Why i don't get an error?

Question

In Java if I do the following I get an error

byte b = 50;
b = b * 2; // Error! Cannot assign an int to a byte!

Ok I understood why I got that error . But now if I do b*=2 I don't get any error. Why?

I'm assuming because b*=2 is automatically casting the result back as a byte, you could do `b = (byte) (b * 2);` — mike, Mar 28 '17 at 12:45
Just in case: although the question was closed, you could still consider accepting one of the answers ... or go forward and delete the question altogether. Your choice. — GhostCat, Mar 28 '17 at 13:53

score 1 · Accepted Answer · answered Mar 28 '17 at 12:48

1

Because when you make b *= 2; in fact this operation *= will cast your int to byte.

answered Mar 28 '17 at 12:48

YCF_L

GhostCat · Answer 2 · 2017-03-28T12:52:11.773

0

The reason is simply because there are different rules for narrowing conversions for = and *=.

See here for details on widening in general; and then you go here to understand the difference for those *= operations.

You, see

b *= 2

works out as

b = (byte) ( (b) * 2 )

and that narrowing conversion doesn't play a role here.

edited Mar 28 '17 at 12:52

answered Mar 28 '17 at 12:45

GhostCat

2 Answers2