Here you can find the source of toHex(byte[] buf)
public static String toHex(byte[] buf)
//package com.java2s; public class Main { public static String toHex(String txt) { return toHex(txt.getBytes()); }// w w w.j a v a 2 s .c o m public static String toHex(byte[] buf) { if (buf == null) return ""; StringBuffer result = new StringBuffer(2 * buf.length); for (int i = 0; i < buf.length; i++) { appendHex(result, buf[i]); } return result.toString(); } private static void appendHex(StringBuffer sb, byte b) { final String HEX = "0123456789ABCDEF"; sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f)); } }