Change the system time

Hello,
I would like to know if it is possible to change the system time.
If yes, how to do it ?
Thank.

@hugo ===
Could you explain more precisely what you want to do? Change the time format? change .locale?

Hello,
Thank you for your reply.
I would like, for example, that when we click on a button, we add 1 hour to the local time of the device.
Thank.

@hugo===
ok; but why that??? - I mean: if you want to change the time values inside your app and views (ie: you are displaying the hour but want that it can be changed) that is possible: you get the real time values and add or substract what you want before displaying. But if you want to “really” change the system hour on your phone that is not possible for 2 reasons 1) you need to get the SET_TIME permission which is a SYSTEM permission and cannot be obtained by an app which is not from the system itself. Of course you canroot your phone but…2) in many cases the time is set AUTOMATICALLY and as you cannot change this setting (by code) then you cannot change the real time…