How to set mobile system time and date in android?

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You cannot on a normal off the shelf handset, because it’s not possible to gain the SET_TIME permission. This permission has the protectionLevel of signatureOrSystem, so there’s no way for a market app to change global system time (but perhaps with black vodoo magic I do not know yet).

You cannot use other approaches because this is prevented on a Linux level, (see the long answer below) – this is why all trials using terminals and SysExecs gonna fail.

If you CAN gain the permission either because you rooted your phone or built and signed your own platform image, read on.

Short Answer

It’s possible and has been done. You need android.permission.SET_TIME. Afterward use the AlarmManager via Context.getSystemService(Context.ALARM_SERVICE) and its method setTime().

Snippet for setting the time to 2010/1/1 12:00:00 from an Activity or Service:

Calendar c = Calendar.getInstance();
c.set(2010, 1, 1, 12, 00, 00);
AlarmManager am = (AlarmManager) this.getSystemService(Context.ALARM_SERVICE);
am.setTime(c.getTimeInMillis());

If you which to change the timezone, the approach should be very similar (see android.permission.SET_TIME_ZONE and setTimeZone)

Long Answer

As it has been pointed out in several threads, only the system user can change the system time. This is only half of the story. SystemClock.setCurrentTimeMillis() directly writes to /dev/alarm which is a device file owned by system lacking world writeable rights. So in other words only processes running as system may use the SystemClock approach. For this way android permissions do not matter, there’s no entity involved which checks proper permissions.

This is the way the internal preinstalled Settings App works. It just runs under the system user account.

For all the other kids in town there’s the alarm manager. It’s a system service running in the system_server process under the – guess what – system user account. It exposes the mentioned setTime method but enforces the SET_TIME permission and in in turn just calls SystemClock.setCurrentTimeMillis internally (which succeeds because of the user the alarm manager is running as).

Cheers

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