// onjava/Hex.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// {java onjava.Hex}
package onjava;
import java.io.*;
import java.nio.file.*;

public class Hex {
  public static String format(byte[] data) {
    StringBuilder result = new StringBuilder();
    int n = 0;
    for(byte b : data) {
      if(n % 16 == 0)
        result.append(String.format("%05X: ", n));
      result.append(String.format("%02X ", b));
      n++;
      if(n % 16 == 0) result.append("\n");
    }
    result.append("\n");
    return result.toString();
  }
  public static void
  main(String[] args) throws Exception {
    if(args.length == 0)
      // Test by displaying this class file:
      System.out.println(format(
        Files.readAllBytes(Paths.get(
          "build/classes/main/onjava/Hex.class"))));
    else
      System.out.println(format(
        Files.readAllBytes(Paths.get(args[0]))));
  }
}
/* Output: (First 6 Lines)
00000: CA FE BA BE 00 00 00 34 00 61 0A 00 05 00 31 07
00010: 00 32 0A 00 02 00 31 08 00 33 07 00 34 0A 00 35
00020: 00 36 0A 00 0F 00 37 0A 00 02 00 38 08 00 39 0A
00030: 00 3A 00 3B 08 00 3C 0A 00 02 00 3D 09 00 3E 00
00040: 3F 08 00 40 07 00 41 0A 00 42 00 43 0A 00 44 00
00050: 45 0A 00 14 00 46 0A 00 47 00 48 07 00 49 01 00
                  ...
*/