Why does bitwise AND of two short values result in an int value in Java?

Question

short permissions = 0755;
short requested = 0700;
short result = permissions & requested; 

I get a compiler error:

error possib         


        

Answer 1

The operands to the & operator will be promoted to int, and therefore the result is int, which will have to be casted to short if you want to store it in result. I don't think it should be a performance penalty unless the compiler is bad at generating code.

From http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#15.22.1:

When both operands of an operator &, ^, or | are of a type that is convertible (§5.1.8) to a primitive integral type, binary numeric promotion is first performed on the operands (§5.6.2).

From http://java.sun.com/docs/books/jls/third_edition/html/conversions.html#170983:

[...] Otherwise, both operands are converted to type int.