6.2.7.2 The Annotation `XmlList`

The attribute XmlList instructs JAXB that a list value is to be represented as a blank separated list of values of some simple type rather than a list of individual child elements. The annotated class Sentence

@XmlType
class Sentence {
  @XmlElement
  List<String> word;
}

produces XML such as

<sentence>
  <word>This</word>
  <word>is</word>
  <word>verbose</word>
</sentence>

In contrast, the addition of XmlList

@XmlType
class Sentence {
  @XmlElement
  @XmlList
  List<String> word;
}

results in

<sentence>
  <word>This is terse</word>
</sentence>

Needless to say, using the XML representation of lists for strings is risky unless you can be sure that no string value contains a blank.

Also, remember the restriction for XML Schema's xsd:list, which is only valid for types that are simple according to XML Schema rules. An class such as Paragraph

@XmlType
class Paragraph {
  @XmlElement
  @XmlList      // Not valid - Sentence isn't a simple type.
  List<Sentence> word;
}

is bound to fail as soon as JAXB inspects the annotations. (The Java compiler has no way of knowing that something is amiss here.)

table of contents

6.2.7.2 The Annotation XmlList

6.2.7.2 The Annotation `XmlList`