\Program Files\Java\jdk1.5.0_04\bin among other things. There is no other environment variable set on my system having anything to do with Java.
I just wrote a short program for a guy, and I tested your issue by doing the following:
Changed to the directory containing my source code. This directory has no relation to Java - that is, it's not a project directory, within the jdk structure...nothing.
I successfully compiled and ran the simple file with:
javac SortDemo.java
java SortDemo
...from the directory as described above. If it matters, it was something like C:\skydiver.
I next tried the same thing with another, slightly more complex program which has import statements. Also worked fine.
I'm a noob at Java, and I've discovered situations where Java says it can't find something though I believe it exists where it should be; that is not to say the error messages are wrong, but interpreting the reason requires an understanding of all the reasons why Java may not be able to "find" something.
I'm sorry I don't know the cause of your problem, but I do not believe it has anything to do with classpath.
It's a mistake to put your code in jdk's bin. Continuing to do so, just delays your understanding of how things work. All folks have initial problems with classpath issues, but really, it's very simple once you get it.
> > > 1) what is the path to your class file
> > > 2) what does the package line at the top of the
> > > source say (if you have one)
> > > 3) When you open your command window, in what
> > > directory are you [what does the command prompt
> > > say]?
> >
> > 1. The PATH of the class file is C:\Program
> > Files\Java\jdk1.5.0
> > 2. There is no package as long as I keep the class
> > files in that PATH
>
> You need to seperate your problem domains.
> - Console
> - IDE.
>
> You are using an IDE.
>
> Stop doing that until you figure out how java, the
> path, and the classpath interact from a console.
> - The path must point to your executables (nothing to
> do with class files.)
> - The classpath must point to the root of directory
> with the fully qualified class name. With no package
> that means the directory where the class file is.
>
> Once the above is set then you can run the class from
> a console window.
>
> And ONLY once the above works do you then start
> trying to get it to "work" in the IDE. The IDE does
> the same thing but it hides it from you (which is why
> it adds the package.) You need to learn what the IDE
> does, including options that you set via the toolbar,
> to understand what it is doing.
Ok, then I suppose I should start from the beginning, right?
I'll reset my classpath variable in the enviroments, and go from there.
I never used a IDE when I was using Win98, and I think I had a batch script whenever I was going to code java on my 98 machine.
