jaxb generated class for xsd:group - xsd

Question

I have the following xsd
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
<xs:element name="root">
<xs:complexType>
<xs:sequence>
<xs:element ref="age"/>
<xs:group ref="gp.contacts"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:group name="gp.contacts">
<xs:sequence>
<xs:element ref="name" maxOccurs="unbounded"/>
<xs:element ref="phone" maxOccurs="unbounded"/>
<xs:element ref="address" maxOccurs="unbounded"/>
</xs:sequence>
</xs:group>
</xs:schema>
</xs:schema>
Then I'm using jaxb when I create xml, the output is
<root>
<age>25to35</age>
<contacts>
<name>...</name>
<name>...</name>
<name>...</name>
<phone>...</phone>
<phone>...</phone>
<phone>...</phone>
<address>..</address>
<address>..</address>
<address>..</address>
</contacts>
</root>
But I want the output to be like this
<root>
<age>25to35</age>
<contacts>
<name>...</name>
<phone>...</phone>
<address>..</address>
<name>...</name>
<phone>...</phone>
<address>..</address>
<name>...</name>
<phone>...</phone>
<address>..</address>
</contacts>
</root>
Can someone please tell me if this output can be achieved through modifying the xsd or jaxb or by any other way.

Answer 1

If you want to allow unbounded sequences, each containing one (name, phone, address), in that order, you need to remove it from the containing elements (which will now allow and require only one of each, which is the default):
<xs:group name="gp.contacts">
<xs:sequence>
<xs:element name="name"/>
<xs:element name="phone"/>
<xs:element name="address"/>
</xs:sequence>
</xs:group>
Then you need to declare that the sequence is unbounded. Since you declared a group, you do that when you reference it:
<xs:element name="root">
<xs:complexType>
<xs:sequence>
<xs:element ref="age"/>
<xs:group ref="gp.contacts" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
This might not solve your problem yet. You said that JAXB was generating the XML you included in your question with the <contacts> element. Your schema does not validate that. I assume you are wrapping that in JAXB (you didn't show your code), but if you can edit the schema it's better to do so since your XML will validate against it). The schema as is actually validates this:
<root>
<age>25to35</age>
<name>...</name>
<name>...</name>
...
<address>..</address> ...
<phone>...</phone>
...
</root>
With the modifications, now it validates this:
<root>
<age>25to35</age>
<name>...</name>
<phone>...</phone>
<address>..</address>
<name>...</name>
<phone>...</phone>
<address>..</address>
<name>...</name>
<phone>...</phone>
<address>..</address>
...
</root>
For it to validate the XML you want it to generate, with the <name>, <phone> and <address> sequences nested in <contacts>, you need to add a declaration for the <contacts> element in XML Schema, and reference the group from inside it:
<xs:element name="root">
<xs:complexType>
<xs:sequence maxOccurs="unbounded">
<xs:element name="age" type="xs:string"/>
<xs:element name="contacts">
<xs:complexType>
<xs:group ref="gp.contacts" maxOccurs="unbounded"/>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
Your schema also has doubled <schema> root elements (I assumed that was a cut-and-paste typo.)
If you fix these problems, you can use the schema to generate classes for JAXB that will create XML the instances you want.