// onjava/Hex.java
// (c)2016 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
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("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 53 0A 00 05 00 22 07
00010: 00 23 0A 00 02 00 22 08 00 24 07 00 25 0A 00 26
00020: 00 27 0A 00 28 00 29 0A 00 02 00 2A 08 00 2B 0A
00030: 00 2C 00 2D 08 00 2E 0A 00 02 00 2F 09 00 30 00
00040: 31 08 00 32 0A 00 33 00 34 0A 00 15 00 35 0A 00
00050: 36 00 37 07 00 38 0A 00 12 00 39 0A 00 33 00 3A
                  ...
*/