How can I ensure in Java that the current local time is correct? -
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i need make sure in client application user doesn't dramatically change machine date (e.g. bringing 1 month before).
to best of knowledge, best way check current time in java
system.currenttimeinmillis() how can make sure correct date, in multiplatform environment (either windows, linux, mac, etc.)?
no connection remote servers available, nor internet. also, @ startup time time tampered. need check time internal biz logic purpose, not set anything.
radio clock
obtain radio clock usb connection output of current time synchronized time code transmitted radio transmitter connected time standard such atomic clock. similarly, receiver of gps signals capture time signal.
the meinberg global company, @ least, offers several such devices.
sundial
position sundial outside window. attach webcam computer in question. position webcam in window. write app interpret time of day current image of sundial.
black box, no inputs = no go
more seriously, if not trust system time, have no access time server, , cannot ask user current time, cannot imagine solution. have black box no inputs. radio clock via usb adding such input.
wikipedia has article on clock synchronization.
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