I have two functions which convert a date String to a date in milliseconds:
public static long convertYYYYMMDDtoLong(String date) throws ParseException {
SimpleDateFormat f = new SimpleDateFormat("yyyy-mm-dd");
Date d = f.parse(date);
long milliseconds = d.getTime();
return milliseconds;
}
If I run this function I get the following result:
long timeStamp = convertYYYYMMDDtoLong("2014-02-17");
System.out.println(timeStamp);
It prints:
1389909720000
Now, if I run the following code:
Calendar cal = Calendar.getInstance();
cal.setTimeInMillis(timeStamp);
System.out.println(cal.getTime());
It prints out:
Fri Jan 17 00:02:00 IST 2014
Why is my date shifted by one month? What is wrong?
P.S: My problem is that I need to map the date, represented as long, to another third party API which accepts Calendar format only.
You're using mm, which is minutes, not months. You want yyyy-MM-dd as your format string.
It's not clear why you're not returning a Calendar directly from your method, mind you:
private static final TimeZone UTC = TimeZone.getTimeZone("Etc/UTC")
public static Calendar convertYYYYMMDDtoCalendar(String text) throws ParseException {
DateFormat format = new SimpleDateFormat("yyyy-MM-dd", Locale.US);
format.setTimeZone(UTC);
Calendar calendar = new GregorianCalendar(UTC);
calendar.setDate(format.parse(text));
return calendar;
}
(That's assuming you want a time zone of UTC... you'll need to decide that for yourself.)
Related
below is the code I have used to add the number of days to the existing date..which gave me string output and I want that to be converted to Date format again...I have tried formating but it gave the out put -->
Date date = sdf.parse(dt);
sysout (date ) --giving me -- Mon May 05 00:00:00 PDT 2008
but I want it as YYYY-MM/DD
sdf.format(date) --Gives me 2008-05-05 which I am looking but it is a string object...but I want this to be converted to DATE type
String dt = "2008-01-01"; // Start date
System.out.println("start date "+dt);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Calendar c = Calendar.getInstance();
c.setTime(sdf.parse(dt));
c.add(Calendar.DATE, 125); // number of days to add
dt = sdf.format(c.getTime());
System.out.println("c.getTime() "+c.getTime());
System.out.println("end date "+dt);
Date date = sdf.parse(dt);
System.out.println("last but one date in DATE form -->" +date);
System.out.println("last formatted date in string form "+sdf.format(date));
You created the format right.
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
but you are using it incorrectly. you should use
sdf.format(your_unformated_date);
Here is a sample code that will convert date from String to Date type using SimpleDateFormat Class:
public static void convert()
{
String str="10:25:35";
SimpleDateFormat sdf=new SimpleDateFormat("hh:mm:ss");
System.out.println(sdf.format(str));
}
Where is some function to get the last day of month in my service?
DateFormat format = new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH);
Date date = format.parse(stringDate);
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.add(Calendar.MONTH, 1);
calendar.set(Calendar.DAY_OF_MONTH, 1);
calendar.add(Calendar.DATE, -1);
Date lastDayOfMonth = calendar.getTime();
DateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
return sdf.format(lastDayOfMonth);
So, this method correctly works elsewhere, but in US last day is always 29 (last day - 1)
stringDate is date in format "yyyy-MM-dd"
I believe this problem is due to Day Light saving time in US.
You can change this by setting the Timezone for Calendar to different timezone.
Related question: Adding days with java.util.Calendar gives strange results
Java Date has very poor API. Instead of this I would recommend you to use Joda Time.
In Joda it would look like this:
LocalDate endOfMonth = date.dayOfMonth().withMaximumValue();
If you don't have Java 8, this is very compact with JodaTime.
import org.joda.time.DateTime;
public class SoLastDay {
public DateTime lastDay(final String yyyy_MM_dd) {
DateTime givenDate = new DateTime(yyyy_MM_dd);
return givenDate.dayOfMonth().withMaximumValue();
}
}
And a small test...
#Test
public void testLastDay() throws Exception {
SoLastDay soLastDay = new SoLastDay();
String date1 = "2015-01-27";
System.out.printf("Date %s becomes %s.\n", date1, soLastDay.lastDay(date1).toString("yyyy-MM-dd"));
String date2 = "2015-02-02";
System.out.printf("Date %s becomes %s.\n", date2, soLastDay.lastDay(date2).toString("yyyy-MM-dd"));
}
And the test results:
Date 2015-01-27 becomes 2015-01-31.
Date 2015-02-02 becomes 2015-02-28.
If you do have Java 8, you might use code like this:
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAdjusters;
public class SoLastDayJava8 {
static DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
public LocalDate lastDay(final String yyyy_MM_dd) {
LocalDate givenDate = LocalDate.parse(yyyy_MM_dd, formatter);
return givenDate.with(TemporalAdjusters.lastDayOfMonth());
}
}
The test code changes just a bit.
public class SoLastDayJava8Test {
#Test
public void testLastDay() throws Exception {
SoLastDayJava8 soLastDay = new SoLastDayJava8();
String date1 = "2015-01-27";
System.out.printf("Date %s becomes %s.\n", date1, soLastDay.lastDay(date1));
String date2 = "2015-02-02";
System.out.printf("Date %s becomes %s.\n", date2, soLastDay.lastDay(date2));
}
}
But the results are the same.
Date 2015-01-27 becomes 2015-01-31.
Date 2015-02-02 becomes 2015-02-28.
You are messing with the TimeZones.
When you execute Date date = format.parse(stringDate); you are creating a Date object with the TimeZone of the DateFormat object. Theoretically if the TimeZone is the same for all your DateFormat and Calendar objects, you should be fine. Check if they are coherent with the getTimeZone() method.
If the TimeZone of the first DateFormat is wrong (e.g. is your TimeZone or UTC or GMT), you'll get a UTC-008 conversion in the second TimeZone (and in the Calendar) resulting in the missing day since you start from midnight.
Judging from your code is the stringDate itself that has been wrongly converted somewhere else...
I need to create a custom Date object. I get a user input in 24 hr format like hh:mm i.e. 17:49 hrs.
I want to set the hours and minutes as 17 and 49 respectively keeping other details like month , year , day as per the current time.For e.g if today is Dec 16,2014 and the time is 16:00 hrs , then i want a date object as Dec 16,2014 with time as 17:49 hrs. I know i can do this using deprecated apis , however i do not want to use them.I need the date object because i need to pass it to a java timer as java timer does not support any calendar object.
The user input comes as a string and i can parse that string using new SimpleDateFormat(HH:mm) contructor.
I tried using the Calendar.set apis but had no success.
Could some one give some direction on how to proceed.
PS. Sorry , i can't use Joda time :)
EDIT
Since getHours() and getMinutes() are deprecated and have been replaced with Calendar.HOUR_OF_DAY and Calendar.MINUTE respectively, you could use an intermediary calendar object or set the YEAR and DAY to current values.
There is a problem though, if you input next day hour like 24:01 it won't move to the next day. The previous answer, with splitting of string did the overflowing correctly.
public static void main(String[] args) throws ParseException {
final SimpleDateFormat simpleDateFormat = new SimpleDateFormat("HH:mm");
final String timeInterval = "12:01";
Date date = simpleDateFormat.parse(timeInterval);
final Calendar calendar = Calendar.getInstance(); //calendar object with current date
calendar.setTime(date); //set date with day january 1 1970, this is because you parsed only the time part, the date objects assumes you start from it's lowest value, try a System.out.println(date) before this to see.
calendar.set(Calendar.YEAR, Calendar.getInstance().get(Calendar.YEAR));
calendar.set(Calendar.DATE,Calendar.getInstance().get(Calendar.DATE));
calendar.set(Calendar.MONTH, Calendar.getInstance().get(Calendar.MONTH))
date = calendar.getTime();
System.out.println(date);
}
You can use Calendar to set the time, then extract the date with .getTime() method, which returns a java.util.Date
The idea is to split your string into two parts based on the separator :.
Then simply initialize the calendar and set the hour and minutes with those values.
public static void main(String[] args) throws ParseException {
final String userInput = "17:49";
final String[] timeParts=userInput.split(":");
Calendar cal=Calendar.getInstance(); //current moment calendar
cal.set(Calendar.HOUR_OF_DAY, Integer.parseInt(timeParts[0]));
cal.set(Calendar.MINUTE, Integer.parseInt(timeParts[1]));
cal.set(Calendar.SECOND,0); //if you don't care about seconds
final Date myDate=cal.getTime(); //assign the date object you need from calendar
//use myDate object anyway you want ...
System.out.println(myDate);
}
The following code works fine , however i don't want to use any deprecated apis.
...
...
String timeInterval = "18:01";
Date date = simpleDateFormat.parse(timeInterval);
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, date.getHours());
calendar.set(Calendar.MINUTE, date.getMinutes());
date = calendar.getTime();
System.out.println(date);
...
...
I need to process a list of Strings which may or may not be times. When I do receive a time, it will need to be converted from "HH:mm:ss" to number of milliseconds before processing:
final String unknownString = getPossibleTime();
final SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
dateFormat.setLenient(false);
try {
final Date date = dateFormat.parse(unknownString);
//date.getTime() is NOT what I want here, since date is set to Jan 1 1970
final Calendar time = GregorianCalendar.getInstance();
time.setTime(date);
final Calendar calendar = GregorianCalendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, time.get(Calendar.HOUR_OF_DAY));
calendar.set(Calendar.MINUTE, time.get(Calendar.MINUTE));
calendar.set(Calendar.SECOND, time.get(Calendar.SECOND));
final long millis = calendar.getTimeInMillis();
processString(String.valueOf(millis));
}
catch (ParseException e) {
processString(unknownString);
}
This code works, but I really dislike it. The exception handling is particularly ugly. Is there a better way to accomplish this without using a library like Joda-Time?
public static long getTimeInMilliseconds(String unknownString) throws ParseException {
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
String dateString = dateFormat.format(Calendar.getInstance().getTime());
DateFormat timeFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return timeFormat.parse(dateString + " " + unknownString).getTime();
}
Handle the ParseException outside of this method however you'd like. I.e. ("No time information provided"... or "unknown time format"... etc.)
.getTime() returns the time in milliseconds. It's part of the java.util.Date API.
Why don't you first check if the input is actually of HH:mm:ss format. You can do this by trying match input to regex [0-9]?[0-9]:[0-9]?[0-9]:[0-9]?[0-9] first and if it matches then treat it as date otherwise call processString(unknownString);
I have a string (Jan12) (generated by applying some operations on current date {20-jan-2012}) Now i want to convert back this string into Date format . Also the value should be same i.e the new Date object should have value jan12 and not (20-jan-2012) . Pls help . I have tried doing
java.sql.Date.valueOf("Jan12") [this throws IllegalArgumentException]
and also
new SimpleDateFormat("MMMyy").parse("Jan12") [By this Date gets converted to 20-jan-2012]
Output required : A Date Object having value Jan12 (12 is the year)
My Code : new java.text.SimpleDateFormat("MMMyy").format(new java.text.SimpleDateFormat("yyyy-MM-dd").parse(s)) // It is a string which gives Jan12
Now i really want to convert Mycode into a Date object
Date now = new Date();
DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
String s1 = df.format(now);
System.out.println(s1); // 2012-01-20
java.sql.Date d111=java.sql.Date.valueOf(s1);
System.out.println(d111); // 2012-01-20
DateFormat df1 = new SimpleDateFormat("MMMyy");
String s2 = df1.format(d111);
System.out.println(s2); //Jan12
Now i want s2 to be converted in Date object
#Aditya,
If you use the Str2 which gives "Jan12", there is no date part in that string and therefore if you convert it to a date object, it will get "Jan" as month, 12 as year but it cant find "day" in that String.
if you use below code
try
{
Date d2 = df1.parse(s2); //here s2 is your string which gives "JAN12"
System.out.println(d2);
}
catch(ParseException pe)
{
System.out.println("parse exception..");
}
The output to the above code will be:
Sun Jan 01 00:00:00 IST 2012
notice here that day part is reset to the first day of the month
Therefore, it is not possible to get a complete date object as your original Date, the month and year are preserved, but the day part is lost.
What do you mean "gets converted"? How your Date is displayed is a separate issue. Look into formatting a Date.
So the 12 is day, not a year - you should parse it as such. Aslo, you'll need to tell it what year this is:
System.out.println(new SimpleDateFormat("yyyyMMMdd").parse("2012" + "Jan12"));
Output
Thu Jan 12 00:00:00 EST 2012
Use the SimpleDateFormat class properly, it will do exactly what you want
String str_date="12-Jan-2012";
DateFormat formatter = new SimpleDateFormat("dd-MMM-yyyy");
Date date = (Date)formatter.parse(str_date);
Note: the formatter.parse() method throws ParseException, catch it;
If 12 is a year
Calendar calendar = Calendar.getInstance();
calendar.setTime(new SimpleDateFormat("MMMyy").parse("Jan12"));
calendar.set(Calendar.DATE, 1);
Date date = calendar.getTime(); // First Jan 2012
If 12 is a day
Calendar calendar = Calendar.getInstance();
calendar.setTime(new SimpleDateFormat("MMMdd").parse("Jan12"));
calendar.set(Calendar.YEAR, 2012);
Date date = calendar.getTime(); // 12 Jan 2012
I understand that you want to format your Date object into a String representation.
You can use SimpleDateFormat for this, analog to your second example:
Date d = new Date(112, 0, 20); //don't construct a date like this in production code, use a Calendar instance instead
String formattedDate = new SimpleDateFormat("MMMyy").format(d); // -> "Jan12"
Note that your Date object represents a specific point in time, it will always have a day and a time associated with it.
If you want to compare Dates with the resolution of a month, you have to set day and time to neutral values:
Calendar cal = Calendar.getInstance();
cal.setTime(d);
cal.set(Calendar.DAY_OF_MONTH, 1);
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);
d = cal.getTime();
Just extend Date and customize it to use your favourite parse & format methods.