What does "|=" mean in Java?

Question

Note my question is not regarding != but |=

A usage example is here

I assume that x |= y is the same as x = x | y but I could not find confirming documentation and wanted to be sure

Thanks

Answer 1

It's a bitwise "or" plus assignment, so you are quite correct in your assumption.

Answer 2

You can read Java Langauge Specification

Answer 3

Yes, it's a bitwise inclusive or assignment: http://www.cafeaulait.org/course/week2/03.html

Answer 4

More correctly, x |= y is actually computed as x = x | (y).

Here is an interesting example of why this is important.

int c = 2;
c %= c++ * ++c;

The interesting consequence here is that it would be written as

c = c % (c++ * ++c);

Java specifications tell us that the JVM will see the initial c first and store it, anything preceding it will have no effect on it, thus c++ & ++c will not actually affect the outcome of the calculation. It will always be c = 2 % which equals 2 :)