If I don't synchronize this method I'll get wrong values?

Question

public static int getCRC16(byte[] bytes) {
    CRC16 crc = new CRC16();
    crc.reset();
    crc.update(bytes, 0, bytes.length);
    return (int) crc.getValue();
}

Tons of threads will hit this method, if I don't synchronize I'll get a wrong crc for a specific thread?

Answer 1

This is a static method. Usually you need to worry about thread safety when you're dealing with the state of an object. For example, if you were changing values inside the CRC16 class itself, but you're not. Your function just takes an input bytes and returns an output crc.getValue().

Answer 2

No, it is fine, as long as you don't use any shared variables. The bytesand crcare local per thread. That's why they are called local variables.

Answer 3

Extending the other answers, threads do not extend the Java language regarding visibility and scopes, only regarding the mode of execution of code, which means that values that only a single object can access or which are only valid locally are not needed to synchronize - only if values are being shared between multiple objects (static fields of a class, or a singleton instance where all accessors are getting returned the same object) synchronization gets worthy philosophizing about.