Java Utililty Methods ID Value Create

byte[] bytes = new byte[20]; 
new Random().nextBytes(bytes);
char[] charMapping = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p' };
char[] chars = new char[40];
for (int i = 0; i < bytes.length; i++) {
    int left = (bytes[i] >> 4) & 0x0f;
    int right = bytes[i] & 0x0f;
    chars[i * 2] = charMapping[left];
...

byte[] bytes = new byte[20]; 
random.nextBytes(bytes);
char[] chars = new char[40];
for (int i = 0; i < bytes.length; i++) {
    int left = (bytes[i] >> 4) & 0x0f;
    int right = bytes[i] & 0x0f;
    chars[i * 2] = charMapping[left];
    chars[i * 2 + 1] = charMapping[right];
...

long seed1 = System.currentTimeMillis();
while (seed1 == seed)
    seed1 = System.currentTimeMillis(); 
seed = seed1;
Random r = new Random(seed);
return Integer.toString(r.nextInt(), 16) + "-" + Integer.toString(r.nextInt(65535), 16) + "-"
        + Integer.toString(r.nextInt(65535), 16) + "-" + Integer.toString(r.nextInt(65535), 16);

Random rand = new Random();
int id = rand.nextInt(989) + 1;
while (id > 497 && id < 651) {
    id = rand.nextInt(989) + 1;
return id;

int id = 1000000 + rng.nextInt(8999999);
String sid = String.valueOf(id);
return ("id" + sid);

byte[] id = new byte[RANDOM_ID_LENGTH];
new Random().nextBytes(id);
return id;

final long autoGeneratredID = new DateTime().getMillis();
final String concate = message + Long.toString(autoGeneratredID);
return bytesToHex(messageDigest.digest(concate.getBytes()));

Random rand = new Random(seed);
int id = rand.nextInt();
if (id > 0) {
    id = -id;
return id;

java.security.MessageDigest md;
String pwd = null;
try {
    md = MessageDigest.getInstance("MD5");
    byte[] b = origin.getBytes("UTF-8");
    byte[] hash = md.digest(b);
    String str = byteArrayToHexString(hash);
    return str;
...

return generateId(salt, "MD5");