I have managed to read the web service to get current time of any given city.
I could get 2 important values from web service, current time (String) and the offset.
Question is
How to set time of any given city correctly?
Option 1:
Read machine/local time
Calculate UTC/GMT time out of machine time
City time = UTC time +/- offset value
But then what happens when machine time is wrong? You will also got
wrong time right?
Option 2:
Read current city time in String (2012-11-24 19:30)
Parse this time value and set it into Calendar
We got correct City time
But how about the next minute? Of course requesting the web service every minute to get current time is not a good solution right? Is it possible to maintain this Calendar instance keep running automatically every minute once we set it?
NB : I'm developing Android clock widget here.
Thanks
Option 1 is far better, in my eyes. Most cell phones have amazingly accurate time as time synchronization is an integral part of GSM and CDMA. Beyond that, I would far prefer a clock to work offline than to require internet connectivity.
If you are worried about ensuring accuracy in the face of incorrect system time, consider placing a call to a web service to get the current time for verification.
This verification could be done in the background, but keep in mind that web services are not the best time sync providers. I would let anything with under 5 minute difference go as it could be due to your server being out of sync or the call taking too long.
Related
I have an app which, among other things, continuously publishes current time in milliseconds since epoch (System.currentTimeMillis()).
What I want to do is write a query in grafana dashboard such that:
a) It shows "Up" if the difference between current time in grafana & my published time is less than 1 min.
b) Shows "Down" is the above query doesn't hold or there is no data.
Any ideas, pointers will be most helpful.
Thanks
Well, you could pass the value of your real timestamp to grafana, as a "long" or "timestamp" field , named real_ts (maybe there's another way, sorry, not expert in grafana).
Then, substract grafana's timestamp with your real_ts field's value, and if >60 seconds, print Down, if not, print Up.
Is there any way to get the results like in this link having wrong date and time set on device? Thank you.
There's a way1 ...
Suppose that you have deliberately set the clock 1 minute slow.
Create a file that contains the number 60,000. When an application wants to find the correct time, it calls System.getTimeMillis() to get what the system thinks the time is. Then reads the number from the file and adds that number to the result of System.getTimeMillis().
Clearly, this is NOT a good idea, but then neither is deliberately setting the system clock incorrectly. (For a start, if the clock is miss-set, then you will have difficulty syncing it with an external time source like an NTP server. That means that your system's clock will drift.)
The problem i am working on is the TOTP algorithm. The thing I was wondering is how would it work if the time on server and the one on the device are not the same.
I see. The answer is that TOTP cannot work if the two clocks are not synchronized to within a small multiple of the timestep.
1 - There's another way too. Write an application that can do some image processing on a picture of a clock to read the time. Then hook this up to your computer's video camera, and point the camera at a cuckoo clock hanging on your wall. Make sure you wind up the clock regularly. If you want the date as well, point a second video camera at your Dilbert desk calendar.
Is it possible in Android to get a time / date, which can not be manipulated by the user?
I mean in Android you can edit the system time and if you remove the battery the time is reseted too. Of course you can get the current time from a server on the internet but (improbable but is would work) then the user is able to intercept the request and send an own time back.
I do not know much about GPS. Is there a time stamp and is it possible that the user can replace it? I really want a time which can definitely not be changed by the user. Is that possible?
You can never trust the client. If this is really as absolutely crucial as you're saying, see if it's possible to offload whatever it is you're doing to a server that's under your control.
I am trying to license my product(java app) with a simple technique by comparing two dates.I want to know how should I increment the date when I give the app to my client.I need to increment the date everyday,so that when it expires it doesnt work.
I dont want to use the system date,cause there are chances the client might change that.So could anyone provide me any suggestions.
Since the java app is going to be running on your client, you have basically two options (simplistically speaking).
Option1. Use a (possibly) encrypted file on your client's filesystem to store the date you want to store and compare against your expire date.
Option2. Upon registering, register to a server. Now the server knows when you registered, so it should be able to determine when you expire. Each time the application starts, make a call to the server asking if it has expired. This way, you have transferred part of the expiry logic to the server.
Keep in mind that both approaches in their simplistic form can be easily circumvented but that is most of the time the case when you have an app running on clients' computers.
One way i can think of is
Use webservice to get current date in your client
earthtools.org provides a free web service to get the time zone from a city here:
http://www.earthtools.org/webservices.htm#timezone
You just pass in the long/lat values like this: (This is for New York)
http://www.earthtools.org/timezone-1.1/40.71417/-74.00639
Use java Rest client to get date in your code
http://www.mkyong.com/webservices/jax-rs/restfull-java-client-with-java-net-url/
I am trying to conduct some extremely accurate data measurements. For this, I need to be able to get the current time in microseconds, accurate to 100 microseconds (Or more). I can't seem to be able to find any way on the Android Developer website. Device specific answers are acceptable (I have access to a Nexus 7, so any answers involving that would be awesome).
I had originally thought it possible to use the system sensors which give times accurate to the microsecond, however I have no idea how to set and/or tell if the sensors are accurate. Not to mention whether these event. - SensorManager
Is there any way to get the time in microseconds on an android device that is accurate to within 100microseconds?
you can use System.nanoTime(). according to doc
Returns the current timestamp of the most precise timer available on
the local system. This timestamp can only be used to measure an
elapsed period by comparing it against another timestamp. It cannot be
used as a very exact system time expression.
Returns
the current timestamp in nanoseconds.
From the java doc here you will get some extra explanation of it