What does “|=” mean in Java?

问题:

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

回答1:

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

回答2:

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

回答3:

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 :)

回答4:

You can read Java Langauge Specification