Develop Reference

Getting date and time which user can not change

I am currently developing an app that used for write some document and send them to a database. Issue is app need to get date and time automatically when form created and users can modify system date & time.
First, I search for solution on the internet, then one of the solutions is using a service that return time and later on count that time, so time can not be modified by user. This solution will not for this app because users can be in a place that do not have cell reception or internet access, so app need to work without internet access as long as sending data to remote database via internet.(date of form must be the time when form created)
Second idea is about network-provided time and time zone. If user want to change, he or she must disable those setting then modify time. I think when user want to write a form, app will check whether it is on or off. If it is of app will show an alert dialog which force them to activate those settings.
So I tested, I turned off wifi and cellular, turned off those setting, modified time and waited for a couple minutes. Then I turned on those setting and system showed correct time.
Also, after system corrected its date and time without network connection when I activated network-provided time and time zone setting, It made me think maybe app can get date from a place that user can not modify, yet I could not find information about this.
So I am looking for reliable method, and open for new ideas. If there was not I will implement second method.
Thank all of you who spared their time and read this.
And Second solustion will look like this:
private boolean isTimeZoneAutomatic(Context c) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
return Settings.Global.getInt(c.getContentResolver(), Settings.Global.AUTO_TIME_ZONE, 0) == 1;
} else {
return android.provider.Settings.System.getInt(c.getContentResolver(), Settings.System.AUTO_TIME_ZONE, 0) == 1;
}
}
Do you have any suggestion?

Time since first boot up

I'm developing an android application and hit the problem with determining system first boot up time. I mean i need to measure how much time already passed from device first boot up.
I know about solution with listening for ACTION_BOOT_COMPLETED and save anything in SharedPreferences, but i need another solution, because this one does not work for some cases. Maybe there is any system property?
Use case (excerpt from discussion)
The filename of each file I receive from server includes a timestamp
taken from System.currentMillis()
I compare those timestamps in order to determine, which file the most current one is.
Now, the user changes system time a few months ahead.
I am still able to determine the most current file downloaded after user changed system time.
Now, the user changes time back to original setting.
The file downloaded on step 4 always wins when comparing timestamps.
The silver bullet to solve this problem would be a timestamp that counts seconds since first boot (after factory reset). Just like SystemClock.elapsedRealtime() but without reset after each boot. Unfortunately, the answers so far tell us, that this silver bullet doesn't exist.
However, many answers show a great variety of options how to tackle that problem. OneWorld123 commented each answer, how that suited his needs.

Maybe there is any system property?
Not sure about system property, but there is SystemClock class which provides API's to get system uptime:
SystemClock.uptimeMillis() which
Returns milliseconds since boot, not counting time spent in deep sleep.
You may also use SystemClock.elapsedRealtime() which
Returns milliseconds since boot, including time spent in sleep.
Hope this helps.

In case one needs to know when was the first time an Android device was booted,
The easiest method would be to have an application
that is installed in the factory image
that is configured to run during boot
that logs the current date & time into a sharedPreference on its first run
Subsequently any other apps that need to determine the first boot time of the Android device can lookup the appropriate sharedPreference during the lifetime of the device. (or until the device is factory-reset; at which point the pre-installed app would write the new date&time into the shared preference after a reboot.)
However if it is not possible to an pre-install an application on the Android device, then a couple of potential workarounds would be:
1. As a root/superuser
one would lookup the time-stamp of a directory/file that is known to get created on the Android device during first-boot.
2. As a regular app,
a simple workaround method using standard Android APIs would be to check for the installation-time of an appropriate system package that is known to get installed during first-boot.
/* This returns the last time a package was installed */
PackageManager pm = context.getPackageManager();
PackageInfo pInfo = pm.getPackageInfo(<app-package-name>, 0);
return pInfo.firstInstallTime;
3. Alternately as a regular app,
if we can rely on a specific package being updated one-time during first-boot (and never again) we can check its update-time as follows:
/* This returns the last time a package was updated */
PackageManager pm = context.getPackageManager();
ApplicationInfo appInfo = pm.getApplicationInfo(<app-package-name>, 0);
String appFile = appInfo.sourceDir;
long installed = new File(appFile).lastModified();

If we stick to the SDK, I don't know of a method providing this information directly; but there might be a way to derive this information from other resources. Again, if we stick to SDK, one "rather reliable" option is to use application usage statistics which Android OS saves during device lifetime. That is - the timestamp for a first "usage stats" ever saved.
This, though, clearly does not provide an exact "first boot time" timestamp, so it depends on whether some approximation is OK in your case. Generally, the problem with usage statistics is that Andriod aggregates it for periods distant in time - so, the older device is - the less accurate the date is. For example, for my current phone, first booted on Dec. 3 2014, aggregated usage statistics is first recorded on Dec. 21 2014 currently (for the record - it is Feb. 2016 by the time of this writing). (I have to admit though that I don't know how Android OS schedules the aggregation, and if it is just scheduled on Dec. 21 every year, or if it is indeed somewhat close to the first device usage - I guess it is easy to check with any other device.)
Following is some sample code showing UsageStatsManager usage, but it certainly would need more adjustments in order to address the fact of having more precision for more recent periods:
UsageStatsManager usageStatsManager = (UsageStatsManager) context.getSystemService(Context.USAGE_STATS_SERVICE);
Calendar year2013 = Calendar.getInstance(); year2013.set(2013, 0, 1);
List<UsageStats> stats = usageStatsManager.queryUsageStats(
UsageStatsManager.INTERVAL_YEARLY, // or adjust for "younger" devices to get more precision - so, you'll probably need several queries
year2013.getTimeMillis(),
Calendar.getInstance().getTimeInMillis());
// now, first element in stats (if it is present at all) will point to the "earliest" statistics saved *for this interval* (yearly in this case)
// use UsageStats.getFirstTimeStamp() to get first known/saved usage
Note also that, as documented in the SDK, UsageStatsManager requires PACKAGE_USAGE_STATS system-level permission, so you'll need to make user accept it in Settings first:
Intent settingsIntent = new Intent(Settings.ACTION_USAGE_ACCESS_SETTINGS);
startActivity(settingsIntent);
Hope it helps!

According to your discussion on: https://chat.stackoverflow.com/rooms/102325/discussion-between-ankitagrawal-and-oneworld , you need a monotonic counter to uniquely identify a dataset.
For that you can easily set a SharedPreference and increment this value every time you need a new identifier. When you require to know which is the newest file, just compare the identifiers. If it is an issue that this counter gets reset once the app is uninstalled, please refer to: In android is there any way to preserve SharedPreferences after an uninstall
A different approach that could be used, is to request a timestamp from an outside server.
Hope it helps ;-)

There are 3 methods in ANDROID SDK for these:-
public static long elapsedRealtime ()
Added in API level 1
Returns milliseconds since boot, including time spent in sleep.
Returns
elapsed milliseconds since boot.
public static long elapsedRealtimeNanos ()
Added in API level 17
Returns nanoseconds since boot, including time spent in sleep. Returns
elapsed nanoseconds since boot.
For #oneWorld Case:
You can use 2 approach:-
1) While writing check if some data has date above the current date then change the date of previous data to something less than current data and time,
so it will return correct latest data.
2) You can store the time on server and retrieve time from there and set it.

Time that does not depend on user preference

Is there a way to get today's date and time such that it corresponds to the real world date/time and is not affected if the user has changed the date/time settings on their phone/web browser?
If not, is using a server time the best way to correctly determine today's date on the phone? Or are there other best practices?

if you don't want to use a server time, u can parse the return of gettime() link

Server time suits most of the needs. Then if your server's time is messed up then you will be in problem.
Alternatively, you can use some third party web service to provide you with the time.
For example
https://developers.google.com/maps/documentation/timezone/
Google being a reputed company, the time returned can be trusted to be correct.

I'd never trust a user's device to retrieve time related information.
Get the UTC time from the server and if required, display it to the user converted to his time zone. Here's a so question on how to convert UTC time to local time with JS
This way your stored time will always be ok and in same "format". The only thing that could happen is that the ends up seeing a "wrong" time, if he faked his location / time zone settings. But I wouldn't mind that.

Creating a unique date each time between calls

I am writing a Java program using selenium. I need a function that returns a unique date (mm/dd/yyyy) each time it is called. The conditions though are that
It can never return a date it returned before
Is must return a date between 01/01/2071 and 12/31/9999
The program will run many times so all program memory will be lost upon termination. It
must remember the dates it has returned before. See next item
The easiest way to do this is just keep incrementing the date by 1 day each time, so it
needs to remember only 1 date.
Unfortunately I cannot write the last date returned to a file in the system to read it
next time the program runs because I do not have that ability.
The program will be reading data from an Excel spreadsheet so could theoretically store
the latest date in a cell, but the spreadsheet will be open and it does not seem to
have the ability to write to an open file.
Any thoughts? One thing I thought about doing was using a base date like 1/1/2014 at 00:00:00 and then taking the current date, calculating the number of minutes between the two, and adding this as a number of days to 11/31/2070. Unfortunately this would work only a couple of years because then there would be more minutes between the two dates than there are days from 1/1/2017 to 12/31/9999
Any help is appreciated.
Thanks

Change link to download every 7 days?

I'm downloading a certain website in html format to my device, so that I can display it in webview in offline mode. The only problem is that the link is dynamic, and it changes once a week. To keep the html item updated as much as possible, I want the app to download it once a week.
Let's say for example that this is the websites address:
www.mywebsite.com/1
Next week, the address will be:
www.mywebsite.com/2
And week after that, the website will be:
www.mywebsite.com/3
I already figured I would do this be declaring a variable that would be changing, something like
int week;
String urlToDownload = "www.mywebsite.com/" + week;
But how do I make it so that this variable will change everyday even if the app is not started, or is there a better way to do this?

You can maybe use AlarmManager class. That allows you to plan something on the background, when app is not even running.
I would use the most simple solution. Do you know what time does the URL change? You can always check the time of previous start of application and when next app is started check it and determine how many weeks is from that.

Use the java.util.Calendar
Calendar calender = Calendar.getInstance();
MyLog.d("Current Week:", "" + calender.get(Calendar.WEEK_OF_YEAR));
This prints "Current Week: 37"
With that maybe you can write code to get the appropriate page. The week nr are kind of static

You can update the variable during the onStart() phase. Make a constant that has the start date, and then get the current date and figure out the offset. This way even if the app hasnt been started in a long time, once it is started you will have the proper link.