SchedulerTask.java

package carpool.clean;

import java.util.TimerTask;

public abstract class SchedulerTask implements Runnable {

    final Object lock = new Object();

    int state = VIRGIN;
    static final int VIRGIN = 0;
    static final int SCHEDULED = 1;
    static final int CANCELLED = 2;

    TimerTask timerTask;

    protected SchedulerTask() {
    }

    public abstract void run();

    public boolean cancel() {
        synchronized(lock) {
            if (timerTask != null) {
                timerTask.cancel();
            }
            boolean result = (state == SCHEDULED);
            state = CANCELLED;
            return result;
        }
    }

    public long scheduledExecutionTime() {
        synchronized(lock) {
         return timerTask == null ? 0 : timerTask.scheduledExecutionTime();
        }
    }

}