//  Examine.java  Copyright (c) 2006 Kari Laitinen

//  http://www.naturalprogramming.com

//  2006-02-22   File created.
//  2006-02-22   Last modification.

//  The best way to execute this program is to run it in a
//  command prompt window where command line parameters can
//  be given. It may be difficult, and even impossible, to
//  supply the command line parameters if this program is 
//  executed with a modern development tool such as JCreator
//  or Eclipse.

//  A solution to Exercise 14-8.

import java.util.Scanner ;
import java.io.* ;    // Classes for file handling.


class Examine
{
   public static void main( String[] command_line_parameters )
   {
      Scanner keyboard  =  new  Scanner( System.in ) ;

      if ( command_line_parameters.length  ==  1 )
      {
         try
         {
            FileInputStream file_to_read  =
                       new FileInputStream( command_line_parameters[ 0 ] ) ;

            byte[]  bytes_from_file  =  new  byte[ 16 ] ;

            int lines_printed_since_last_pause  =  0 ;

            int number_of_bytes_read  ;

            while (( number_of_bytes_read  =
                       file_to_read.read( bytes_from_file ))  >  0 )
            {
               StringBuilder  line_of_bytes  =  new  StringBuilder() ;
               StringBuilder  bytes_as_characters  =  new  StringBuilder () ;

               for ( int byte_index  =  0 ;
                         byte_index  <  number_of_bytes_read ;
                         byte_index  ++ )
               {
                  line_of_bytes.append(
                    String.format( " %02X", bytes_from_file[ byte_index ] ) ) ;

                  char  byte_as_character  =
                                  (char) bytes_from_file[ byte_index ] ;

                  if ( byte_as_character  >=  ' ' )
                  {
                     bytes_as_characters.append( byte_as_character ) ;
                  }
                  else
                  {
                     bytes_as_characters.append( ' ' ) ;
                  }
               }

               System.out.printf( "\n%-48s  %s", line_of_bytes,
                                                 bytes_as_characters ) ;

               lines_printed_since_last_pause  ++  ;

               if ( lines_printed_since_last_pause  >  22 )
               {
                  System.out.print( "\n Press the Enter key to continue ..." ) ;
                  String any_string_from_keyboard  =  keyboard.nextLine() ;
                  lines_printed_since_last_pause  =  0 ;
               }
            }

            file_to_read.close() ;
         }
         catch ( FileNotFoundException  caught_file_not_found_exception )
         {
            System.out.print( "\n Cannot open file "
                           +  command_line_parameters[ 0 ] ) ;
         }
         catch ( IOException  caught_io_exception )
         {
            System.out.print( "\n Error while processing file "
                           +  command_line_parameters[ 0 ] ) ;
         }
      }
      else
      {
         System.out.print( "\n You have to command this program as: \n"
                        +  "\n  java Examine file.ext \n") ;
      }
   }
}