android开发 系统时间与定时器之间有关系嘛？

如题：

android开发 系统时间与定时器之间有关系嘛？

答案：有。

看定时器源码：

/*
     * Schedule a task.
     */
    private void scheduleImpl(TimerTask task, long delay, long period, boolean fixed) {
        synchronized (impl) {
            if (impl.cancelled) {
                throw new IllegalStateException("Timer was canceled");
            }

            long when = delay + System.currentTimeMillis(); if (when < 0) {
                throw new IllegalArgumentException("Illegal delay to start the TimerTask: " + when);
            }

            synchronized (task.lock) {
                if (task.isScheduled()) {
                    throw new IllegalStateException("TimerTask is scheduled already");
                }

                if (task.cancelled) {
                    throw new IllegalStateException("TimerTask is canceled");
                }

                task.when = when;
                task.period = period;
                task.fixedRate = fixed;
            }

            // insert the newTask into queue
            impl.insertTask(task);
        }
    }