设置classpath后，包org.apache.hadoop.conf不存在

Question

I am a beginner in hadoop using the hadoop's beginners guide book as a tutorial.

I am using a mac osx 10.9.2 and hadoop version 1.2.1

I have set all the appropriate class path, when I call echo $PATH in terminal:

Here is the result I get:

/Library/Frameworks/Python.framework/Versions/2.7/bin:/Users/oladotunopasina/hadoop-1.2.1/hadoop-core-1.2.1.jar:/Users/oladotunopasina/hadoop-1.2.1/bin:/usr/share/grails/bin:/usr/share/groovy/bin:/Users/oladotunopasina/.rvm/gems/ruby-2.1.1/bin:/Users/oladotunopasina/.rvm/gems/ruby-2.1.1@global/bin:/Users/oladotunopasina/.rvm/rubies/ruby-2.1.1/bin:/usr/local/heroku/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/Users/oladotunopasina/.rvm/bin:/Users/oladotunopasina/.rvm/bin

I tried compiling WordCount1.java and I am getting the following error:

WordCount1.java:2: package org.apache.hadoop.conf does not exist
import org.apache.hadoop.conf.Configuration ;
                         ^
WordCount1.java:3: package org.apache.hadoop.fs does not exist
import org.apache.hadoop.fs.Path;
                       ^
WordCount1.java:4: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.IntWritable;
                       ^
WordCount1.java:5: package org.apache.hadoop.io does not exist
import org.apache.hadoop.io.Text;
                       ^
WordCount1.java:6: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Job;
                              ^
WordCount1.java:7: package org.apache.hadoop.mapreduce does not exist
import org.apache.hadoop.mapreduce.Mapper;
                              ^

Kindly help.

Answer 1

The CLASSPATH variable is the way to tell applications, including the JDK tools(javac), where to look for user classes.

You can set this variable as given below and try compiling the class.

export CLASSPATH=$CLASSPATH:/Users/oladotunopasina/hadoop-1.2.1/hadoop-core-1.2.1.jar

Answer 2

If you are using a build tools such as Maven, Gradle, sbt, etc.

You have to add the dependency plugin to your build file.

For Maven,per example, you have to add the following into your pom.xml

<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-core</artifactId>
    <version>1.2.1</version>
</dependency>

You can find the dependency settings for other build tools here