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Learn how to fix the `UnrecognizedPropertyException` error while converting XML to Java POJO using Jackson's XmlMapper. This guide walks you through the necessary annotations to extract data properly.
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How to Resolve UnrecognizedPropertyException When Converting XML to Java POJO

When working with Java and XML, one common issue you might encounter is the UnrecognizedPropertyException error, particularly when using the Jackson library to convert XML into Java Plain Old Java Objects (POJOs). This error typically indicates that your Java class structure does not align properly with the XML input.

In this guide, we’ll explore a specific example of this problem and how to resolve it effectively, ensuring you can extract all necessary elements from your XML.

The Problem

Imagine you have the following XML structure:

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

You intend to convert this XML into a Java POJO and have created the corresponding classes. However, when you try to deserialize the XML, you encounter the following exception:

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

The error essentially tells you that Jackson cannot recognize a field in your Msg class.

Understanding the Root Cause

The root cause of this exception lies in the way Jackson interprets XML attributes and values. Jackson expects specific annotations on the fields of your Java classes to correctly interpret the XML structure. Without these annotations, Jackson cannot distinguish between XML attributes and text values.

The Solution

To solve the issue, you need to specify how Jackson should handle the fields in the Msg class. You can achieve this by using the following annotations:

@ JacksonXmlText - This annotation is used for fields that represent text content in the XML element.

@ JacksonXmlProperty(isAttribute = true) – This indicates that a field represents an XML attribute rather than an element value.

Implementation Steps

Here’s how you can modify your Msg class:

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

Complete Java POJO Class

Ensure that your complete POJO structure includes the MyPojo and Messages classes, structured as follows:

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

Running the Code

After applying these changes, run your main method again. The conversion from XML to Java POJO should now work without exceptions, successfully extracting:

Preview: 0

Type: TEST

Message: Why this is failing

Conclusion

In summary, the UnrecognizedPropertyException error when converting XML to Java POJO can be easily fixed by correctly annotating your Java classes. By using the annotations @ JacksonXmlText for text values and @ JacksonXmlProperty(isAttribute = true) for XML attributes, you can ensure that Jackson processes your XML data as intended.

With these changes in place, you'll be able to avoid serialization issues and successfully extract all necessary data from your XML input. Feel free to implement these changes in your code and enjoy a smoother XML-to-Java conversion process!