CountdownPublicationServiceImpl.java :  » App » skylight1 » net » nycjava » skylight1 » service » impl » Android Open Source

package net.nycjava.skylight1.service.impl;

import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;

import net.nycjava.skylight1.service.CountdownObserver;
import net.nycjava.skylight1.service.CountdownPublicationService;

public class CountdownPublicationServiceImpl implements CountdownPublicationService {

  private int duration = 0;

  private int currentCount = 0;

  private boolean stopRequested = false;

  private Set<CountdownObserver> countdownObservers = new HashSet<CountdownObserver>();

  private CounterStatus currentStatus = CounterStatus.uninitialized;

  private Timer countdownTimer;

  public void addObserver(CountdownObserver anObserver) {
    countdownObservers.add(anObserver);
    if (this.currentStatus == CounterStatus.running) {
      int remain = getRemainingTime();
      notifyObservers(remain);
    }
  }

  public boolean removeObserver(CountdownObserver anObserver) {
    final boolean existed = countdownObservers.remove(anObserver);
    return existed;
  }

  public void setDuration(int seconds) {
    duration = seconds;
  }

  private int getRemainingTime() {
    int aRemainingTime = this.duration - currentCount;
    return aRemainingTime;
  }

  class CountdownTask extends TimerTask {
    public void run() {
      if (duration == 0)
        return;
      currentStatus = CounterStatus.running;
      if (currentCount < duration && stopRequested == false) {
        currentCount = currentCount + 1;
        notifyObservers(getRemainingTime());
//        System.out.println("start counting: " + currentCount);

      }
      if (currentCount == duration) {
        currentStatus = CounterStatus.finished;
      }

      if (stopRequested) {
        currentStatus = CounterStatus.stopped;
      }
    }
  }

  public void startCountdown() {
    if (this.duration == 0) {
      // should be an assertion here
      return;
    }

    else if (this.currentStatus == CounterStatus.running) {
      // should assert here as well
      return;
    }
    countdownTimer = new Timer();
    CountdownTask countdownTask = new CountdownTask();
    long zeroDelay = 0;
    countdownTimer.scheduleAtFixedRate(countdownTask, zeroDelay, 1000);
  }

  public void stopCountdown() {
    stopRequested = true;
    if (countdownTimer != null) {
      countdownTimer.cancel();
    }
    currentStatus = CounterStatus.stopped;
  }

  private void notifyObservers(int aRemainingTime) {
    //Fix ConcurrentModificationException by copying the list before iterating over it.
    //This protects us from any changes that happen during the iteration.
    List<CountdownObserver> countdownObserversSnapshot = 
      new LinkedList<CountdownObserver>(countdownObservers);      
    for (final CountdownObserver countdownObserver : countdownObserversSnapshot) {
      countdownObserver.countdownNotification(aRemainingTime);
    }
  }

  @Override
  public CounterStatus getStatus() {
    return currentStatus;
  }

}