Java Reference
In-Depth Information
boolean isDone(){
return done;
Set<Player> getRoster(){
return roster;
The idea behind the use of this class is that we will create a single object instance for each
team and StatRecorder object-containing host that we want to query. The run() method
of this object tries to contact the host that was supplied as part of the constructor to find a
StatRecorder server. If one is found, the method will then attempt to get the roster for the
Team whose name was given as part of the constructor. Once the method is finished, either
successfully or when an exception has been thrown, the boolean done is set to true and the
method (and the thread) finishes. Note that the run() method takes no parameters and returns
nothing; all of the work of setup is accomplished before the method is called, and all of the
results are stored as part of the object state. In this sense, a method like this is something like
the completions found in other languages. But the real reason to have such an object is to al-
low it to be run concurrently with other things that our program might be doing.
We can then call start() on a RosterRetriever object, which will execute the run() meth-
od. The start() method will return as soon as the thread is started, and we can run in paral-
lel with that thread in our main program. When we actually need the roster, we will first see
whether the work is complete by calling isDone() . If the result we get back is true , we can
then call getRoster() . If the result of this call is null , we know that something went wrong.
But if we get a Set of Player objects back, we will have gotten the roster for the team in
parallel with doing other things.
We can make RosterRetriever an inner class that is seen only in the scope of the StatRe-
porterImpl object. This will ensure that only individual objects of the StatReporterImpl
class will use this kind of object. To use a RosterRetriever , we could add a method to the
StatReporterImpl that looks something like:
* Create and start a {@link RosterRetriever}. The created object
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