code: public void setInputFormatClass(Class<? extends InputFormat> cls
                                    ) throws IllegalStateException {
      ensureState(JobState.DEFINE);
      conf.setClass(INPUT_FORMAT_CLASS_ATTR, cls, InputFormat.class);
    }
docs: Set the {@link InputFormat} for the job.
  @param cls the <code>InputFormat</code> to use
  @throws IllegalStateException if the job is submitted