Hi,
I used to get this error when using the Eclipse IDE and a
setting called
the Compiler compliance level was set to lower than Java
1.5, which does
not support generics.
Even if you are not using Eclipse, I wonder if the problem
is the same -
i.e. ant is somehow picking up an old version of the JDK.
Can you try
ensuring that it is pointing to a proper version at build
time ?
Thanks
Hemanth
On Thu, 2007-07-26 at 19:11 -0700, C G wrote:
> Vivek and everyone: Thanks for the info. I am just
trying to build the examples as a cheap proxy for how to
write my own code.
>
> I tried your suggestion, the result was 125 errors
and a slew of warnings, here's one for example:
>
> [javac] 1. ERROR in
/home/CG/hadoop-0.13.0/src/java/org/apache/hadoop/record/com
piler/CGenerator.java (at line 42
> )
> [javac] void genCode(String name,
ArrayList<JFile> ilist,
> [javac] ^^^^^^^^^
> [javac] The type ArrayList is not generic; it
cannot be parameterized with arguments <JFile>
>
> Clearly there is something environmental I am doing
wrong. I followed the configuration instructions in the
getting started guide, and it all worked from the
perspective of being able to run things out of the box.
>
> Is there a guide or FAQ discussing building and
deploying that I missed?
>
> Any advice greatly appreciated. The map/reduce
paradigm is super cool and I can't wait to get past these
operational issues and start laying down some code.
>
> Thanks!
> CG
>
> Vivek Ratan <vivekr yahoo-inc.com> wrote:
> NOt sure if I understand what you're trying to do.
But,
> - if you're modiying one of the examples and want to
compile the modified
> code, run 'ant examples' under
$/hadoop-0.13.0. (I assume
> you're familiar with 'ant'). This will recreate the
examples jar file (under
> the build directory), which you can copy over the
existing one. This is the
> easiest way to compile your code as the root build.xml,
which ant uses, sets
> up all the right classpaths and other things for
compilation.
> - if you're creating examples of your own, you'll
probably need to add your
> class to org.apache.hadoop.example.ExampleDriver and
then run ant.
>
>
> > -----Original Message-----
> > From: C G [mailto:parallelguyyahoo.com]
> > Sent: Thursday, July 26, 2007 3:00 PM
> > To: hadoop-userlucene.apache.org
> > Subject: Newbie question...with appropriate
apologies in advance...
> >
> > I've deployed hadoop-0.13.0 and successfully run
some
> > examples. Now I am trying to compile and run the
examples
> > prior to starting to develop my own code. I've
managed to do
> > little more than get a nice spew of error
messages. This is
> > no doubt due to my own ignorance and too much
Python
> > programming, but can anybody tell me how to
compile the
> > examples (WordCount.java for example) and run
them?
> >
> > I apologize for the basic question, which I am
sure is
> > classpath-magic related. Any assistance most
appreciated. I
> > promise to be helpful to other newbs like myself
going forward.
> >
> > I've tried a bunch of stuff, but it all comes down
to
> > various "can't find class X' errors. This is
representative
> > of as far as I've gotten:
> > % java -version
> > java version "1.6.0_02"
> > Java(TM) SE Runtime Environment (build
1.6.0_02-b05) Java
> > HotSpot(TM) Client VM (build 1.6.0_02-b05, mixed
mode, sharing
> > % cd
> >
$/hadoop-0.13.0/src/examples/org/apache/hadoop/
examples
> > % javac -classpath
> >
$/hadoop-0.13.0/hadoop-0.13.0-core.jar
WordCount.java
> > % jar -cvf WordCount.jar *.class
> > % cp *.jar ${HADOOP_HOME/hadoop-0.13.0/
> > % cd ${HADOOP_HOME/hadoop-0.13.0/
> > % bin/hadoop jar WordCount.jar WordCount
> > input_files/text.txt output_files/results2.txt
Exception in
> > thread "main"
java.lang.NoClassDefFoundError: WordCount
> > (wrong name:
org/apache/hadoop/examples/WordCount)
> > at java.lang.ClassLoader.defineClass1(Native
Method)
> > at
java.lang.ClassLoader.defineClass(ClassLoader.java:620)
> > at
> >
java.security.SecureClassLoader.defineClass(SecureClassLoade
r.
> > java:124)
> > at
> >
java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
> > at
java.net.URLClassLoader.access$000(URLClassLoader.java:56)
> > at
java.net.URLClassLoader$1.run(URLClassLoader.java:195)
> > at
java.security.AccessController.doPrivileged(Native Method)
> > at
java.net.URLClassLoader.findClass(URLClassLoader.java:188)
> > at
java.lang.ClassLoader.loadClass(ClassLoader.java:306)
> > at
java.lang.ClassLoader.loadClass(ClassLoader.java:251)
> > at
> >
java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319
)
> > at java.lang.Class.forName0(Native Method)
> > at java.lang.Class.forName(Class.java:247)
> > at
org.apache.hadoop.util.RunJar.main(RunJar.java:148)
> >
> >
> >
> > ---------------------------------
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