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;
}
Related
I have a datepicker on my android studio app. The data has successfully shown as date, but in firebase it became a random number. This is my code
Calendar calendar = Calendar.getInstance();
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd-MMMM-YYYY");
Date date_minimal;
Date date_maximal;
DatePickerDialog datePickerDialog = new DatePickerDialog(context, new DatePickerDialog.OnDateSetListener() {
#Override
public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
calendar.set(year, month, dayOfMonth);
tgl_daftar.setText(simpleDateFormat.format(calendar.getTime()));
tgl_daftar_date = calendar.getTime();
database.child("user").push().setValue(new dataUser(
nama,
radioButton.getText().toString(),
jurusan,
tgl_daftar_date.getTime()
When input the data, the date came out as a date like this.
screenshot of data in app
But in firebase, it became like this.
screenshot of firebase
I want it to display as a date too in firebase. How do i fix this? Thank you
You're call tgl_daftar_date.getTime() to store the Date object. This method is documented as:
returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this Date object.
So the number that is stored is the number of milliseconds since January 1, 1970, often also referred to as the epoch. This is a very common format to store timestamps in, especially in databases that (like Firebase's Realtime Database) cannot store Java's Date objects natively.
If you store a Date/timestamp right now, the value will be:
console.log(Date.now())
To convert the value from the database back to a Java Date object, see How to convert currentTimeMillis to a date in Java?
I want to compare time difference in hours. Based on current time and time I get from database.
DateFormat sdf = new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss”);
Date date = new Date();
Logger.info(“current time is”,sdf.format(date));
// gives date in 2019-11-06 17:03:54
// dB gives following record
Date successDate = loader.getLastSuccess();
// gives date in 2019-10-31T:56:08.066+0000
Both formats are different how to get the time difference any suggestion experts
You can use the java-8 date API Duration to get the duration between both the dates
long hours = Duration.between(date1.toInstant(), date2.toInstant()).toHours();
Note : It can return negative value also here
the number of hours in the duration, may be negative
public int getHours() on util.Date is deprecated, so convert them to Instant and use Duration.between and also i will suggest to use java-8 Date API instead of older version Date
If you want difference in hours as double, you can do this;
Date your_date = loader.getLastSuccess();
Date currentDate = new Date();
double hourdifference = (currentDate.getTime() - your_date.getTime()) / 3600000.0;
You can get long or int, just change 3600000.0 to 3600000, and make the variable int or long
This question already has answers here:
Java Calendar adds a random number of milliseconds?
(4 answers)
Closed 4 years ago.
I'm wondering why I always get a difference between this date in milliseconds.
Any idea ?
Here is the output :
date = 1572794103293 ms
date2 = 1572794103341 ms
date3 = 1572794103341 ms
date4 = 1572794103341 ms
and here is the code :
Date date = createDate();
Date date2 = createDate();
Date date3 = createDate();
Date date4 = createDate();
System.out.println(date.getTime());
System.out.println(date2.getTime());
System.out.println(date3.getTime());
System.out.println(date4.getTime());
private static Date createDate() {
Calendar c = GregorianCalendar.getInstance();
c.set(2019, Calendar.NOVEMBER, 03, 16, 15, 03);
return c.getTime();
}
In the documentation of Calendar.set, it is said :
Sets the values for the fields YEAR, MONTH, DAY_OF_MONTH, HOUR, MINUTE, and SECOND. Previous values of other fields are retained. If this is not desired, call clear() first.
The reason is that not all fields are set with this method, in you case, you don't have MILLISECOND set. So it keep the value when the instance was created.
The call of Calendar.clear will
Sets all the calendar field values and the time value (millisecond offset from the Epoch) of this Calendar undefined.
A quick example :
Calendar c = GregorianCalendar.getInstance();
c.clear();
c.set(2019, Calendar.NOVEMBER, 03, 16, 15, 03);
System.out.println(c.getTimeInMillis());
1572794103000
Milliseconds being undefined will give 0
In addition to the comments and AxelH's answer mentioning the fact that the milliseconds of a Calendar instance aren't changed by Calendar.set, there is still the curiosity that you get the same value for date2, date3 and date4, but a different value for date.
This is because the very first time you call createDate() the JVM has to initialize the Date class, which happens after Calendar c was initialized.
Thus on the first call c.getTime() needs more time than on the consecutive calls, which you can see as the difference between the value of date and the other 3 instances.
If you add a call to new Date() before the first call to createDate(), the difference between each value should be the same.
Please note that this does not fix your issue, it just hides it if your machine is fast enough. It's merely an explanation for the particular values you get.
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();
The date is selected by the user using a drop down for year, month and day. I have to compare the user entered date with today's date. Basically see if they are the same date. For example
the user entered 02/16/2012. And if today is 02/16/2012 then I have to display a message. How do I do it?
I tried using milliseconds but that gives out wrong results.
And what kind of object are you getting back? String, Calendar, Date? You can get that string and compare it, at least that you think you'll have problems with order YYYY MM DD /// DD MM YYY in that case I suggest to create a custom string based on your spec YYYYMMDD and then compare them.
Date d1 = new Date();
Date d2 = new Date();
String day1 = d1.getYear()+"/"+d1.getMonth()+"/"+d1.getDate();
String day2 = d2.getYear()+"/"+d2.getMonth()+"/"+d2.getDate();
if(day1.equals(day2)){
System.out.println("Same day");
}
Dates in java are moments in time, with a resolution of "to the millisecond". To compare two dates effectively, you need to first set both dates to the "same time" in hours, minutes, seconds, and milliseconds. All of the "setTime" methods in a java.util.Date are depricated, because they don't function correctly for the internationalization and localization concerns.
To "fix" this, a new class was introduced GregorianCalendar
GregorianCalendar cal1 = new GregorianCalendar(2012, 11, 17);
GregorianCalendar cal2 = new GregorianCalendar(2012, 11, 17);
return cal1.equals(cal2); // will return true
The reason that GregorianCalendar works is related to the hours, minutes, seconds, and milliseconds being initialized to zero in the year, month, day constructor. You can attempt to approximate such with java.util.Date by using deprecated methods like setHours(0); however, eventually this will fail due to a lack of setMillis(0). This means that to use the Date format, you need to grab the milliseconds and perform some integer math to set the milliseconds to zero.
date1.setHours(0);
date1.setMinutes(0);
date1.setSeconds(0);
date1.setTime((date1.getTime() / 1000L) * 1000L);
date2.setHours(0);
date2.setMinutes(0);
date2.setSeconds(0);
date2.setTime((date2.getTime() / 1000L) * 1000L);
return date1.equals(date2); // now should do a calendar date only match
Trust me, just use the Calendar / GregorianCalendar class, it's the way forward (until Java adopts something more sophisticated, like joda time.
There is two way you can do it. first one is format both the date in same date format or handle date in string format.
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
String date1 = sdf.format(selectedDate);
String date2 = sdf.format(compareDate);
if(date1.equals(date2)){
}else{
}
Or
Calendar toDate = Calendar.getInstance();
Calendar nowDate = Calendar.getInstance();
toDate.set(<set-year>,<set-month>,<set-date->);
if(!toDate.before(nowDate))
//display your report
else
// don't display the report
Above answers are correct but consider using JodaTime - its much simpler and intuitive API.
You could set DateTime using with* methods and compare them.
Look at this answer