Hi All,
I installed Hadoop 1.0.4 on Cygwin and tried to run Java HelloWorld but I get exception error:

$ bin/hadoop javac HelloWorld.java
java.lang.NoClassDefFoundError: javac
Exception in thread "main"

$ echo $JAVA_HOME
/cygdrive/c/java
$ javac HelloWorld.java
$ java HelloWorld
Hello, World
I have set JAVA_HOME environment variable in hadoop-env.sh .
How do I make it work on hadoop?
Thank you.

Hadoop is not a java runtime environment it runs special map/reduce applications.  Go search for "how to write a hadoop program" and there will be lots of examples or you can pick up a book on Hadoop and that can help you with some examples too.

--Bobby

From: R J <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Reply-To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>, R J <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Date: Wednesday, November 14, 2012 3:00 PM
To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Subject: Hadoop Java compilation error

Hi All,
I installed Hadoop 1.0.4 on Cygwin and tried to run Java HelloWorld but I get exception error:
$ bin/hadoop javac HelloWorld.java
java.lang.NoClassDefFoundError: javac
Exception in thread "main"
$ echo $JAVA_HOME
/cygdrive/c/java
$ javac HelloWorld.java
$ java HelloWorld
Hello, World
I have set JAVA_HOME environment variable in hadoop-env.sh .
How do I make it work on hadoop?
Thank you.

Thanks a lot.

I studied and tried the WordCount.java program as in the URL http://hadoop.apache.org/docs/r0.20.2/mapred_tutorial.html

$ javac -version
javac 1.6.0
$javac -classpath /usr/local/hadoop-1.0.4/hadoop-core-1.0.4.jar:/usr/local/hadoop-1.0.4/lib/commons-cli-1.2.jar -d wordcount_classes WordCount.java
I get 48 compilation errors. The first few are like:
WordCount.java:6: package org.apache.hadoop.fs does not exist
        import org.apache.hadoop.fs.Path;
WordCount.java:7: package org.apache.hadoop.conf does not exist
        import org.apache.hadoop.conf.*;
It seems the javac compiler cannot locate the hadoop packages. Is there any other way to include the packages in the compilation command? Thank you.

 

________________________________
 From: Robert Evans <[EMAIL PROTECTED]>
To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>; R J <[EMAIL PROTECTED]>
Sent: Wednesday, November 14, 2012 3:36 PM
Subject: Re: Hadoop Java compilation error
 

Hadoop is not a java runtime environment it runs special map/reduce applications.  Go search for "how to write a hadoop program" and there will be lots of examples or you can pick up a book on Hadoop and that can help you with some examples too.

--Bobby
From:  R J <[EMAIL PROTECTED]>
Reply-To:  "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>, R J <[EMAIL PROTECTED]>
Date:  Wednesday, November 14, 2012 3:00 PM
To:  "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
Subject:  Hadoop Java compilation error
Hi All,
I installed Hadoop 1.0.4 on Cygwin and tried to run Java HelloWorld but I get exception error:

$ bin/hadoop javac HelloWorld.java
java.lang.NoClassDefFoundError: javac
Exception in thread "main"

$ echo $JAVA_HOME
/cygdrive/c/java
$ javac HelloWorld.java
$ java HelloWorld
Hello, World
I have set JAVA_HOME environment variable in hadoop-env.sh .
How do I make it work on hadoop?
Thank you.

Hi

You are seeing these compilation errors because some hadoop jars are absent in your classpath.

You need to add the required jars from HADOOP_HOME and HADOOP_HOME/lib in your class path.

Easier approach would be to build and pack your application jar in an IDE like eclipse , deploy the jar on your hadoop client machine and run it using 'hadoop jar ...' command.

Regards
Bejoy KS

Sent from handheld, please excuse typos.

-----Original Message-----
From: R J <[EMAIL PROTECTED]>
Date: Wed, 14 Nov 2012 15:21:39
To: Robert Evans<[EMAIL PROTECTED]>; [EMAIL PROTECTED]<[EMAIL PROTECTED]>
Reply-To: [EMAIL PROTECTED]
Subject: Re: Hadoop Java compilation error

Thanks a lot.

I studied and tried the WordCount.java program as in the URL http://hadoop.apache.org/docs/r0.20.2/mapred_tutorial.html

$ javac -version
javac 1.6.0
$javac -classpath /usr/local/hadoop-1.0.4/hadoop-core-1.0.4.jar:/usr/local/hadoop-1.0.4/lib/commons-cli-1.2.jar -d wordcount_classes WordCount.java
I get 48 compilation errors. The first few are like:
WordCount.java:6: package org.apache.hadoop.fs does not exist
        import org.apache.hadoop.fs.Path;
WordCount.java:7: package org.apache.hadoop.conf does not exist
        import org.apache.hadoop.conf.*;
It seems the javac compiler cannot locate the hadoop packages. Is there any other way to include the packages in the compilation command? Thank you.

 

________________________________
 From: Robert Evans <[EMAIL PROTECTED]>
To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>; R J <[EMAIL PROTECTED]>
Sent: Wednesday, November 14, 2012 3:36 PM
Subject: Re: Hadoop Java compilation error
 

Hadoop is not a java runtime environment it runs special map/reduce applications.  Go search for "how to write a hadoop program" and there will be lots of examples or you can pick up a book on Hadoop and that can help you with some examples too.

--Bobby
From:  R J <[EMAIL PROTECTED]>
Reply-To:  "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>, R J <[EMAIL PROTECTED]>
Date:  Wednesday, November 14, 2012 3:00 PM
To:  "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
Subject:  Hadoop Java compilation error
Hi All,
I installed Hadoop 1.0.4 on Cygwin and tried to run Java HelloWorld but I get exception error:

$ bin/hadoop javac HelloWorld.java
java.lang.NoClassDefFoundError: javac
Exception in thread "main"

$ echo $JAVA_HOME
/cygdrive/c/java
$ javac HelloWorld.java
$ java HelloWorld
Hello, World
I have set JAVA_HOME environment variable in hadoop-env.sh .
How do I make it work on hadoop?
Thank you.

In order to run Hadoop program you will need it run it as follows:

$hadoop jar <jar-name>.jar <class-name>

Where:
class-name is comiled .class file with main() method
name-jar is a jar containing .class files

Compile your HelloWorld.java into HelloWorld.class. Create a jar file from HelloWorld.class and call it , say HW.jar

Then execute the program as follows:
$hadoop jar HW.jar HelloWorld

Happy Hadooping,
AK7

From: Robert Evans [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, November 14, 2012 4:37 PM
To: [EMAIL PROTECTED]; R J
Subject: Re: Hadoop Java compilation error

Hadoop is not a java runtime environment it runs special map/reduce applications.  Go search for "how to write a hadoop program" and there will be lots of examples or you can pick up a book on Hadoop and that can help you with some examples too.

--Bobby

From: R J <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Reply-To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>, R J <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Date: Wednesday, November 14, 2012 3:00 PM
To: "[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>" <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>>
Subject: Hadoop Java compilation error

Hi All,
I installed Hadoop 1.0.4 on Cygwin and tried to run Java HelloWorld but I get exception error:
$ bin/hadoop javac HelloWorld.java
java.lang.NoClassDefFoundError: javac
Exception in thread "main"
$ echo $JAVA_HOME
/cygdrive/c/java
$ javac HelloWorld.java
$ java HelloWorld
Hello, World
I have set JAVA_HOME environment variable in hadoop-env.sh .
How do I make it work on hadoop?
Thank you.
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