Exception error

lewright · July 13th, 2006, 12:42 PM

Whenever I try to run any of the examples in the book I get the following error:

C:\>java c:\java\programs\mathcalc
Exception in thread "main" java.lang.NoClassDefFoundError: c:\java\programs\mathcalc

I thought it might have something to do with the CLASSPATH but I have tried every classpath I can think of and still have the problem.

jetbrains · July 13th, 2006, 08:43 PM

Please make sure the class name is same as the java file name.

See below tutorial about how to write and compile first java class
http://www.developerzone.biz/index.p...=128&Itemid=36

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http://www.javawisdom.com/
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lewright · July 14th, 2006, 03:39 PM

Quote:

quote:Originally posted by lewright
Whenever I try to run any of the examples in the book I get the following error:

C:\>java c:\java\programs\mathcalc
Exception in thread "main" java.lang.NoClassDefFoundError: c:\java\programs\mathcalc

I thought it might have something to do with the CLASSPATH but I have tried every classpath I can think of and still have the problem.

The Class and Java files have the same name.
Also, I can not see any thing wrong with programs, and here is one for example:

public class MathCalc
{
  public static void main (String[] args)
  {
    // Calculate the radius of a circle
    // which has an area of 100 square feet
    double radius = 0.0;
    double circleArea = 100.0;
    int feet = 0;
    int inches = 0;
    radius = Math.sqrt(circleArea/Math.PI);
    feet = (int)Math.floor(radius); // Get the whole feet and nothing but the

feet
    inches = (int)Math.round(12.0*(radius - feet));
    System.out.println("The radius of a circle with area " + circleArea +
                      " square feet is\n " + feet + " feet " + inches + "

inches");
  }
}

This thing is driving me nuts.

panacea · July 14th, 2006, 07:22 PM

Have you compiled the .java into a .class file yet? To do this, use the "javac" command, not "java". Once you have a .class file you can run "java mathcalc".

Jon Emerson
http://www.devexplore.com/developer/...jects.php?id=6

lewright · July 15th, 2006, 03:20 PM

Quote:

quote:Originally posted by panacea
Have you compiled the .java into a .class file yet? To do this, use the "javac" command, not "java". Once you have a .class file you can run "java mathcalc".

Jon Emerson
http://www.jonemerson.net/

Yes I have made the class file via the java command.

panacea · July 16th, 2006, 03:16 PM

Ah, ok. Try running the "java" command from the folder that contains mathcalc.exe. For example:

C:\>cd java\programs
C:\java\programs\>java mathcalc

Jon Emerson
http://www.devexplore.com/developer/...jects.php?id=6

lewright · July 17th, 2006, 08:28 AM

Quote:

quote:Originally posted by panacea
Ah, ok. Try running the "java" command from the folder that contains mathcalc.exe. For example:

C:\>cd java\programs
C:\java\programs\>java mathcalc

Jon Emerson
http://www.devexplore.com/developer/...jects.php?id=6

I just did what you suggested and from what I got below I think I had better reload my JAVA software.

C:\>cd java\programs

C:\Java\Programs>java mathcalc
Exception in thread "main" java.lang.UnsupportedClassVersionError: mathcalc (Unsupported major.minor version 49.0)
        at java.lang.ClassLoader.defineClass0(Native Method)
        at java.lang.ClassLoader.defineClass(Unknown Source)
        at java.security.SecureClassLoader.defineClass(Unknow n Source)
        at java.net.URLClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.access$100(Unknown Source)
        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)

Thanks

lewright · July 17th, 2006, 03:51 PM

Quote:

quote:Originally posted by lewright

Quote:

quote:Originally posted by panacea

Quote:

Ah, ok. Try running the "java" command from the folder that contains mathcalc.exe. For example:

C:\>cd java\programs
C:\java\programs\>java mathcalc

Jon Emerson
http://www.devexplore.com/developer/...jects.php?id=6

I just did what you suggested and from what I got below I think I had better reload my JAVA software.

C:\>cd java\programs

C:\Java\Programs>java mathcalc
Exception in thread "main" java.lang.UnsupportedClassVersionError: mathcalc (Unsupported major.minor version 49.0)
        at java.lang.ClassLoader.defineClass0(Native Method)
        at java.lang.ClassLoader.defineClass(Unknown Source)
        at java.security.SecureClassLoader.defineClass(Unknow n Source)
        at java.net.URLClassLoader.defineClass(Unknown Source)
        at java.net.URLClassLoader.access$100(Unknown Source)
        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)

Thanks

I reloaded the software and did what you last recommended and everything worked perfect. Thanks a lot for your suggestion.

Lee Wright

panacea · July 17th, 2006, 06:35 PM

No problem :). It seems like you were compiling your .java file with JDK 1.5, but then running it with JRE 1.4. In the future you probably don't need to reinstall Java -- just change your system PATH so that it points to the right runtime environment :).

Jon Emerson
http://www.jonemerson.net/