How to convert string to LocalDateTime,how to solve string format "yyyymmddhhMMss" to LocalDateTime

Question

How to convert string to LocalDateTime,how to solve string format "yyyymmddhhMMss" to LocalDateTime

String dateTime = "20221120000000";

LocalDateTime localDateTime = LocalDateTime.parse(dateTime);

Exception in thread "main" java.time.format.DateTimeParseException: Text '20221120000000' could not be parsed at index 0
    at java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:1948)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1850)
    at java.time.LocalDateTime.parse(LocalDateTime.java:492)
    at java.time.LocalDateTime.parse(LocalDateTime.java:477)
    at com.company.Main.main(Main.java:21)

Answer 1

This should do it:

String dateTimeString = "20221120000000";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
LocalDateTime dateTime = LocalDateTime.parse(dateTimeString, formatter);

If you dont want to use the DateTimeFormatter, your String needs to be in ISO format

Edit: it isn’t in the question, but you said elsewhere:

I want it to convert to this format("yyyy-MM-dd HH:mm:ss") …

A LocalDateTime cannot have a format (its toString method invariably produces an ISO 8601 format). So to obtain a specific format you need to convert to a String again:

DateTimeFormatter wantedFormatFormatter
        = DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss");
String formattedDateTime = dateTime.format(wantedFormatFormatter);
System.out.println(formattedDateTime);

This outputs:

2022-11-20 00:00:00

(I hope you didn’t expect a LocalDateTime with the format you mentioned. In case you did see this question: Can’t rid of 'T' in LocalDateTime.)