问题
I have a independent clock created in my application. The clock runs as a different thread in the activity, starting from a base time set by me. I update the clock using the difference between the uptimemillis when I set the clock, and the current uptimemillis. But the uptimetimer, can be reset by Android, and is ever reset when Android reboot.
I only want to know if the uptime timer is reset, to know if the clock is still reliable.
How?
回答1:
According to the documentation you can use SystemClock.elapsedRealtime()
elapsedRealtime(): Returns milliseconds since boot, including time spent in sleep.
This value will only be reset when the device is restarted. Listen to the broadcast boot_complete and you will know when that is.
The problem with the updateMillis() is clearly noted in the documentation:
uptimeMillis(): Returns milliseconds since boot, not counting time spent in deep sleep. Note: This value may get reset occasionally (before it would otherwise wrap around).
From how I understand the documentation, by using elapsedRealtime your users cannot manipulate your counter.
来源：https://stackoverflow.com/questions/16255288/know-if-uptime-timer-is-reset-or-android-has-been-rebooted