Java Reference
In-Depth Information
}
}
StubFinder
loads a classfile whose name is specified as a command-line argu-
ment, and outputs the metadata associated with each
@Stub
annotation that precedes
annotation type.
StubFinder
nextusesaspecialclassnamed
Class
(inthe
java.lang
package)
and its
forName()
class method to load a classfile.
Class
also provides a
getMethods()
methodthatreturnsanarrayof
Method
objectsdescribingtheloaded
class's public methods.
For each loop iteration, a
Method
object's
isAnnotationPresent()
method
is called to determine if the method is annotated with the annotation described by the
Stub
class (referred to as
Stub.class
).
If
isAnnotationPresent()
returns true,
Method
's
getAnnotation()
method is called to return the annotation
Stub
instance. This instance's
value()
method is called to retrieve the string stored in the annotation.
Next,
String
's
split()
methodiscalledtosplitthestring'scomma-separatedlist
ofID,date,anddevelopervaluesintoanarrayof
String
objects.Eachobjectisthen
output along with descriptive text.
Class
's
forName()
method is capable of throwing various exceptions that must
behandledorexplicitlydeclaredaspartofamethod'sheader.Forsimplicity,Ichoseto
append a
throws Exception
clause to the
main()
method's header.
Caution
Therearetwoproblemswith
throws Exception
.First,itisbetterto
handle the exception and present a suitable error message than to “pass the buck” by
throwing it out of
main()
. Second,
Exception
is generic—it hides the names of
thekindsofexceptionsthatarethrown.However,itisconvenienttospecify
throws
Exception
in a throwaway utility.
Do not be concerned if you do not understand
Class
,
forName()
,
getMeth-
ods()
,
Method
,
isAnnotationPresent()
,
.class
,
getAnnotation()
,
After compiling
StubFinder
(
javac StubFinder.java
),
Stub
(
javac
StubFinder
with
Deck
asitssinglecommand-lineargument(
java StubFinder
Deck
). You will observe the following output:
