Скачать или смотреть Resolving the ZonedDateTime Unmarshalling Error in Java XML Processing

Learn to fix the `NoSuchMethodException` while unmarshalling `ZonedDateTime` using an `XmlAdapter` in Java. This guide provides practical solutions and examples.
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Understanding and Resolving the ZonedDateTime Unmarshalling Error in Java

When working with XML processing in Java, you might encounter issues while trying to unmarshal a ZonedDateTime. A common scenario involves an error like java.lang.NoSuchMethodException: java.time.ZonedDateTime.<init>(). The problem typically arises when incorrect parsing methods or formats are used. This guide explores this issue and provides a practical solution to effectively handle ZonedDateTime unmarshalling in Java.

The Problem: Unmarshalling Error

In many cases, developers need to convert XML strings representing date and time into appropriate Java objects like ZonedDateTime. Let's say the XML contains a date string formatted like this: "2019-04-01T10:00:00.000-0500". You may attempt to use an XmlAdapter to handle the conversion, but this might trigger an error if the string isn’t parsed correctly.

Here's a sample code segment that demonstrates the error:

[[See Video to Reveal this Text or Code Snippet]]

While using the above code, the exception appears due to the usage of LocalDateTime, which does not carry time zone information. Consequently, upon unmarshalling, the error seems to indicate that the ZonedDateTime instance cannot be instantiated.

The Solution: Proper Parsing of ZonedDateTime

To resolve the issue, you need to directly parse the input string into ZonedDateTime instead of first converting it into LocalDateTime. This can be achieved using ZonedDateTime.parse together with a properly defined DateTimeFormatter. Here's how to implement that:

Revised Code Example

Here’s how you can adjust the adapter to parse strings with timezone directly to ZonedDateTime:

[[See Video to Reveal this Text or Code Snippet]]

Key Points to Consider

Use ZonedDateTime.parse(): This is essential because it directly converts the string to a ZonedDateTime object with the correct timezone information, preventing constructors from being uncalled.

DateTimeFormatter: Always ensure that the formatter matches the input string format exactly, including the timezone representation.

Annotations (@ XmlJavaTypeAdapters): If you're mapping this in a Java class, you can annotate your field with @ XmlJavaTypeAdapters to let JAXB know how to handle the ZonedDateTime during marshalling and unmarshalling.

Conclusion

Dealing with dates and times in Java, particularly with XML, can be tricky. The NoSuchMethodException while unmarshalling ZonedDateTime usually points to parsing issues. By directly using ZonedDateTime.parse() instead of LocalDateTime, you can correctly convert your XML date strings into Java objects. Implementing the above solution will help you effectively handle unmarshalling errors related to ZonedDateTime in Java.

Stay tuned for more insightful posts on Java programming and XML processing!