Java Reference
In-Depth Information
On the other hand, you should leave the following
for
loop as is and not attempt to
convert it to a for-each loop:
for
(
int
i = 0; i < a.length; i++)
a[i]= 2*i;
Because this
for
loop uses the index
i
in the body of the
for
loop and uses it in an
essential way, it does not make sense to convert this
for
loop to a for-each loop.
For-Each Loop for Arrays
SYNTAX
for
(
Array_Base_Type Variable
:
Array_Name
)
Statement
EXAMPLES
for
(
double
element : a)
sum += element;
The array
a
has base type
double
. This for-each loop sets each element of the array
a
to
0.0
.
A good way to read the first line of the example is “For each
element
in
a
, do the following.”
Methods with a Variable Number of Parameters
★
Because of overloading, you can have a method named
max
that returns the largest of
two
int
values and have another method named
max
that takes three
int
arguments
and returns the largest of the three. If you decide you need a method that returns the
largest of four
int
values, you can define a version of the method
max
that takes four
arguments. However, with this approach, there is no way to cover all cases of computing
the maximum of some number of
int
values. Covering all cases in this way would
require an infinite number of definitions for the method name
max
, and no programmer
has enough time to write an infinite number of definitions. What we would like is a
single method definition for a method named
max
that can take any number of
int
arguments. Starting with version 5.0, Java lets you define methods that take any number
of arguments. For example, the following is the definition of a method named
max
that
takes any number of
int
arguments and returns the largest of its arguments:
public static int
max(
int
... arg)
{
if
(arg.length == 0)
{
System.out.println("Fatal Error: "+
"maximum of zero values.");
System.exit(0);
}
