Java implicit conversion of int to byte

Question

I am about to start working on something the requires reading bytes and creating strings. The bytes being read represent UTF-16 strings. So just to test things out I wante

Answer 1

If you use a number without a hint (e.g. 1234L for a long) the compiler assumes an integer. The value 0xffffffff is an integer with value -1 which can be cast to byte without a warning.

Answer 2

Because 0xffffffff is the number -1 and -1 can be interpreted as a byte.

Answer 3

0xff is the same as writing 0x000000ff, not 0xffffffff. So that's your issue; the integer is a positive number (255), but the byte (if converted bit-for-bit) would be a negative number (-1). But 0xffffffff is -1 both as an int and as a byte.

Answer 4

The key thing to remember here is that int in Java is a signed value. When you assign 0xffffffff (which is 2^32 -1), this is translated into a signed int of value -1 - an int cannot actually represent something as large as 0xffffffff as a positive number.

So for values less than 0x80 and greater than 0xFFFFFF80, the resulting int value is between -128 and 127, which can unambiguously be represented as a byte. Anything outside that range cannot be, and needs forcing with an explicit cast, losing data in the process.

Answer 5

Because int are signed and 0xffffffff represent -1, and 0xff represent an integer of value 255, which not lie into -128 (0x80) +127 (0x7f) range of a byte.