We Keep Coding

Setting maximum date and minimum date to CalendarView in Android C#

I am trying to set the minimum date of a calendarview object on an alarm application I am building in Rider to today.
I add seven days to the datetime object and then assign the milliseconds property of that object as the maximum date to the calendarview, but the calendar shows up with the year 1970 and date 1 o January enabled. The rest of the days are disabled. Why is this happening as the code am using seems to be logically correct?
void Setup()
{
//get the current date from the system
DateTime today= DateTime.Today;
//get the time in millis
//set the calendarview minimum date to this
mycalendar.MinDate = today.Millisecond;
//add seven days
DateTime addseven =today.AddDays(7);
//set the maximum date on the calendar
mycalendar.MaxDate = addseven.Millisecond;
}

I figured it out on my own using the Calendar class of Android Java. Just get an instance and assign the millisecond property of that instance to the minimum date and then add seven days to the instance using CalendarField.Date as type of adjustment like below
void Setup()
{
Calendar calendar = Calendar.Instance;
mycalendar.MinDate = calendar.TimeInMillis;
//add seven days to the time
calendar.Add(CalendarField.Date,7);
//assign the new time to the maximum
mycalendar.MaxDate = calendar.TimeInMillis;
}

Parse Date String Return Wrong Month

I try to parse date string but always get wrong month. Here's my code.
This is code to select date from calender
#OnClick(R.id.tedit_tgllahir_addnew) void showTimeDialog(){
calendar = Calendar.getInstance();
year = calendar.get(Calendar.YEAR);
month = calendar.get(Calendar.MONTH);
date = calendar.get(Calendar.DAY_OF_MONTH);
DatePickerDialog datePickerDialog = new DatePickerDialog(AddDataForNewUserActivity.this,
new DatePickerDialog.OnDateSetListener() {
#Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
etTgl.setText(String.format("%02d/%02d/%02d", year, month+1, dayOfMonth));
}
}, year, month, date);
datePickerDialog.show();
}
and this is when i want to parse data
birth = LocalDate.of(list.getTglLahirAnak().getYear() + 1900, list.getTglLahirAnak().getMonth(), list.getTglLahirAnak().getDate());
int year = Period.between(birth, LocalDate.now()).getYears();
int month = Period.between(birth, LocalDate.now()).getMonths();
int totalBulan = year * 12 + month;
Whenever I input date from the calender, it always shows the wrong month. For example I choose May but in the system read April. Thanks to all who are willing to help.

I gather from your question that you are using the backport of JSR-310, probably the Android edition, ThreeTenABP. If so, go all-in on that and drop the use of the poorly designed and long outdated Calendar and Date classes.
Even if the use of the Date class is dictated from outside of your control, you must still stay away from its deprecated methods including getYear(), getMonth() and getDate(). You are trying the good thing when receiving a Date and converting it to a LocalDate first thing. Use DateTimeUtils from the backport for a first conversion.
But let’s take it from the top. Use LocalDate for setting the initial date of your date picker. Don’t use the old-fashioned Calendar class. I have not compiled the code, so please forgive if there’s a typo.
LocalDate today = LocalDate.now(ZoneId.systemDefault());
year = today.getYear();
month = today.getMonthValue(); // naturally 1-based
date = today.getDayOfMonth();
DatePickerDialog datePickerDialog = new DatePickerDialog(AddDataForNewUserActivity.this,
new DatePickerDialog.OnDateSetListener() {
#Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
// will return to this part later
}
}, year, month - 1, date); // Pass 0-based month
When the user selects a date from the calendar/date picker, don’t store it as a string. Store it as a LocalDate object. This saves you from doing any parsing later, and your code also shows that you need a LocalDate. Obviously if you want to show the selected date to the user, format the date into a string for that purpose (only). Use a DateTimeFormatter for formatting:
private static final DateTimeFormatter dateFormatter
= DateTimeFormatter.ofPattern("yy/MM/dd");
Now we go:
#Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
// Store the selected date somewhere you can find it later
selectedLocalDate = LocalDate.of(year, month + 1, dayOfMonth);
// Display to the user
String formattedDate = selectedLocalDate.format(dateFormatter);
etTgl.setText(formattedDate);
}
Now the calculation of age in months poses no problem anymore:
birth = selectedLocalDate;
long totalBulan = Period.between(birth, LocalDate.now(ZoneId.systemDefault()))
.toTotalMonths();
If you cannot control what you get from list.getTglLahirAnak(), the conversion from Date to LocalDate is:
Date oldfashionedDate = list.getTglLahirAnak();
birth = DateTimeUtils.toInstant(oldfashionedDate)
.atZone(ZoneId.systemDefault())
.toLocalDate();
Now the calculation of age proceeds as before.
What went wrong in your code?
Just like the outdated Calendar also the deprecated Date.getMonth() numbers the months from 0 for January through 11 for December. So if you pick a date in May, list.getTglLahirAnak().getMonth() returns 4 for May. When you feed this into a LocalDate with its natural and sensible month numbering, it gives you April.

get yesterday date from timestamp [duplicate]

This question already has answers here:
Get yesterday's date using Date [duplicate]
(8 answers)
Closed 8 years ago.
I've got an object with a field timestamp with type java.sql.Timestamp;.
And I need to get objects with yesterday date from a collection.
How to get them?
I mean I need something like this
for(int i = 0; i < items.size(); i++) {
(if the items.get(i).date == yesterday_date)
(get object)
}

You can get yesterday's Date by following approach Answered by Jiger Joshi.
And by using new Timestamp(java.util.Date) you can get yesterday's timestamp, you should use Timestamp#equals to equaling two different timestamp.
if (items.get(i).date.equals(getYesterdaytimestamp())){
...
}
And there are something which you must consider while implementing this. Calender#getTime which returns Date object and date object contains date with time, so in that case your equaling date or timestamp must be exactly equals with yesterday's date and time.
If requirement is, it needs to equal just yesterday no not where time is not considerable fact. In that case you need to equals two timestamp after discarding time part.
if (equalsWithYesterday(items.get(i).date)){
...
}
...
public boolean equalsWithYesterday(Timestamp st){
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd"); // Time part has discarded
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
Date yesterday = dateFormat.parse(dateFormat.format(cal.getTime())); // get yesterday's Date without time part
Date srcDate = new Date(st);
Date srcDateWithoutTime =dateFormat.parse(dateFormat.format(srcDate));
return yesterday.equals(srcDateWithoutTime ); // checks src date equals yesterday.
}

You can convert the timestamp object to date object like this:
Date date = new Date(items.get(i).getTime());
or you can simply use method Timestamp#compareTo(Date o)
items.get(i).compareTo(yesterday_date);

I hope you are not interested to compare the time?
Simply use Calendar class to extract the day, month, year etc. from the date and simply compare it.
Use Calendar#get() method to get the specific field from the date object.
How to subtract one day from the current date?
// get Calendar with current date
Calendar cal = Calendar.getInstance();
// get yesterday's date
cal.add(Calendar.DATE, -1);
// get components of yesterday's date
int month = cal.get(Calendar.MONTH) + 1; // 0 for January, 1 for Feb and so on
int day = cal.get(Calendar.DATE);
int year = cal.get(Calendar.YEAR);
// get yesterday's date in milliseconds
long lMillis = cal.getTime().getTime();

Problems with the Date 31-12-9999 in java

My program needs to represent this date as a java.sql.date object , but it seems that when I create a new date (using the calendar) and set it to '9999-12-31' and finally convert this java.util.date object to a java.sql.date object, this date is converted to something like '000-01-31'.
Calendar calendar = Calendar.getInstance();
calendar.set(9999, 12, 31);
infinityDate = new java.sql.Date(normalizeDate(calendar.getTime()).getTime());
infinityDate should be 31-12-9999
but when my code reaches here :
if(otherDate.equals(infinityDate))
{// Do stuff}
It never goes into the if condition as the infinityDate has for some reason been changed to 31-01-000, even though otherDate is infact '31-12-9999'.
The fact that otherDate is 31-12-9999 tells me that java can represent this dates , but for some reason , when I construct it using a calendar it changes the date. (otherDate comes from a jdbc statement which fetches data from a database)
This reference date '31-12-9999' has been fixed by some client , so it cannot be changed and my program has to be able to compare some incoming date values with this.
Does anyone know why this is happening , I realize that http://en.wikipedia.org/wiki/Year_10,000_problem may be a problem for dates after year 9999 , but I should be safe by a day.
EDIT : The Normalize date method only "normalizes the given date to midnight of that day"
private static java.util.Date normalizeDate(java.util.Date date) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.set(Calendar.HOUR_OF_DAY, 0);
calendar.set(Calendar.MINUTE, 0);
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);
date = calendar.getTime();
return date;
}
But , this issue was appearing before I was normalizing the date , I normalized it in an attempt to fix this.

Months are zero indexed. Use 11 for December, not 12. This is why you are rolling over the year.

Calendar.MONTH is zero-based. The call
calendar.set(9999, 12, 31);
sets the date to "the 31st day in the 13th month of the year 9999", which is then implicitly converted to the 1st month of the year 10000. It would result in an exception if you first called
calendar.setLenient(false);

Check hours, minutes, seconds and milliseconds that are held into these 2 date objects. I believe they are different.
If your want to compare the date (year, month, day) only you should probably create your custom Comparator and use it.

Android java datetime values from String to Long to String issue

Long time reader, first time poster.
In Android, capturing date from datepicker and storing as string in sqlite. Sorting by date doesn't work because they're strings (unless I'm doing it wrong.
I've googled this issue for ~5 days, and it looks like there should be a way to capture the date from the date picker, convert it to a Long, store it in sqlite as a Long, select and sort on the Long date value, then convert the Long back to a "mm/dd/yyyy" string for display. I've tried various combinations of parse statements, Date, FormatDate, etc. with no luck at all.
My actual application flow would be:
On activity start, get today's date and display it in button which calls the datepicker.
Capture new date from datepicker (if one is entered), save it as a long to sqlite.
On opening an activity showing a listview of records, select from sqlite with orderby on date (Long), convert Long to "mm/dd/yyyy" string for display in ListView.
If someone could point me at a code sample, it would be greatly appreciated - thanks!
Evan

Hours of hair-pulling later, the solution is sort of a mix of the answers given, and some other things:
// variables declared
private int mYear;
private int mMonth;
private int mDay;
// datepicker declared and listened for
private DatePickerDialog.OnDateSetListener mDateSetListener = new DatePickerDialog.OnDateSetListener() {
public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
mYear = year;
mMonth = monthOfYear;
mDay = dayOfMonth;
updateDisplay();
}
};
// converting the datestring from the picker to a long:
Calendar c = Calendar.getInstance();
c.set(Calendar.DAY_OF_MONTH, mDay);
c.set(Calendar.MONTH, mMonth);
c.set(Calendar.YEAR, mYear);
Long lDate = c.getTime().getTime();
//The formatting that worked on the trip back from long to string
// (I spent hours with SimpleDateFormat strings, years that were off by 1500, etc.):
String DateFormatted = DateFormat.getDateFormat(getApplicationContext()).format(helper.getDate(c)); // helper.getDate(c) is just the passing back of the Long date from my SELECT statement
New to the forum - I tried to vote up as useful, but I don't have enough reputation points yet.

All Date objects in java are just Long values behind the scenes. You can get the Long value from a java Date object using getTime(), storing the resulting long value, and then initializing a new Date object using that long value in the constructor. Since the DatePicker gives interfaces to Day, Month and Year you should use the java Calendar class as an interim by creating a new Calendar object, setting the day, month and year before extracting a Date object and then a long value from the Date object.
I would say something along these lines:
DatePicker dp = blah blah;
Calendar c = Calendar.getInstance();
c.set(Calendar.DAY_OF_MONTH, dp.getDayOfMonth());
c.set(Calendar.MONTH, dp.getMonth());;
c.set(Calendar.YEAR, dp.getYear());
long l = c.getTime().getTime();
From here you can serialize your long value. Obviously then to reverse the process you pull the long value out, construct a Date object with the long value and then use a Calendar.setTime(Date) call before using the Calendar.get function to get the values to use on the DatePicker.init function, or utilizing a SimpleDateFormat object to get it prepped for display in a format like you described.

I'd just use a date as I think Calendar objects are a bit heavy for this task. Get your values from your DatePicker :
public void onDateSet(DatePicker view, int year,
int monthOfYear, int dayOfMonth) {
mYear = year;
mMonth = monthOfYear;
mDay = dayOfMonth;
updateDisplay();
}
Use the integers provide to the DatePicker to create a Date:
Date date = new Date(mYear, mMonth, mDay);
Then store and sort by the long value : date.getTime().
Alternatively, if you really must use strings for sorting dates, format them in yyyy/mm/dd format to ensure proper sorting, even then you need to watch out. I've just done some tests with SimpleDateFormat and it parses inappropriate date strings e.g. 2010/09/31 is interpreted as 2010/10/01.
When checking stuff like this I would always recommend running up some JUnit tests.