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String to Date Conversion mm/dd/yy to YYYY-MM-DD in java [duplicate]

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Java Date Error
(8 answers)
Closed 4 years ago.
I want to convert String values in the format of mm/dd/yy to YYYY-MM-DD Date. how to do this conversion?
The input parameter is: 03/01/18
Code to convert String to Date is given below
public static Date stringToDateLinen(String dateVlaue) {
Date date = null;
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
try {
date = formatter.parse(dateVlaue);
} catch (ParseException e) {
e.printStackTrace();
}
return date;
}
When tried to convert using this method it shows the following error
java.text.ParseException: Unparseable date: "03/01/18"

As you say the input is in a different format, first convert the String to a valid Date object. Once you have the Date object you can format it into different types , as you want, check.
To Convert as Date,
SimpleDateFormat formatter = new SimpleDateFormat("MM/dd/yy");
date = formatter.parse(dateVlaue);
To Print it out in the other format,
SimpleDateFormat formatter1 = new SimpleDateFormat("yyyy-MM-dd");
dateString = formatter1.format(date)

You are writing it the wrong way. In fact, for the date you want to convert, you need to write
SimpleDateFormat formatter = new SimpleDateFormat("MM/dd/yy");

The format you are passing to SimpleDateFormat is ("yyyy-MM-dd") which expects date to be in form 2013-03-01 and hence the error.
You need to supply the correct format that you are passing your input as something like below
public static Date stringToDateLinen(String dateVlaue) {
Date date = null;
SimpleDateFormat formatter = new SimpleDateFormat("dd/MM/yy");
try {
date = formatter.parse(dateVlaue);
} catch (ParseException e) {
e.printStackTrace();
}
return date;
}

The solution for the above problem
Convert the String date value in the Format of "dd/mm/yy" to Date.
By using the converted Date can able to frame the required date format.
The method has given below
public static String stringToDateLinen(String dateVlaue) {
Date date = null;
SimpleDateFormat formatter = new SimpleDateFormat("dd/mm/yy");
String dateString = null;
try {
// convert to Date Format From "dd/mm/yy" to Date
date = formatter.parse(dateVlaue);
// from the Converted date to the required format eg : "yyyy-MM-dd"
SimpleDateFormat formatter1 = new SimpleDateFormat("yyyy-MM-dd");
dateString = formatter1.format(date);
} catch (ParseException e) {
e.printStackTrace();
}
return dateString;
}

EDIT: Your question said “String values in the format of mm/dd/yy”, but I understand from your comments that you meant “my input format is dd/mm/yy as string”, so I have changed the format pattern string in the below code accordingly. Otherwise the code is the same in both cases.
public static Optional<LocalDate> stringToDateLinen(String dateValue) {
DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("dd/MM/yy");
try {
return Optional.of(LocalDate.parse(dateValue, dateFormatter));
} catch (DateTimeParseException dtpe) {
return Optional.empty();
}
}
Try it:
stringToDateLinen("03/01/18")
.ifPresentOrElse(System.out::println,
() -> System.out.println("Could not parse"));
Output:
2018-01-03
I recommend you stay away from SimpleDateFormat. It is long outdated and notoriously troublesome too. And Date is just as outdated. Instead use LocalDate and DateTimeFormatter from java.time, the modern Java date and time API. It is so much nicer to work with. A LocalDate is a date without time of day, so this suites your requirements much more nicely than a Date, which despite its name is a point in time. LocalDate.toString() produces exactly the format you said you desired (though the LocalDate doesn’t have a format in it).
My method interprets your 2-digit year as 2000-based, that is, from 2000 through 2099. Please think twice before deciding that this is what you want.
What would you want to happen if the string cannot be parsed into a valid date? I’m afraid that returning null is a NullPointerException waiting to happen and a subsequent debugging session to track down the root cause. You may consider letting the DateTimeParseException be thrown out of your method (just declare that in Javadoc) so the root cause is in the stack trace. Or even throw an AssertionError if the situation is not supposed to happen. In my code I am returning an Optional, which clearly signals to the caller that there may not be a result, which (I hope) prevents any NullPointerException. In the code calling the method I am using the ifPresentOrElse method introduced in Java 9. If not using Java 9 yet, use ifPresent and/or read more about using Optional elsewhere.
What went wrong in your code?
The other answers are correct: Your format pattern string used for parsing needs to match the input (not your output). The ParseException was thrown because the format pattern contained hyphens and the input slashes. It was good that you got the exception because another problem is that the order of year, month and day doesn’t match, neither does the number of digits in the year.
Link
Oracle tutorial: Date Time explaining how to use java.time.

Need to Get the current DateTime in the Talend Studio?

I am working the Talend studio tool for data migration. Now I want to set the Current DateTime in the Date field.
I get the DateTime from this code TalendDate.getDate("yyyy-MM-dd HH:mm:ss") but it returns String type data. But I need Date type to insert.Is there any String to date (Sample insert is like this:1999-12-13 16:14:48) conversion is in the Talend Studio.

You can use routine function TalendDate.parseDate to convert a String to a Date.
TalendDate.parseDate("yyyy-MM-dd HH:mm:ss", yourStringData);
If you want the current datetime:
TalendDate.parseDate("yyyy-MM-dd HH:mm:ss", TalendDate.getDate("yyyy-MM-dd HH:mm:ss"));
But this makes no sense. Parsedate function is prepared to receive a string and convert it to a Date object. Date objects have it's own format, so you don't have to care how is stored, you need to change the Date format in the moment you show it, but not when you store it:
// this will produce a correct Date Object to store in your Date field
Date currentDate = TalendDate.getCurrentDate();
When you need to show/print it use SimpleDateFormat for example if you want to show 2015-07-05 16:00:00 you must do like this:
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss);
System.out.println("My date formatted is: " + sdf.format(currentDate ));

its very simple with the use of DateFormat in java
public static void convert(String inputDate) throws ParseException {
DateFormat format = new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss");
Date d = format.parse(inputDate); // example 1999-12-13 16:14:48
System.out.println(d);
}

How to converted timestamp string to a date in java

I have a string "1427241600000" and I want it converted to "yyyy-MM-dd" format.
I have tried, but I am not able to parse it, please review the below code
try {
String str = "1427241600000";
SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd");
Date date =sf.parse(str);
System.out.println(date);
} catch (ParseException e) {
e.printStackTrace();
}
I would like to know where I went wrong.

You should try it the other way around. First get the Date out of the milliTime and then format it.
String str = "1427241600000";
SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd");
Date date = new Date(Long.parseLong(str));
System.out.println(sf.format(date));

the conversion is highly dependent on what format the timestamp is in. But i assume the whole thing should actually be a long and is simply the systemtime from when the timestamp was created. So this should work:
String str = ...;
Date date = new Date(Long.parseLong(str));

Use Date date =new Date(Long.parseLong(str)); to convert your String to Date object.
if you are using SimpleDateFormat() the format specified as a parameter to this function should match the format of the date in the String (str in your case). In your case yyyy-MM-dd does not match the format of the time stamp (1427241600000).

You can do it like this:
use a SimpleDateFormat with an appropriate format string (be careful to use the correct format letters, uppercase and lowercase have different meanings!).
DateFormat format = new SimpleDateFormat("MMddyyHHmmss");
Date date = format.parse("022310141505");

Converting timestamp from parse.com in java

I'm getting my object's createdAt timestamp back from parse.com as 2014-08-01T01:17:56.751Z. I have a class that converts it to relative time.
public static String timeAgo(String time){
PrettyTime mPtime = new PrettyTime();
long timeAgo = timeStringtoMilis(time);
return mPtime.format( new Date( timeAgo ) );
}
public static long timeStringtoMilis(String time) {
long milis = 0;
try {
SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = sd.parse(time);
milis = date.getTime();
} catch (Exception e) {
e.printStackTrace();
}
return milis;
}
The problem is that this parses the date wrongly. Right now the result says 4 decades ago and this very wrong. What I'm I doing wrong?

Your current date format "yyyy-MM-dd HH:mm:ss" does not work for the given example 2014-08-01T01:17:56.751Z. The format is missing the characters T and Z and the milliseconds.
Change it to:
new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
to fix it.
Also check the examples in the JavaDoc of SimpleDateFormat, because it also shows the correct date format for your example: http://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html.

Expanding #Tom's answer:
The problem
When hardcoding 'Z', you assume that all dates were saved as UTC - which doesn't necessarily have to be the case.
The problem is that SimpleDateFormat does not recognize the literal 'Z'as an alias for UTC's '-0000' offset (For whatever reason, since it claims to be ISO-8601 compliant).
So you can't do
new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
since this wrongly assumes all dates will always be written as in UTC, but you can't do
new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ");
either, since this would not be able to parse the date when the literal 'Z' occurs.
Solution 1: Use javax.xml.bind.DatatypeConverter
This datatype converter actually is ISO8601 compliant and can be used as easy as
import javax.xml.bind.DatatypeConverter;
public Long isoToMillis(String dateString){
Calendar calendar = DatatypeConverter.parseDateTime(dateString);
return calendar.getTime().getTime();
}
If you use JAXB anyway, that would be the way to go.
Solution 2: Use conditional formats
final static String ZULUFORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";
final static String OFFSETFORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSSZ";
/* This is a utility method, so you want the calling method
* to be informed that something is wrong with the input format
*/
public static Long isoToMillis(String dateString) throws ParseException{
/* It is the default, so we should use it by default */
String formatString = ZULUFORMAT;
if(! dateString.endsWith("Z") ) {
formatString = OFFSETFORMAT;
}
SimpleDateFormat sd = new SimpleDateFormat(formatString);
return sd.parse(dateString).getTime();
}
If you don't already use JAXB, you might want to put this method into a utility class.

Date conversion in Java

How can I take a string in a format such as: 2008-06-02 00:00:00.0 and convert it to: 02-Jun-2008?
Can I somehow take the original string, convert it to a Date object, then use a formatter to get the final output (rather than parsing the string myself)? Thanks!

You can use SimpleDateFormat to convert between a String and a Date object and vice versa based on a pattern. Click the API link, you'll see patterns being explained in detail. A 4-digit year can be represented with yyyy, a 3-character month abbreviation can be represented with MMM and so on.
First you need to parse the String of the first format into a Date object:
SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
Date date = sdf1.parse(inputString);
Then you need to format the Date into a String of the second format:
SimpleDateFormat sdf2 = new SimpleDateFormat("dd-MMM-yyyy", Locale.ENGLISH);
String outputString = sdf2.format(date);
Note that you need to take the Locale into account as well to get the month to be printed in English, else it will use the platform's default locale to translate the month.

Use 2 instances of SimpleDateFormat class. One for converting your input string to date and second to convert date back to string but in another format.
Here is an example of using SimpleDateFormat.

DateFormat startFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.S");
DateFormat endFormat = new SimpleDateFormat("dd-MM-yyyy");
String outputString = null;
try {
Date date = startFormat.parse(inputString);
outputString = endFormat.format(date);
} catch(ParseException pe) {
throw new IllegalArgumentException(inputString + " is not properly formated.", pe);
}

You can definitely use SimpleDateFormat class like others have recommended.
Another suggestion if it applies in your case. If you are getting this data from a sql query you can also use to_char() method to format it in the query itself. For example: to_char(column_name,'DD-MON-YYYY')