Java Reference
In-Depth Information
Here is the syntax for a two-way
if-else
statement:
if
(boolean-expression) {
statement(s)-for-the-true-case;
}
else
{
statement(s)-for-the-false-case;
}
The flowchart of the statement is shown in Figure 3.3.
true
false
boolean-
expression
Statement(s) for the true case
Statement(s) for the false case
F
IGURE
3.3
An
if-else
statement executes statements for the true case if the
Boolean-
expression
evaluates to
true
; otherwise, statements for the false case are executed.
If the
boolean-expression
evaluates to
true
, the statement(s) for the true case are exe-
cuted; otherwise, the statement(s) for the false case are executed. For example, consider the
following code:
two-way
if-else
statement
if
(radius >=
0
) {
area = radius * radius * PI;
System.out.println(
"The area for the circle of radius "
+
radius +
" is "
+ area);
}
else
{
System.out.println(
"Negative input"
);
}
If
radius >= 0
is
true
,
area
is computed and displayed; if it is
false
, the message
"Negative input"
is displayed.
As usual, the braces can be omitted if there is only one statement within them. The braces
enclosing the
System.out.println("Negative input")
statement can therefore be
omitted in the preceding example.
Here is another example of using the
if-else
statement. The example checks whether a
number is even or odd, as follows:
if
(number %
2
==
0
)
System.out.println(number +
" is even."
);
else
System.out.println(number +
" is odd."
);
