code: private void printHelp() {
      String summary =
        "Usage: bin/hdfs oev [OPTIONS] -i INPUT_FILE -o OUTPUT_FILE\n" +
        "Offline edits viewer\n" +
        "Parse a Hadoop edits log file INPUT_FILE and save results\n" +
        "in OUTPUT_FILE.\n" +
        "Required command line arguments:\n" +
        "-i,--inputFile <arg>   edits file to process, xml (case\n" +
        "                       insensitive) extension means XML format,\n" +
        "                       any other filename means binary format\n" +
        "-o,--outputFile <arg>  Name of output file. If the specified\n" +
        "                       file exists, it will be overwritten,\n" +
        "                       format of the file is determined\n" +
        "                       by -p option\n" +
        "\n" + 
        "Optional command line arguments:\n" +
        "-p,--processor <arg>   Select which type of processor to apply\n" +
        "                       against image file, currently supported\n" +
        "                       processors are: binary (native binary format\n" +
        "                       that Hadoop uses), xml (default, XML\n" +
        "                       format), stats (prints statistics about\n" +
        "                       edits file)\n" +
        "-h,--help              Display usage information and exit\n" +
        "-v,--verbose           More verbose output, prints the input and\n" +
        "                       output filenames, for processors that write\n" +
        "                       to a file, also output to screen. On large\n" +
        "                       image files this will dramatically increase\n" +
        "                       processing time (default is false).\n";
  
  
      System.out.println(summary);
      System.out.println();
      ToolRunner.printGenericCommandUsage(System.out);
    }
docs: Print help.