奇怪的Java行为

Question

Can anyone explain me this

int i=2;
int j=+-i;//-+i; 

the value of j=-2 in either case of +-i or -+i .

Is this fine in Java ? or should this be a compiler error?

Thankx in advance.

Answer 1

It's fine - you've just got two unary operators together. So it's either:

int j = +(-i);

or

int j = -(+i);

See sections 15.15.3 and 15.15.4 of the JLS for these two operators.

Answer 2

This is absolutely fine. Go through the Unary Operators in java

Both the cases are similar, the ultimate result stays same with the same operations performed in different order!!

Answer 3

just think of it this way: int j = +i would correspond to int j = i . Therefore, -+i or +-i would be -i .

Answer 4

You're applying two unary operators to i :

int j = +-i;

is equivalent to

int j = +(-i);

and similarly for -+i . The outcome is the same as negating i unless i is equal to Integer.MIN_VALUE (in which case j ends up equal to i ).