Operators and Expressions - The Java Programming Language - page 298

9.1.1. Integer Arithmetic
Integer arithmetic is modular two's-complement arithmeticthat is, if a
value exceeds the range of its type ( int or long ), it is reduced modulo
the range. So integer arithmetic never overflows or underflows but only
wraps.
Integer division truncates toward zero ( 7/2 is 3 , and -7/2 is -3 ). For in-
teger types, division and remainder obey the rule
(x/y)*y + x%y == x
So 7%2 is 1, and -7%2 is 1. Dividing by zero or remainder by zero is invalid
for integer arithmetic and throws ArithmeticException .
Character arithmetic is integer arithmetic after the char is implicitly con-
verted to int see " Expression Type " on page 215 .
9.1.2. Floating-Point Arithmetic
Floating-point arithmetic can overflow to infinity (become too large for
a double or float ) or underflow (become too small for a double or float ).
Underflow results in a loss of precision, possibly enough to yield a zero
value. [1] The result of an invalid expression, such as dividing infinity by
infinity, is a NaN valuefor "Not-a-Number."
[1] Detecting non-zero underflows is a non-trivial task that is beyond the scope of this topic.
Arithmetic with finite operands performs as expected, within the limits of
precision of double or float . Signs of floating-point arithmetic results are
also as expected. Multiplying two numbers having the same sign results
in a positive value; multiplying two numbers having opposite signs res-
ults in a negative value.