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From Hemanth Yamijala <yhema...@yahoo-inc.com>
Subject RE: Newbie question...with appropriate apologies in advance...
Date Fri, 27 Jul 2007 04:30:58 GMT
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/compiler/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_HOME}/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:parallelguy@yahoo.com] 
> > Sent: Thursday, July 26, 2007 3:00 PM
> > To: hadoop-user@lucene.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_HOME}/hadoop-0.13.0/src/examples/org/apache/hadoop/examples
> > % javac -classpath 
> > ${HADOOP_HOME}/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(SecureClassLoader.
> > 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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> > 
> 
> 
> 
>        
> ---------------------------------
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