Java Reference
In-Depth Information
static double tanh(double x) {
return (exp(x) - exp(-x)) /
(exp(x) + exp(-x));
}
A static import statement consists of the keyword phrase
importstatic
, followed by the fully qualified name of the class or interface you are
importing the static member from, a dot and then the static member's
name. Like all statements it is terminated by a semicolon.
A
static import on demand statement
uses an asterisk (
*
) instead of
a member name. This tells the compiler that if it finds names that it
doesn't know about, it should look at the type given by the static import
on demand statement to see if it has a static member by that name.
If so, the compiler will assume that you intended to refer to the stat-
ic member. For example, if our hyperbolic tangent function were part
of a class that defined many mathematical functions and used many of
the static methods and constants of the
Math
class, then we might use
a static import on demand statement to import all of those method and
constant names:
import static java.lang.Math.*;
When names can be imported in this way it is easier for naming conflicts
to occur. There are various rules about how static import and static im-
port on demand work with each other and with the other names used in
your program. These are explained in more detail in "
The Meanings of
The use of static imports can help the readability of your code, but if
misused they can also make it harder to understand what your code is
doing. When the reader sees
Math.exp
it is quite evident what is being
referred to, but a simple
exp
is not so clear. If you have multiple static
import on demand statements, the reader will have to look up each of
the types to see if they have a static member named
exp
. As a general
