What are the order of operations when using two assignment operators in a single line?
public static void main(String[] args){
int i = 0;
int[] a = {3, 6};
a[i] = i = 9; // this line in particular
System.out.println(i + " " + a[0] + " " + a[1]);
}
I get that = takes values from the right, but when I compile this I get:
9 9 6
I thought it would have been and ArrayOutOfBounds exception, but it is assigning 'a[i]' before it's moving over the 9. Does it just do that for arrays?
=
is parsed as right-associative, but order of evaluation is left-to-right.
So: The statement is parsed as a[i] = (i = 9)
. However, the expression i
in a[i]
is evaluated before the right hand side (i = 9
), when i
is still 0
.
It's the equivalent of something like:
int[] #0 = a;
int #1 = i;
int #2 = 9;
i = #2;
#0[#1] = #2;