title: incompatibility of hadoop versions
body: <p>I've developed a MapReduce with reduce-side join on Hadoop 0.20.2 version. All java classes compiles without any error. My program works as it has to. But this version of hadoop is on test virtual machine.
  On my real cluster I have another version of hadoop (hadoop 2.00-cdh4.1.2). When I want to compile java-classes it doesn't work. I get 100 errors like following:</p>
  
  <pre><code>JoinMapper.java:8: package org.apache.hadoop.filecache does not exist
  import org.apache.hadoop.filecache.DistributedCache;
                                    ^
  JoinMapper.java:9: package org.apache.hadoop.fs does not exist
  import org.apache.hadoop.fs.Path;
                             ^
  JoinMapper.java:10: package org.apache.hadoop.io does not exist
  import org.apache.hadoop.io.Text;
                             ^
  JoinMapper.java:11: package org.apache.hadoop.io does not exist
  import org.apache.hadoop.io.*;
  ^
  JoinMapper.java:12: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.FileInputFormat;
                                 ^
  JoinMapper.java:13: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.FileOutputFormat;
                                 ^
  JoinMapper.java:14: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.InputFormat;
                                 ^
  JoinMapper.java:15: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.JobClient;
                                 ^
  JoinMapper.java:16: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.JobConf;
                                 ^
  JoinMapper.java:17: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.MapReduceBase;
                                 ^
  JoinMapper.java:18: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.Mapper;
                                 ^
  JoinMapper.java:19: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.OutputCollector;
                                 ^
  JoinMapper.java:20: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.Reporter;
                                 ^
  JoinMapper.java:21: package org.apache.hadoop.mapred does not exist
  import org.apache.hadoop.mapred.TextOutputFormat;
                                 ^
  JoinMapper.java:22: package org.apache.hadoop.mapreduce.lib.input does not exist
  import org.apache.hadoop.mapreduce.lib.input.MultipleInputs;
                                              ^
  JoinMapper.java:23: package org.apache.hadoop.util does not exist
  import org.apache.hadoop.util.Tool;
                               ^
  JoinMapper.java:24: package org.apache.hadoop.util does not exist
  import org.apache.hadoop.util.ToolRunner;
                               ^
  JoinMapper.java:26: cannot find symbol
  symbol: class MapReduceBase
  public class JoinMapper extends MapReduceBase implements Mapper&lt;LongWritable, Text, TextPair, Text&gt; {
                                  ^
  JoinMapper.java:26: cannot find symbol
  symbol: class Mapper
  public class JoinMapper extends MapReduceBase implements Mapper&lt;LongWritable, Text, TextPair, Text&gt; {
                                                           ^
  JoinMapper.java:26: cannot find symbol
  symbol: class LongWritable
  public class JoinMapper extends MapReduceBase implements Mapper&lt;LongWritable, Text, TextPair, Text&gt; {
                                                                  ^
  JoinMapper.java:26: cannot find symbol
  symbol: class Text
  public class JoinMapper extends MapReduceBase implements Mapper&lt;LongWritable, Text, TextPair, Text&gt; {
                                                                                ^
  TextPair.java:2: package org.apache.hadoop.io does not exist
  import org.apache.hadoop.io.*;
  ^
  TextPair.java:4: cannot find symbol
  symbol: class WritableComparable
  public class TextPair implements WritableComparable&lt;TextPair&gt; {
                                   ^
  TextPair.java:4: interface expected here
  public class TextPair implements WritableComparable&lt;TextPair&gt; {
                                                     ^
  JoinMapper.java:26: cannot find symbol
  symbol: class Text
  public class JoinMapper extends MapReduceBase implements Mapper&lt;LongWritable, Text, TextPair, Text&gt; {
                                                                                                ^
  JoinMapper.java:26: interface expected here
  public class JoinMapper extends MapReduceBase implements Mapper&lt;LongWritable, Text, TextPair, Text&gt; {
                                                                 ^
  NcdcRecordParser.java:2: package org.apache.hadoop.io does not exist
  import org.apache.hadoop.io.*;   
  </code></pre>
  
  <p>I understand this version doesn't have packages that I need. But I don't know how to solve my problem. Can anyone help me?</p>