Java Reference
In-Depth Information
ecute, and then actually executing it, control passes to the code follow-
ing the body of the
if
statement.
The example tests whether
hi
is even using the
%
, or
remainder,
oper-
ator (also known as the
modulus
operator). It produces the remainder
after dividing the value on the left side by the value on the right. In this
example, if the left-side value is even, the remainder is zero and the en-
suing statement assigns a string containing the even-number indicator
to
mark
. The
else
clause is executed for odd numbers, setting
mark
to an
empty string.
The
println
invocations appear more complex in this example because
the arguments to
println
are themselves expressions that must be eval-
uated before
println
is invoked. In the first case we have the expression
"1: "+ lo
, which concatenates a string representation of
lo
(initially
1
)
to the string literal
"1: "
giving a string with the value
"1: 1"
. The + op-
erator is a concatenation operator when at least one of its operands is
a string; otherwise, it's an addition operator. Having the concatenation
operation appear within the method argument list is a common short-
hand for the more verbose and tedious:
String temp = "1: " + lo;
System.out.println(temp);
The
println
invocation within the
for
loop body constructs a string con-
taining a string representation of the current loop count
i
, a separat-
or string, a string representing the current value of
hi
and the marker
string.
Exercise 1.7
: Change the loop in
ImprovedFibonacci
so that
i
counts
backward instead of forward.
