Package tweetoscope

Class HashtagCounter

java.lang.Object

tweetoscope.HashtagCounter

All Implemented Interfaces:

Flow.Publisher<Map<String,Integer>>, Flow.Subscriber<String>

public class HashtagCounter
extends Object
implements Flow.Subscriber<String>, Flow.Publisher<Map<String,Integer>>

Reacts to the reception of a new hashtag by updating how many times it has been seen so far, and sending to its subscribers the updated list of the most popular ones.

Hashtags are received via Java Flow from the upstream component

invalid reference

distributed_tweetoscope.HashtagExtractor

. Downstream component (

invalid reference

distributed_tweetoscope.Visualiazor

) is notified of the new leader board data via Java Flow.

Author:

Virginie Galtier

Field Summary

Fields

Modifier and Type	Field	Description
protected Map<String,Integer>	hashtagOccurrenceMap	Map invalid input: '<'Hashtag text - number of occurrences>
protected int	nbLeaders	Number of lines to include on the leader board
protected Map<String,Integer>	previousLeaderMap	List of most popular hashtags, used to checked if the list is changed after a new hashtag is received
protected List<Flow.Subscriber<? super Map<String,Integer>>>	subscribers	List of objects to notify when the map is updated (downstream component = Visualizor)

Constructor Summary

Constructors

Constructor	Description
HashtagCounter(int nbLeader)

Method Summary

Modifier and Type	Method	Description
void	onComplete()
void	onError(Throwable throwable)
void	onNext(String hashtag)	Triggered by the reception of a new hashtag from a TweetFilter via Java Flow.
void	onSubscribe(Flow.Subscription subscription)
void	subscribe(Flow.Subscriber<? super Map<String,Integer>> subscriber)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

subscribers

protected List<Flow.Subscriber<? super Map<String,Integer>>> subscribers

List of objects to notify when the map is updated (downstream component = Visualizor)

nbLeaders

protected int nbLeaders

Number of lines to include on the leader board

hashtagOccurrenceMap

protected Map<String,Integer> hashtagOccurrenceMap

Map invalid input: '<'Hashtag text - number of occurrences>

previousLeaderMap

protected Map<String,Integer> previousLeaderMap

List of most popular hashtags, used to checked if the list is changed after a new hashtag is received

Constructor Details

HashtagCounter

public HashtagCounter(int nbLeader)

Parameters:

nbLeaders - number of hashtags to include on the leader board

Method Details

subscribe

public void subscribe(Flow.Subscriber<? super Map<String,Integer>> subscriber)

Specified by:

subscribe in interface Flow.Publisher<Map<String,Integer>>

onNext

public void onNext(String hashtag)

Triggered by the reception of a new hashtag from a TweetFilter via Java Flow.

Specified by:

onNext in interface Flow.Subscriber<String>

onSubscribe

public void onSubscribe(Flow.Subscription subscription)

Specified by:

onSubscribe in interface Flow.Subscriber<String>

onError

public void onError(Throwable throwable)

Specified by:

onError in interface Flow.Subscriber<String>

onComplete

public void onComplete()

Specified by:

onComplete in interface Flow.Subscriber<String>