### Question:
ObjectId implements Comparable<ObjectId>, Serializable { public int byteN(int index) { int b = this.hashCode[index] & 0xFF; return b; } ObjectId();  ObjectId(byte[] raw); private  ObjectId(byte[] raw, boolean cloneArg); static ObjectId createNoClone(byte[] rawHash); boolean isNull(); @Override boolean equals(Object o); @Override int hashCode(); @Override String toString(); static ObjectId valueOf(final String hash); static byte[] toRaw(final String hash); int compareTo(final ObjectId o); static int compare(byte[] left, byte[] right); byte[] getRawValue(); void getRawValue(byte[] target); void getRawValue(byte[] target, int size); static ObjectId forString(final String strToHash); int byteN(int index); static final Ordering<ObjectId> NATURAL_ORDER; static final ObjectId NULL; static final HashFunction HASH_FUNCTION; static final int NUM_BYTES; }### Answer:
@Test public void testByeN() { ObjectId oid = new ObjectId(new byte[] { 00, 01, 02, 03, (byte) 0xff, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }); assertEquals(0, oid.byteN(0)); assertEquals(1, oid.byteN(1)); assertEquals(2, oid.byteN(2)); assertEquals(3, oid.byteN(3)); assertEquals(255, oid.byteN(4)); }