### Question:
ByteUtil { public static int firstNonZeroByte(byte[] data) { for (int i = 0; i < data.length; ++i) { if (data[i] != 0) { return i; } } return -1; } private  ByteUtil(); static byte[] appendByte(byte[] bytes, byte b); static byte[] cloneBytes(byte[] bytes); static byte[] bigIntegerToBytes(BigInteger b, int numBytes); static byte[] bigIntegerToBytes(BigInteger value); static byte[] parseBytes(byte[] input, int offset, int len); static int matchingNibbleLength(byte[] a, byte[] b); static byte[] longToBytes(long val); static byte[] longToBytesNoLeadZeroes(long val); static byte[] intToBytes(int val); static byte[] intToBytesNoLeadZeroes(int val); static String toHexString(byte[] data); static byte[] calcPacketLength(byte[] msg); static int byteArrayToInt(byte[] b); static long byteArrayToLong(byte[] b); static String nibblesToPrettyString(byte[] nibbles); static String oneByteToHexString(byte value); static int numBytes(String val); static int firstNonZeroByte(byte[] data); static byte[] stripLeadingZeroes(byte[] data); static boolean increment(byte[] bytes); static byte[] copyToArray(BigInteger value); static ByteArrayWrapper wrap(byte[] data); static byte[] setBit(byte[] data, int pos, int val); static int getBit(byte[] data, int pos); static byte[] and(byte[] b1, byte[] b2); static byte[] or(byte[] b1, byte[] b2); static byte[] merge(byte[]... arrays); static boolean isSingleZero(byte[] array); static boolean isAllZeroes(byte[] array); static Set<T> difference(Set<T> setA, Set<T> setB); static int length(byte[]... bytes); static short bigEndianToShort(byte[] bs); static short bigEndianToShort(byte[] bs, int off); static byte[] shortToBytes(short n); static int numberOfLeadingZeros(byte[] bytes); static byte[] leftPadBytes(@Nonnull byte[] original, int newLength); static boolean fastEquals(byte[] left, byte[] right); static final byte[] EMPTY_BYTE_ARRAY; }### Answer:
@Test public void firstNonZeroByte_1() { byte[] data = Hex.decode("0000000000000000000000000000000000000000000000000000000000000000"); int result = ByteUtil.firstNonZeroByte(data); assertEquals(-1, result); }
@Test public void firstNonZeroByte_2() { byte[] data = Hex.decode("0000000000000000000000000000000000000000000000000000000000332211"); int result = ByteUtil.firstNonZeroByte(data); assertEquals(29, result); }
@Test public void firstNonZeroByte_3() { byte[] data = Hex.decode("2211009988776655443322110099887766554433221100998877665544332211"); int result = ByteUtil.firstNonZeroByte(data); assertEquals(0, result); }