Develop Reference

How to track system's clock?

Situation:
I need to create a program that shows current date and updates some date(that is NOT CURRENT date,it is past date) according to current time(for example after 23:59,date refreshs). In other words,it is simple application,that shows date in the past and time.
What did I try?
I have found TextClock for this. It can show current time,but I cannot track over it.
So what can I do? I need to create my own clock class or use Timer and TimerTask? Do I need a Service?

I think, if I understand you correctly, you're on the right path. I wasn't familiar that there was even a TextClock view, but it looks pretty basic and will just work for displaying the current time.
Instead, maybe use a TimerTask to update the UI every second, or so, and set one TextView with the current time and another with your other time that's an offset of the current time (current = new Calendar(); current.add(Calendar.MINUTE, 1); )
You could use TimerTask, and that'd be pretty easy compared to rolling your own thread or using an AsyncTask. Get the current time, set it to one text view, manipulate that time variable and set it to the other text view.

update textview from couchdb using changelistener android

I am trying to get real time changes on a document using the changelistener, however i have to refresh tha mobile app to see the change. Here is my gist https://gist.github.com/mikekaraa/89416ea8b074c71d7153
Please help me out if you have a solution

Would you tie your ChangeListener() event to a time interval such that e.g after every 3 or 5 seconds it is fired and triggers the next sequence of events if at all the document changed within that time span.
I hope that helps.

Changing preference in OnPreferenceChangeListner in android

In my android app, I need settings to select time range (e.g. 2 to 4 minutes, 8 to 12 minutes etc).
To implement it, I used two instances of ListPreference, one to select minimum time and other to select maximum time.
As maximum time cannot be less than minimum time, I want to update the maximum time list preference whenever minimum time is changed by a user.
To achieve it, I am using Preference.OnPreferenceChangeListner. When user changes minimum time preference, the listener callback function is called and in the callback, I call setEntries(), setEntryValues() and setValueIndex() on maximum time ListPreference instance.
The problem is that GUI of maximum time preference is not updated immediately when I do above. I can still see old entries in the preference. If I exit settings activity and launch the settings again, I can see updated entries and values.
Please let me know how I could solve this issue.
Also, please suggest if there is any better way to handle such settings use case.
Thanks.

After some more debugging, I realized my mistake.
I did not read this document of OnPreferenceChangeListener callback:
"Called when a Preference has been changed by the user. This is called before the state of the Preference is about to be updated and before the state is persisted."
The problem was that I was querying the value of minimum time list preference in the preference change listener callback of it and generating the entries of maximum time list preference on the bases of that. But as the document reads, new value of minimum time list preference was not yet set in the callback, so the entries were generated on the basis of old values. So it was not supposed to work as I was expecting.
Sorry for not posting code as it required more effort to make the code ready for posting here.
Thanks for reading my question.

Android Chronometer start with defined value

I have an application in which I'm displaying a chronometer to the user for what he's doing.
Whenever the activity goes to the background (wether by home button, or back) I save that time (in seconds) and when the activity is brought back, I want to continue the chronometer running from the same time. The user might select a different item from the list, and the time is different, and also he might turn off the phone...
I can save the time of the chronometer, however I can't set it with a start time.
From the Chornometer API, the method setBase() states:
Set the time that the count-up timer is in reference to.
On my understanding, this means that if I set this value to currentTime, it'll start counting with 0.
Now, if I want it to start with the value 17s I thought about setting the base to the currentTime less the time 17 seconds ago. So something like:
setBase(system.currentTimeMillis() - (17 * 1000)).
However this doesn't work, and the it starts always with 0!
I read a few other threads around here, and none of the answers helped. It always starts with 0!
Thanks in advance.

I think you're going to have to keep track of some time marks yourself.
Chronometer myChrono;
long baseTime;
long stopTime;
long elapsedTime;
When you set the base time, you want to use:
baseTime = SystemClock.elapsedRealtime() - stopTime;
myChrono.setBase(baseTime);
When you want to see how much time has passed, use:
elapsedTime = SystemClock.elapsedRealtime() - myChrono.getBase();
Take a look at the SystemClock doc.

setBase(system.currentTimeMillis() - (17 * 1000))
Should be changed to
setBase(SystemClock.elapsedRealtime() - (17 * 1000))
In general:
mChronometer.setBase(SystemClock.elapsedRealtime() - (nr_of_min * 60000 + nr_of_sec * 1000)))
Hopefully this will save lots of u folks some time :)

android game - keeping track of time

I have a puzzle game for android. When the puzzle starts I take the current time:
long startTime = System.currentTimeInMillis()
When the player completes the puzzle, I take the time again, subtract the starting time and work out the elapsed time. This is all ok.
My problem is what to do when the application is interrupted. For example by a phone call. At the moment, the puzzle remains in it's previous state automatically (as it is in a view). However, the calculation completionTime = currentTime - startTime will now be invalid.
I have tried saving the elapsed time using onSaveInstaceState(Bundle). However its counterpart, onRestoreInstanceState(Bundle) is not called when re-entering the app. Rather, the onResume() method is called instead? I have read this is because the app has not been 'killed', rather it is still in memory. In the case of a 'kill', I'd imagine the state of the View will also be lost? I don't think it's terribly necessary to keep track of the view in this case, so I won't worry about the time either.
Is there a way to read a bundle from onResume(), should I just implement a shared preference?
I'd like to avoid updating the elapsed time in the game loop as this seems inefficient.

I would advice not using a SharedPreference at all.
You will only need 2 fields: startTime and elapsedTime
When the player starts, initialise elapsedTime to 0 and startTime to System.currentTimeMillis()
When onPause() is called, initialise elapsedTime using
elapsedTime = elapsedTime + (System.currentTimeMillis() - startTime);
When onResume() is called, initialise startTime to System.currentTimeMillis()
When the player is done, the time is
elapsedTime = elapsedTime + (System.currentTimeMillis() - startTime);
Please, if the logic has a flaw, comment (:
Note: There exists a way to use only one field.! But we'll keep that for the reader to discover.

shared preference seems a better idea to me.
calculate the time difference in onPause() , when the game goes to background, assuming user is already playing game. Add this difference to the previous time in the shared preference and store it again.
start the clock again on onResume() and repeat step 1 if necessary.
I hope you get the idea.