Question

In the following code I have an error
“possible loss of precision
found : int
required: short”.
I understand what the error means but I’m just wondering why I’m getting it. Surely the function should return a type of short (I can’t see how there could be any loss of precision, the code should return a 16 bit integer). Can anyone clear up for me why the following code seems to require the type int?

static short a() {
    short[] payload = {
            100, 200, 300,
            400, 500, 600,
            700, 800, 900, 1000
    };
    short offset = 2;
    return (payload[offset - 2] << 8 & 0xff00) + (payload[offset - 1] & 0xff);
}

Thanks!

Answer 1

Java arithmetic operations on short always return int, partly to help prevent overflow, and partly to reflect the underlying JVM bytecode, which doesn’t distinguish between arithmetic operations on int, short, or byte. But basically, (payload[offset - 2] << 8 & 0xff00) is an int, and it wants you to cast it back down to a short.