classpath issue in hadoop java

Question

javac -classpath "/installs/hadoop-0.20.2/*.jar;/installs/hadoop-0.20.2/lib/*.jar" appClientModule/grid/comp/tools/CleanTmp.java
appClientModule/grid/comp/tools/CleanTmp.java:2: package org.apache.hadoop.fs does not exist
import org.apache.hadoop.fs.*;
^
appClientModule/grid/comp/tools/CleanTmp.java:3: package org.apache.hadoop.mapred does not exist
import org.apache.hadoop.mapred.JobConf;
                               ^
appClientModule/grid/comp/tools/CleanTmp.java:4: package org.apache.commons.logging does not exist
import org.apache.commons.logging.*;
^
appClientModule/grid/comp/tools/CleanTmp.java:5: package org.apache.commons.logging.impl does not exist
import org.apache.commons.logging.impl.Log4JLogger;
                                      ^
appClientModule/grid/comp/tools/CleanTmp.java:8: cannot find symbol
symbol  : class Log4JLogger
location: class grid.comp.tools.CleanTmp
    Log4JLogger lg=new Log4JLogger(this.getClass().getName());
    ^
appClientModule/grid/comp/tools/CleanTmp.java:9: cannot find symbol
symbol  : class JobConf
location: class grid.comp.tools.CleanTmp
    JobConf jconf;
    ^
appClientModule/grid/comp/tools/CleanTmp.java:8: cannot find symbol
symbol  : class Log4JLogger
location: class grid.comp.tools.CleanTmp
    Log4JLogger lg=new Log4JLogger(this.getClass().getName());
                       ^
7 errors
tools $ javac -classpath "/installs/hadoop-0.20.2/*.jar;/installs/hadoop-0.20.2/lib/*.jar" appClientModule/grid/comp/tools/CleanTmp.java
jabir:CompareHdfs jabir.ahmed$ javac -classpath "/installs/hadoop-0.20.2/*.jar;/installs/hadoop-0.20.2/lib/*.jar" appClientModule/grid/comp/tools/CleanTmp.java
appClientModule/grid/comp/tools/CleanTmp.java:2: package org.apache.hadoop.fs does not exist
import org.apache.hadoop.fs.*;
^
appClientModule/grid/comp/tools/CleanTmp.java:3: package org.apache.hadoop.mapred does not exist
import org.apache.hadoop.mapred.JobConf;
                               ^
appClientModule/grid/comp/tools/CleanTmp.java:4: package org.apache.commons.logging does not exist
import org.apache.commons.logging.*;
^
appClientModule/grid/comp/tools/CleanTmp.java:5: package org.apache.commons.logging.impl does not exist
import org.apache.commons.logging.impl.Log4JLogger;
                                      ^
appClientModule/grid/comp/tools/CleanTmp.java:8: cannot find symbol
symbol  : class Log4JLogger
location: class grid.comp.tools.CleanTmp
    Log4JLogger lg=new Log4JLogger(this.getClass().getName());
    ^
appClientModule/grid/comp/tools/CleanTmp.java:9: cannot find symbol
symbol  : class JobConf
location: class grid.comp.tools.CleanTmp
    JobConf jconf;
    ^
appClientModule/grid/comp/tools/CleanTmp.java:8: cannot find symbol
symbol  : class Log4JLogger
location: class grid.comp.tools.CleanTmp
    Log4JLogger lg=new Log4JLogger(this.getClass().getName());
                       ^
7 errors
tools $ ls /installs/hadoop-0.20.2/lib/*.jar
/installs/hadoop-0.20.2/lib/ant-contrib-1.0b3.jar           /installs/hadoop-0.20.2/lib/jasper-runtime-5.5.12.jar
/installs/hadoop-0.20.2/lib/aspectjrt-1.6.5.jar             /installs/hadoop-0.20.2/lib/jets3t-0.6.1.jar
/installs/hadoop-0.20.2/lib/aspectjtools-1.6.5.jar          /installs/hadoop-0.20.2/lib/jetty-6.1.26.cloudera.1.jar
/installs/hadoop-0.20.2/lib/commons-cli-1.2.jar             /installs/hadoop-0.20.2/lib/jetty-servlet-tester-6.1.26.cloudera.1.jar
/installs/hadoop-0.20.2/lib/commons-codec-1.4.jar           /installs/hadoop-0.20.2/lib/jetty-util-6.1.26.cloudera.1.jar
/installs/hadoop-0.20.2/lib/commons-daemon-1.0.1.jar            /installs/hadoop-0.20.2/lib/jsch-0.1.42.jar
/installs/hadoop-0.20.2/lib/commons-el-1.0.jar              /installs/hadoop-0.20.2/lib/junit-4.5.jar
/installs/hadoop-0.20.2/lib/commons-httpclient-3.1.jar          /installs/hadoop-0.20.2/lib/kfs-0.2.2.jar
/installs/hadoop-0.20.2/lib/commons-logging-1.0.4.jar           /installs/hadoop-0.20.2/lib/log4j-1.2.15.jar
/installs/hadoop-0.20.2/lib/commons-logging-api-1.0.4.jar       /installs/hadoop-0.20.2/lib/mockito-all-1.8.2.jar
/installs/hadoop-0.20.2/lib/commons-net-1.4.1.jar           /installs/hadoop-0.20.2/lib/oro-2.0.8.jar
/installs/hadoop-0.20.2/lib/core-3.1.1.jar              /installs/hadoop-0.20.2/lib/servlet-api-2.5-20081211.jar
/installs/hadoop-0.20.2/lib/hadoop-fairscheduler-0.20.2-cdh3u2.jar  /installs/hadoop-0.20.2/lib/servlet-api-2.5-6.1.14.jar
/installs/hadoop-0.20.2/lib/hsqldb-1.8.0.10.jar             /installs/hadoop-0.20.2/lib/slf4j-api-1.4.3.jar
/installs/hadoop-0.20.2/lib/jackson-core-asl-1.5.2.jar          /installs/hadoop-0.20.2/lib/slf4j-log4j12-1.4.3.jar
/installs/hadoop-0.20.2/lib/jackson-mapper-asl-1.5.2.jar        /installs/hadoop-0.20.2/lib/xmlenc-0.52.jar
/installs/hadoop-0.20.2/lib/jasper-compiler-5.5.12.jar## Heading ##

So how do i set the class path

I tried setting via the env variable too

$ echo $CLASSPATH /installs/hadoop/lib/.jar:/installs/hadoop/.jar:/installs/hadoop-0.20.2/.jar:/installs/hadoop-0.20.2/lib/.jar

it still fails

$ javac -version javac 1.6.0_29

Solution

Go for a more clear classpath like:

javac -classpath $HADOOP_HOME/hadoop-core-0.20.204.0.jar:$HADOOP_HOME/lib/commons-cli-1.2.jar -d inception src/Inception.java

(in this case Inception is your java program. don't know why i mentioned that but it's better to be more explicit then not!)

Most of the time you are going to need the hadoop-core-(yourversion) and the commons-cli if you are using the Tool interface.