Java Utililty Methods Convert via ByteBuffer

if (b == null)
    return "";
StringBuffer buf = new StringBuffer();
int size = b.length;
for (int i = 0; i < size; i++) {
    if ((i + 1) % 16 == 0) {
        buf.append(zeropad(Integer.toHexString(byteToUInt(b[i])).toUpperCase(), 2));
        buf.append('\n');
...

StringBuilder buf = new StringBuilder(buffer.length << 1);
for (byte b : buffer)
    addHexByte(buf, b);
return buf.toString();

hexString = hexString.replaceAll("\\W+", "");
if (hexString.length() % 2 != 0) {
    throw new RuntimeException("Input string's size must be even.");
byte[] result = new byte[hexString.length() / 2];
for (int i = 0; i < hexString.length(); i += 2) {
    result[i / 2] = (byte) Integer.valueOf(hexString.substring(i, i + 2), 16).intValue();
return ByteBuffer.wrap(result);

String decStr = "";
ByteBuffer bytes = ByteBuffer.allocate(hexStr.length() / 2);
for (int i = 0; i < hexStr.length(); i += 2) {
    Byte b = (byte) (0xff & Integer.parseInt(hexStr.substring(i, i + 2), 16));
    bytes.put(b);
bytes.position();
try {
...

byte[] asc = new byte[src.length * 2];
asc = rpBytes(src, src.length * 2, (byte) 0x00);
for (int i = 0; i < src.length; i++) {
    asc[i * 2] = bcdToByte((byte) (src[i] >> 4 & 0x0f));
    asc[i * 2 + 1] = bcdToByte((byte) (src[i] & 0x0f));
return asc;

ByteBuffer bytes = ByteBuffer.allocate(hexStr.length() / 2);
for (int i = 0; i < hexStr.length(); i += 2) {
    Byte b = (byte) (0xff & Integer.parseInt(hexStr.substring(i, i + 2), 16));
    bytes.put(b);
return bytes.array();

byte[] bytes = new BigInteger(hexString, 16).toByteArray();
if (bytes.length > 0 && bytes[0] == 0) {
    return Arrays.copyOfRange(bytes, 1, bytes.length);
} else {
    return bytes;

ImmutableList.Builder<Integer> list = ImmutableList.builder();
ByteBuffer buffer = ByteBuffer.wrap(bytes);
while (buffer.hasRemaining()) {
    list.add(buffer.getInt());
return list.build();

byte[] byteArray = new byte[intArray.length * 4]; 
ByteBuffer byteBuf = ByteBuffer.wrap(byteArray);
IntBuffer intBuff = byteBuf.asIntBuffer();
intBuff.put(intArray);
return byteArray;

ByteBuffer buffer = ByteBuffer.allocate(values.size() * Integer.BYTES);
for (int value : values) {
    buffer.putInt(value);
return buffer.array();