JAVA += OPERATOR

ezra heywood

Total Post:145

Points:1019
Posted by  ezra heywood
Java 
 781  View(s)
Ratings:
Rate this:
Until today I thought that for example:

i += j;
is just a shortcut for:

i = i + j;
But what if we try this:

int i = 5;
long j = 8;
Then i = i + j; will not compile but i += j; will compile fine.

Does it mean that in fact i += j; is a shortcut for something like this i = (type of i) (i + j)?

I've tried googling for it but couldn't find anything relevant.
  1. Mayank Tripathi

    Post:397

    Points:3117
    Re: Java = operator

    As always with these questions, the JLS holds the answer. In this case §15.26.2 Compound Assignment Operators. An extract:

    A compound assignment expression of the form E1 op= E2 is equivalent to E1 = (T)((E1) op (E2)), where T is the type of E1, except that E1 is evaluated only once.
    An example cited from §15.26.2

    [...] the following code is correct:

    short x = 3;
    x += 4.6;
    and results in x having the value 7 because it is equivalent to:

    short x = 3;
    x = (short)(x + 4.6);
    In other words, your assumption is correct.

Answer

NEWSLETTER

Enter your email address here always to be updated. We promise not to spam!