Conversion of DateTime in java

Question

One of the fields of my json is a String which contains time in the following format: 2017-04-04T20:22:33 or even 2017-04-07T12:21:10.0355277+00:00. My task is to convert it to a more simple representation like this: "Apr-4 20:22". I was thinking about about creating a SimpleDateFormat, however it doesn't seem to work with such DateTime format.

Is there any effective way to handle this task?

SimpleDateFormat will work, if you find the problem with it, can you post what have u done? — nafas, Apr 07 '17 at 12:27
The thing is, SimpleDateFormat needs a String-pattern as one of its parameters. Ok, I pass it a "MMM d H:mm" value to match the result I need. However when I use the "format" method later, it needs me to pass a date into it, but I don't have any clues on how to get the date from the Strings I've described. — SpKiwi, Apr 07 '17 at 12:30
http://stackoverflow.com/questions/2375222/java-simpledateformat-for-time-zone-with-a-colon-separator where are all possible formats you want — Yu Jiaao, Apr 07 '17 at 12:31
You have to use `parse` to convert a `String` into a `Date`, not `format` method. Please, have a look to https://docs.oracle.com/javase/8/docs/api/java/text/DateFormat.html#parse-java.lang.String-. Consider to switch to Java 8 Date-Time framework is possible. — riccardo.cardin, Apr 07 '17 at 12:37
Tip: Search Stack Overflow for ISO 8601, OffsetDateTime, ZoneOffset, and DateTimeFormatter. Your Question and these Answers are using troublesome old date-time classes now supplanted by the java.time classes. `OffsetDateTime.parse( "2017-04-07T12:21:10.0355277+00:00" )` — Basil Bourque, Apr 07 '17 at 17:32

dev8080 · Answer 1 · 2017-04-07T12:52:14.767

3

I think you're confused between parse and format:

public String convert(String inputStr, String inputFormat, String outputFormat){

    Date date = new SimpleDateFormat(inputFormat).parse( inputStr );
    String outputStr = new SimpleDateFormat(outputFormat).format( date );

    return outputStr;
}

Use it like this:

convert("2017-04-04T20:22:33", "yyyy-MM-dd'T'HH:mm:ss", "d-MMM HH:mm");

Since you don't need the extraneous portions of the String you can remove it entirely before passing to the above method.

edited Apr 07 '17 at 12:52

answered Apr 07 '17 at 12:40

dev8080

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T should be in quotes like 'T' in format – Ravi Theja Apr 07 '17 at 12:49
@RaviTeja yes, that's right. – dev8080 Apr 07 '17 at 12:52

score 2 · Accepted Answer · answered Apr 07 '17 at 12:47

2

Try this

 String date="2017-04-04T20:22:33";
 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
 SimpleDateFormat sdf1 = new SimpleDateFormat("MMM-dd HH:mm");
 try{
    Date parseDate = sdf.parse(date);
    String output = sdf1.format(parseDate);
 }catch(Exception e) {

 }

answered Apr 07 '17 at 12:47

Ravi Theja

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FYI: The troublesome old date-time classes such as `Date` and `Calendar` are now legacy, supplanted by the java.time classes. – Basil Bourque Apr 07 '17 at 17:24

score 0 · Answer 3 · answered Apr 07 '17 at 12:32

0

You can use DateUtils

Date truncatedDate = DateUtils.truncate(new Date(), Calendar.DATE);

or you can try localDateTime

LocalDateTime.now().truncatedTo(ChronoUnit.MINUTES)

answered Apr 07 '17 at 12:32

neverwinter

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score 0 · Answer 4 · answered Apr 07 '17 at 12:39

I sometimes use a pattern:

private static final Pattern XSD_DATETIME_PATTERN = Pattern.compile(
        "([+-]?[0-9]{4})-(1[0-2]|0[1-9])-([0-9]{2})"
        + "[Tt]([0-9]{2}):([0-9]{2}):([0-9]{2})(?:[.]([0-9]+))?"
        + "(?:([Zz])|([+-][0-9]{2}:[0-9]{2}))?");


public static Date parseXsdDateTime(String s) {
    Matcher matcher = XSD_DATETIME_PATTERN.matcher(s);
    if (!matcher.matches()) {
        throw new IllegalArgumentException(
                "Unparseable date: \"" + s + "\"");
    }
    // Determine timezone
    TimeZone tz;
    if (matcher.group(8) != null) {
        tz = TimeZone.getTimeZone("GMT");
    } else if (matcher.group(9) != null) {
        tz = TimeZone.getTimeZone("GMT" + matcher.group(9));
    } else {
        tz = TimeZone.getDefault();
    }
    Calendar cal = Calendar.getInstance(tz);
    cal.set(Calendar.YEAR, Integer.parseInt(matcher.group(1)));
    cal.set(Calendar.MONTH, Integer.parseInt(matcher.group(2))-1);
    cal.set(Calendar.DAY_OF_MONTH, Integer.parseInt(matcher.group(3)));
    cal.set(Calendar.HOUR_OF_DAY, Integer.parseInt(matcher.group(4)));
    cal.set(Calendar.MINUTE, Integer.parseInt(matcher.group(5)));
    cal.set(Calendar.SECOND, Integer.parseInt(matcher.group(6)));
    String millis = matcher.group(7);
    if (millis == null) {
        cal.set(Calendar.MILLISECOND, 0);
    } else {
        if (millis.length() > 3) {
            millis = millis.substring(0, 3);
        } else {
            while (millis.length() < 3) {
                millis += "0";
            }
        }
        cal.set(Calendar.MILLISECOND, Integer.parseInt(millis));
    }
    return cal.getTime();
}

Why the hell has he to use such complex code. Using `DateFormat` he has got all the methods needed. — riccardo.cardin, Apr 07 '17 at 12:40
`SimpleDateFormat` was already present in Java 6 https://docs.oracle.com/javase/6/docs/api/java/text/DateFormat.html#parse-java.lang.String- — riccardo.cardin, Apr 07 '17 at 12:49
@riccardo.cardin not the X field: https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html — Maurice Perry, Apr 07 '17 at 12:52
Mmmm...subtle. You're right. If so, you should specify it in you answer :) Cheers — riccardo.cardin, Apr 07 '17 at 12:54

Conversion of DateTime in java

4 Answers4