为什么使用UTF-16编码会得到一个奇怪的字节序列？

Question

byte[] byt = "君".getBytes(StandardCharsets.UTF_8);
for (byte b : byt) {
    System.out.println(Integer.toBinaryString(b));
}

Output:

11111111111111111111111111100101
11111111111111111111111110010000
11111111111111111111111110011011

This is right.

But:

byte[] byt = "君".getBytes(StandardCharsets.UTF_16);
for (byte b : byt) {
    System.out.println(Integer.toBinaryString(b));
}

Output:

11111111111111111111111111111110
11111111111111111111111111111111
1010100
11011

君's hexadecimal code is 101010000011011

So:

11111111111111111111111111111110
11111111111111111111111111111111

What is this?

Answer 1

The first to bytes 0xFEFF or

11111111111111111111111111111110
11111111111111111111111111111111

are Byte Order Mark - they tell if the rest is encoded using Big Endian or Little Endian.

If you don't wan't them you can set the encoding explicitly - use StandardCharsets.UTF_16LE or StandardCharsets.UTF_16BE