I hope someone can help. Im trying to set up a timer that times from the start of a game and displays this time. The problem is that the following section of code gives me the wrong time. Its in the wrong format, and is out by an hour.
private long startTime;
private SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm:ss.SS");
//Constructor:
startTime = System.currentTimeMillis();
public String getTime() {
long gameTime = System.currentTimeMillis() - startTime;
final Date date = new Date(gameTime);
return timeFormat.format(date);
}
It consistently gives me the output of 01:00:03:203. The seconds are correct, but the 1 hour shouldn't be there, and for format is 3 decimal places instead of the two I thought I specified.
Thank you very much!
Your date is epoch + gameTime. I think you're experiencing a daylight saving shift since the current DST in your location today doesn't match the DST at epoch.
Use a Calendar instead of a Date. Start with today and explicitly wipe out the hour, minute, etc. parts:
Calendar cal = Calendar.getInstance();
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 3600000 + 60000 + 1000 + 1);
SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm:ss.SS");
System.out.println(timeFormat.format(cal.getTime()));
The output for the above is: 01:01:01.01
http://ideone.com/DyQcl
Substitute the numbers I have above with gameTime and you're done.
Of course, this may not work once your millisecond ticks exceed the day boundary.
Related
I have a string that may contain value 07:00 or 11:00 0r 15:00
I want to set alarm for that time for today. it doesn't seem to work
One option is to create a calendar object set to midnight, and then offset it by the hours and minutes you have:
String alarm = "13:00";
Calendar c = new GregorianCalendar();
c.set(Calendar.HOUR_OF_DAY, 0);
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 0);
long millis = c.getTime().getTime();
millis += 1000*60*60*Integer.parseInt(alarm.substring(0, 2));
millis += 1000*60*Integer.parseInt(alarm.substring(3, 5));
Demo
An alternative to this would be to use two SimpleDateFormat masks to parse out the timestamp you want.
so I have this code in Android
DateFormat formatter = new SimpleDateFormat("HH:mm", Locale.getDefault());
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(millisUntilFinished);
textView.setText(formatter.format(calendar.getTime()));
here is how I am passing the values to this method, where the hours and minutes strings are "8" and "30" for example
Calendar c = Calendar.getInstance();
String s = ApplicationPreferences.getWakeUp(ActivityStage1.this);
String[] separated = s.split("\\:");
String hours = separated[0];
String minutes = separated[1];
c.add(Calendar.DAY_OF_MONTH, 1);
c.set(Calendar.HOUR_OF_DAY, Integer.parseInt(hours));
c.set(Calendar.MINUTE, Integer.parseInt(minutes));
c.set(Calendar.SECOND, 0);
c.set(Calendar.MILLISECOND, 0);
long timeUntilStageTwo = (c.getTimeInMillis() - System.currentTimeMillis());
startStageTwoTimer(timeUntilStageTwo);
So the value in the long millisUntilFinished is something like 58441666, which is around 16 hours and 20 min, but for some reason the time it shows at the end in the text view is with 3 hours more, I even tried with different locales passed to SimpleDateFormat, and still the same, why is that happening?
Your Calendar c is in your local UTC+3 timezone while the system clock runs at UTC. Hence the difference of 3 hours.
You can use setTimeZone() to set an explicit timezone on your calendar before computing its millisecond value.
If you prefer to do the computations yourself, you can get the user's timezone with TimeZone.getDefault() and then use getOffset(time) to get the millisecond offset at specified UTC time.
I am using following code to convert timezone (GMT-3) to device local timezone.
int hour=17,minute=0,day=12,month=6,year=2014;
Calendar cal = new GregorianCalendar(TimeZone.getTimeZone("GMT-3"));
cal.set(year, (month-1), day,hour,minute);
cal.setTimeZone(TimeZone.getDefault());
Log.d("Time", cal.get(Calendar.DATE)+"/"+cal.get(Calendar.MONTH)+"/"+cal.get(Calendar.YEAR)+" , "+cal.get(Calendar.HOUR_OF_DAY)+":"+cal.get(Calendar.MINUTE)+" "+cal.get(Calendar.AM_PM));
My local timezone is GMT+5:30
Expected result is
Time 13/5/2014, 1:30 0
But I am getting the result
12/5/2014 , 13:30 1
Sorry for you, GregorianCalendar is sometimes the hell. Your problem is following:
If you immediately set the timezone after having set the fields for year, month etc. then this mutable calendar class will only shift the timezone retaining the already set fields containing the local time. Those fields for year, month etc. will NOT be recalculated. This behaviour causes a shift on the global timeline represented by cal.getTime(), too.
In order to force the calendar object to recalculate the fields you need to call a getter. Watch out for following code and especially remove the comment marks to see the effect.
int hour = 17, minute = 0, day = 12, month = 6, year = 2014;
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mmZ");
TimeZone tz1 = TimeZone.getTimeZone("GMT-3");
sdf.setTimeZone(tz1);
Calendar cal = new GregorianCalendar(tz1);
cal.set(year, (month - 1), day, hour, minute);
// System.out.println(sdf.format(cal.getTime()));
// System.out.println("Hour=" + cal.get(Calendar.HOUR_OF_DAY));
TimeZone tz2 = TimeZone.getTimeZone("GMT+0530");
sdf.setTimeZone(tz2);
cal.setTimeZone(tz2);
System.out.println(sdf.format(cal.getTime()));
System.out.println("Hour=" + cal.get(Calendar.HOUR_OF_DAY));
Output with comment-disabled lines:
2014-06-12T17:00+0530
Hour=17
Output with enabled lines after having removed the comment marks:
2014-06-12T17:00-0300
Hour=17
2014-06-13T01:30+0530
Hour=1
I would like to get the current date with the time zeroed out in milliseconds.
Example, if it's 12:69pm today, I want to get the time in milliseconds for today's date with no time...meaning, the time just after midnight (one millisecond or 0 if that works).
I was using the Calendar object but can't seem to figure out how to zero out the time portion.
Here is how to zero the time of a calendar:
Calendar today = Calendar.getInstance();
today.set(Calendar.MILLISECOND, 0);
today.set(Calendar.SECOND, 0);
today.set(Calendar.MINUTE, 0);
today.set(Calendar.HOUR_OF_DAY, 0);
And without calendar:
long d = new Date().getTime();
int offset = TimeZone.getDefault().getOffset(d);
d = ((d + offset)/ 86400000l) * 86400000l - offset;
I have read all of the docs and there doesnt seem to be too much to really explains the date functions, or the lack there of.
I am trying implement the AlarmManger which needs the time in milliseconds (ms) for the trigger. To test I took the current time and added 5 seconds and that was good.
// get a Calendar object with current time
Calendar cal = Calendar.getInstance();
// add 5 minutes to the calendar object
cal.add(Calendar.SECOND, 5);
If I have a date and time how would I get the ms for that time.
Like "3/2/2011 08:15:00"
How do I turn that into milliseconds?
Use this method.
example:
method call for 3/2/2011 08:15:00
D2MS( 3, 2, 2011, 8, 15, 0);
method
public long D2MS(int month, int day, int year, int hour, int minute, int seconds) {
Calendar c = Calendar.getInstance();
c.set(year, month, day, hour, minute, seconds);
return c.getTimeInMillis();
}
When using AlarmManager you have two choices in setting an alarm - the first is time in ms since device reboot (don't understand that option) or, if you want an 'absolute' time, then you need to provide a UTC time in ms.
I think this should work - I've done something similar in the past...
public long getUtcTimeInMillis(String datetime) {
SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
Date date = sdf.parse(datetime);
// getInstance() provides TZ info which can be used to adjust to UTC
Calendar cal = Calendar.getInstance();
cal.setTime(date);
// Get timezone offset then use it to adjust the return value
int offset = cal.getTimeZone().getOffset(cal.getTimeInMillis());
return cal.getTimeInMillis() + offset;
}
Personally I'd recommend trying to use a non-localised format such as yyyy-MM-dd HH:mm:ss for any date/time string you use if you want to cater for users globally.
The ISO 8601 international standard is yyyy-MM-dd HH:mm:ss.SSSZ but I don't normally go that far.