The compiler seems to be ok with this (single digit hex values only):
byte[] rawbytes={0xa, 0x2, 0xf};
But not this:
byte[]
As the other answered already said, byte is a signed type in Java. The range is from -128 to 127 inclusive. So 0xff is equal to -0x01. You can use 0xff instead of -0x01 if you add a manual cast:
byte[] rawbytes={0xa, 0x2, (byte) 0xff};