XML to Java Class

XML to Java class generation analyses an XML document and produces Java class definitions with JAXB annotations. Each XML element becomes a class with @XmlElement fields and each attribute becomes an @XmlAttribute field, ready for JAXBContext.createUnmarshaller() to unmarshal the XML.

DOM loads the entire document into a tree (good for small files, random access). SAX is event-driven and memory-efficient (good for large files, one-pass processing). StAX is a pull-based event model (more control than SAX, less memory than DOM). JAXB maps XML directly to annotated Java objects (best for schema-defined XML and most web service use cases).

Add @XmlRootElement to the class and @XmlAttribute to attribute fields. Then: JAXBContext ctx = JAXBContext.newInstance(YourClass.class); Unmarshaller u = ctx.createUnmarshaller(); YourClass obj = (YourClass) u.unmarshal(new File("data.xml")). JAXB is included in Java 8 and earlier; for Java 11+ add the jaxb-ri dependency.

The generator annotates attribute fields with @XmlAttribute and element fields with @XmlElement. In the parsed document, attributes are defined inside the opening tag (<user id="1">) while child elements are nested tags (<name>Alice</name>). The distinction matters for both reading and writing XML correctly with JAXB.

For a repeated element <item>, declare a List<Item> field annotated with @XmlElement(name = "item"). JAXB will populate the list with one object per <item> element. For @XmlElementWrapper, add a wrapper element around the list: @XmlElementWrapper(name = "items") @XmlElement(name = "item") List<Item> items.