Develop Reference

CalendarView show minimum date as today

I want to show calendarView that will set the minimum date as today for booking purposes. But in my code it will show the whole month and here I can book the previous date. So, I need a solution that will show dates available from today and can not select previous days.
How can I do this?
My code:
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.DATE,Calendar.getInstance().getActualMinimum(Calendar.DATE));
long date = calendar.getTime().getTime();
calendar_view.setMinDate(date);

Here is a solution. You need to set current date to the calendar minimum date.
Calendar calendar = Calendar.getInstance();
mCalendarView.setMinDate(calendar.getTimeInMillis());

Week type in different countries

There are some countries which first day of week begin on Sunday, instead other countries like mine begin on Monday. Is there any way to know which calendar is used in the country of the user.
I'm developing an application in Android with a calendar and I don't know how to solve this problem.

Set your country timeZone in Calendar class.
Calendar cal = Calendar.getInstance();
TimeZone tz = TimeZone.getTimeZone("GMT");
cal.setTimeZone(tz);
or
you can add the offset by if using UTC date or time.

Compare current date with stored one

For an easteregg in my Android app, I have to compare the current date with a stored date - and I only need to know if it's the right month.
I know that System.currentTimeMillis() is the fastest way to get the current time but now I need to get the current month from that. I avoided String comparison for it's known flaws.
My awful implementation works but it really doesn't look correct and efficient:
if (Integer.parseInt((String) DateFormat.format("MM",System.currentTimeMillis()))==12) //xmas "easteregg"
xmasBool=true;
Is there any more elegant solution for this?

Here's a better solution:
Calendar calendar = Calendar.getInstance();
calendar.setTime(new Date()); // Date's default constructor gives you current time
xmasBool = calendar.get(Calendar.MONTH) == Calendar.DECEMBER;

Calendar c = Calendar.getInstance();
int month = c.get(Calendar.MONTH);
And now you can compare the variable month with your stored month.

You can compare a day or a month or both, the whole date by formatting java.Util.Date using SimpleDateFormat.
Eg.
new SimpleDateFormat("dd").format(new java.util.Date())
gives you the "day" value. Similarly "MM" will give you the month. Use combination of those as per your requirement.
Store it in the same format and you have a common standard for comparison.

Convert date into time I am getting wrong value in android

I am converting date to time, and I have a problem with minimum date and maximum date.
The minimum date time value is higher than the maximum date time value. I don't know how it is happening. Please help me understand why it is happened.
here i pass the values coming from the date picker when i select the march month 31st date 2014 year.
Date date, minPdate, maxPdate;
SimpleDateFormat sdf = new SimpleDateFormat("dd.MM.yyyy");
try {
date = sdf.parse(someDate);
minPdate = sdf.parse("31.02.2014");
maxPdate = sdf.parse("01.03.2014");
lmin = minPdate.getTime();
lmax = maxPdate.getTime();
Log.v("tag","min date "+lmin);
Log.v("tag","max date "+lmax);
} catch (ParseException e) {
e.printStackTrace();
}
Minimum date is March-31-2014 and Maximum date is April-01-2014.
And my result is
min date 1393804800000
max date 1393632000000

You have a wrong date in minDate:
31.02.2014 is invalid date.
try with 28.02.2014.
It seems the long value for 31st feb is treated as 3rd march.
So the long value of 1st march is less than 3rd march.

Java calendar/date APIs are generally considered (by me at least) horrible. As said, 31st feb is being treated as 3rd of march.
However, since you're using Android's DatePicker API, and you seem to want the milliseconds since epoch, you should probably use datePicker.getCalendarView().getDate(). However it might be possible that this is not available and you should just accept the fact that sometimes in java date related APIs month indexing starts with a 0 and sometimes in other classes it starts with 1.
Apparently DatePicker is modeled after Java's Calendar API, which uses 0-based indexing for months. So really you should be using a Calendar object to handle the data.
Calendar cal = new Calendar();
cal.set(datePicker.getYear(), datePicker.getMonth(), datePicker.getDayOfMonth());
Log.d("tag", "time in millis " + cal.getTimeInMillis());
if you want a Date you can just use cal.getTime()

Converting milliseconds to Date object

I am having following code to convert milliseconds to Android Date object.
Date dateObj = new Date(milli);
But problem is that my milliseconds value is having GMT value added in it before i pass it to Date class, add when i print this date object i can see that date object is again adding GMT value in the milliseconds value and because of that my date is displayed as wrong.
So how can i generate Date object with out considering GMT value in it.
For example my milliseconds are 1385569800000 which is getting printed as below:
Wed, 27 Nov 2013 22:00:00 --> +5.30
But the current value of this time stamp without adding GMT is:
Wed, 27 Nov 2013 16:30:00
*UPDAE*
It is not just about printing the date in right format and with right date time.
But i want to use that date object to schedule TimeTask.
So basically i want to create Date object which has proper date time value in it with out adding extra GMT time added in it.

A Date is always in UTC. No need to change that.
When printing the date value, use SimpleDateFormat and call setTimeZone() on it before formatting the output string.
It is not just about printing the date in right format and with right date time.
But i want to use that date object to schedule TimeTask.
TimerTask is just a task and not its scheduling. Timer accepts a Date object for scheduling. The Date is in UTC there as well.

try my code if you a
long currentTime = System.currentTimeMillis();
TimeZone tz = TimeZone.getDefault();
Calendar cal = GregorianCalendar.getInstance(tz);
int offsetInMillis = tz.getOffset(cal.getTimeInMillis());
currentTime -= offsetInMillis;
Date date = new Date(currentTime);
it is work for me

You can try with joda-time API.
Joda-Time provides a quality replacement for the Java date and time classes. The design allows for multiple calendar systems, while still providing a simple API. The 'default' calendar is the ISO8601 standard which is used by XML. The Gregorian, Julian, Buddhist, Coptic, Ethiopic and Islamic systems are also included, and we welcome further additions. Supporting classes include time zone, duration, format and parsing.
http://joda-time.sourceforge.net/key_instant.html

A Date object simply represents a moment in time. Imagine you're on the phone to someone on a different continent, and you say "3...2...1...NOW!". That "NOW" is the same moment for both of you, even though for one person it's 9am and for the other it's 4pm.
You're creating a Date representing the moment 1385569800000 milliseconds after the Java epoch (the beginning of 1970, GMT). That is your "NOW", and it's fixed and unchanging. What it looks like converted into text, however, depends on which timezone you want to display it for. Java defaults to using GMT, which would be right if you were in Britain during the winter, but for (I'm guessing) India you want it in a different time zone. Laalto's answer shows you how to do that.

here is the code,that worked like charm for me:
public static String getDate(long milliSeconds, String dateFormat)
{
// Create a DateFormatter object for displaying date in specified format.
DateFormat formatter = new SimpleDateFormat(dateFormat);
// Create a calendar object that will convert the date and time value in milliseconds to date.
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(milliSeconds);
return formatter.format(calendar.getTime());
}