Java Reference
In-Depth Information
System.out.print(trueExp ? alpha : ((char) i)); // Prints A
}
}
When the value of
i
in the second conditional expression falls outside the range that
can be represented as a
char
, the explicit cast will truncate its value. This usage complies
with exception NUM12-EX0 of NUM12-J, “Ensure conversions of numeric types to nar-
rower types do not result in lost or misinterpreted data” in
The CERT
®
Oracle
®
Secure
Coding Standard for Java
™
[Long 2012].
Noncompliant Code Example
This noncompliant code example prints 100 as the size of the
HashSet
rather than the ex-
pected result (some value between 0 and 50):
public class ShortSet {
public static void main(String[] args) {
HashSet<Short> s = new HashSet<Short>();
for (short i = 0; i < 100; i++) {
s.add(i);
// Cast of i-1 is safe,
// because value is always representable
Short workingVal = (short) (i-1);
// ... Other code may update workingVal
s.remove(((i % 2) == 1) ? i-1 : workingVal);
}
System.out.println(s.size());
}
}
The combination of values of types
short
and
int
in the second argument of the con-
ditional expression (the operation
i-1
) causes the result to be an
int
, as specified by the
integer promotion rules. Consequently, the
Short
object in the third argument is unboxed
intoa
short
,whichisthenpromotedtoan
int
.Theresultoftheconditionalexpressionis
thenautoboxedintoanobjectoftype
Integer
.Becausethe
HashSet
containsonlyvalues
of type
Short
, the call to
HashSet.remove()
has no effect.
