protected LinkedList<Task> checkTasks() {
        LinkedList<Task> onsetTasks = new LinkedList<Task>();
        for (Task task : model.getTaskList()) {
            if (!task.isActive())
                continue;
            Date presentTime = new Date();

            if (task.nextTimeAfter(presentTime) == null) {
                if (task.isActive()) {
                    onsetTasks.add(task);
                }
                continue;
            }

            Date taskTime = task.lastTimeBefore(presentTime);
            if (taskTime != null && presentTime.after(taskTime)) {
                onsetTasks.add(task);
            }
        }
        return onsetTasks;
    }