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From: Nigel Wade <nmw-news@ion.le.ac.uk>
Newsgroups: comp.lang.java.help
Subject: Re: Beginners Problem - Class Definition Not Found
Date: Fri, 22 Jul 2011 16:08:07 +0100
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On 22/07/11 15:47, William Colls wrote:
> Environment:
> Kubuntu 10.04 patched up to date 64 bit.
> java version 1.6.0_24
> Netbeans IDE 6.8
>
> I am trying to set up a connection to my google calendar, using the
> information provided at the Google API web site. I have the following
> program, which builds correctly with the Netbeans IDE 6.8
>
> If I understand the error message correctly, it is saying that it can't
> find a class definition for com.google.gdata.wireformats.AltRegistry.
> This class appears to be defined in gdata-core-1.0.jar. This file is in
> the library listing for Netbeans.
>
> At runtime, the CLASSPATH variable points to the folder that contains
> all the .jar files that are referenced by the import statements.
>
> So why doesn't the program find the class definition?
>
> // begin my program
>
> package google;
>
> import com.google.gdata.client.*;
> import com.google.gdata.client.calendar.*;
> import com.google.gdata.data.*;
> import com.google.gdata.data.acl.*;
> import com.google.gdata.data.calendar.*;
> import com.google.gdata.data.extensions.*;
> import com.google.gdata.util.*;
>
> import java.net.*;
> import java.io.*;
>
> import sample.util.*;
>
>
> public class Calender {
>
> public static void main(String[] args) {
>
> CalendarService myService = null;
> URL feedUrl = null;
> CalendarFeed resultFeed = null;
>
> try {
> myService = new CalendarService("exampleCo-exampleApp-1.0");
> myService.setUserCredentials("root@gmail.com", "pa$$word");
> }
> catch(AuthenticationException ae) {
> System.out.println("Authentication Exception: " + ae.getMessage());
> }
>
> try {
> feedUrl = new
>
> URL("http://www.google.com/calendar/feeds/default/allcalendars/full");
> resultFeed = myService.getFeed(feedUrl, CalendarFeed.class);
> }
>
> catch(MalformedURLException mue) {
> System.out.println("URL Exception: " + mue.getMessage());
> }
>
> catch(ServiceException se) {
> System.out.println("Service Exception: " + se.getMessage());
> }
> catch (java.io.IOException ioe) {
> System.out.println("IO Exception: " + ioe.getMessage());
> }
>
> System.out.println("Your calendars:");
> System.out.println();
>
> for (int i = 0; i < resultFeed.getEntries().size(); i++) {
> CalendarEntry entry = resultFeed.getEntries().get(i);
> System.out.println("\t" + entry.getTitle().getPlainText());
> }
> }
> }
>
> // end my program
>
> However when I try to run it I get the following error message:
>
> Exception in thread "main" java.lang.NoClassDefFoundError:
> com/google/common/collect/Maps
> at com.google.gdata.wireformats.AltRegistry.<init>(AltRegistry.java:118)
> at com.google.gdata.wireformats.AltRegistry.<init>(AltRegistry.java:100)
> at com.google.gdata.client.Service.<clinit>(Service.java:555)
> at google.Calender.main(Calender.java:27)
> Caused by: java.lang.ClassNotFoundException: com.google.common.collect.Maps
> at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
> ... 4 more
>
> I recognize that the credentials provided in the listing above are
> wrong. I will put the correct ones in when I get this thing to run.
>
> Thanks for your patience with a beginner in the wonderful world of java.
>

The classpath doesn't include all jar's in a directory.

Classpath defines 2 things. The root directory of a package hierarchy 
for class files, and/or a jar file. So, for class files you use a 
directory in the classpath, for a jar file you use the path of the jar 
(note, not the directory containing the jar, the actual jar file). With 
NetBeans you ought not to need to set the classpath.

How are you running your application? If you are running it within 
NetBeans then it should take care of all this for you. If you are 
running it outside of NetBeans then NetBeans should have created a dist/ 
directory containing your application jar, and a dist/lib directory 
containing each referenced jar. Each of the jar's in the dist/lib 
directory should be set in the classpath section of the jar's manifest.

-- 
Nigel Wade