Java Reference
In-Depth Information
problems in Java. It is sometimes easier to declare the variables outside the block. If you
declare a variable outside a block, you can use it both inside and outside the block, and it
will have the same meaning both inside the block and outside the block.
TIP: Declaring Variables in a
for
Statement
You can declare a variable (or variables) within the initialization portion of a
for
statement, as in the following:
int
sum = 0;
for
(
int
n = 1; n < 10; n++)
sum = sum + n;
If you declare
n
in this way, the variable
n
will be
local to the
for
loop.
This means that
n
cannot be used outside the
for
loop. For example, the following use of
n
in the
System.out.println
statement is illegal:
for
(
int
n = 1; n < 10; n++)
sum = sum + n;
System.out.println(n);//Illegal
Declaring variables inside a
for
loop can sometimes be more of a nuisance than a
helpful feature. We tend to avoid declaring variables inside a
for
loop except for very
simple cases that have no potential for confusion.
■
Self-Test Exercises
4. Write a method called
happyGreeting
that could be added to the class
DateSecondTry
in Display 4.2. The method
happyGreeting
writes the string
"Happy Days!"
to the screen a number of times equal to the value of the instance
variable
day
. For example, if the value of
day
is
3
, then it should write the follow-
ing to the screen:
Happy Days!
Happy Days!
Happy Days!
Use a local variable.
Parameters of a Primitive Type
All the method definitions we have seen thus far had no parameters, which was indicated by
an empty set of parentheses in the method heading. A
parameter
is like a blank that is filled
in with a particular value when the method is invoked. (What we are calling
parameters
are
parameter
