why cannot compiler ?

[Carson Liao]

I try to recompiler WordCount.java file in the same directory as
WordCount.class
but it doesn't works !
report said something wrong with path, but I cannot figure out

       conf.setOutputKeyClass(org/apache/hadoop/io/Text);
       conf.setOutputValueClass(org/apache/hadoop/io/IntWritable);
       conf.setMapperClass(org/apache/hadoop/examples/WordCount$MapClass);
       conf.setCombinerClass(org/apache/hadoop/examples/WordCount$Reduce);
       conf.setReducerClass(org/apache/hadoop/examples/WordCount$Reduce);

really need help!!!
thx