code: public static void setInputPathFilter(Job job,
                                          Class<? extends PathFilter> filter) {
      job.getConfiguration().setClass("mapred.input.pathFilter.class", filter, 
                                      PathFilter.class);
    }
docs: Set a PathFilter to be applied to the input paths for the map-reduce job.
  @param job the job to modify
  @param filter the PathFilter class use for filtering the input paths.