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jaxbxsddefault-value
A7iz
A7iz

Reputation: 125

JAXB objects initialized with default values

There is little problem with JAXB.

Given:

Required

Get java object (root element) which fully represent xml and every member initialized by default values.

when I try to marshall xml without explicitly setting values, default values doesn't make sence... is there any way to marshall xml populated with default values without customization of generated classes?

example of .xsd:

<xs:element name="document">
    <xs:complexType>
        <xs:sequence>
            <xs:element ref="d_int"/>
            <xs:element ref="d_double"/>
            <xs:element ref="d_string"/>
        </xs:sequence>
    </xs:complexType>
</xs:element>

<xs:element name="d_int" type="xs:int" default="-1"/>
<xs:element name="d_double" type="xs:double" default="-1.0"/>
<xs:element name="d_string" type="xs:string" default="false"/>

and java class:

public class Document {
    @XmlElement(name = "d_int", defaultValue = "-1")
    protected int dInt;
    @XmlElement(name = "d_double", defaultValue = "-1.0")
    protected double dDouble;
    @XmlElement(name = "d_string", required = true, defaultValue = "Default")
    protected String dString;
...
}

Upvotes: 11

Views: 28031

Answers (2)

Stefan Bormann
Stefan Bormann

Reputation: 693

For an initialization of the class members from XSD supplied defaults, you can use the default-value-plugin of XJC.

See the website of the plugin.

Note that the ant task definition as explained in that documentation did not work for me. As explained here, the class paths for XJC and the plugin have to be separated. Specifying the path to the plugin when calling it works for me:

<xjc schema="some.xsd" >
    <arg value="-Xdefault-value"/>
    <classpath>
        <pathelement location="lib/xjc-plugins/jaxb2-default-value-1.1.jar"/>
    </classpath>
</xjc>

Upvotes: 1

Ilya
Ilya

Reputation: 29693

default value that is in annotations works only after unmarshalling.
unmarshal this 

<document>
   <d_int/>
   <d_double/>
   <d_string/>
</document>

and you will get object with default values (-1, -1.0, "Default")

If you want set default values to marshalling, you should do this 

public class Document {
    @XmlElement(name = "d_int", defaultValue = "-1")
    protected int dInt = 100;
    @XmlElement(name = "d_double", defaultValue = "-1.0")
    protected double dDouble = -100;
    @XmlElement(name = "d_string", required = true, defaultValue = "Default")
    protected String dString = "def";
...
}

jaxb generate default values only for unmarshalling

Upvotes: 22

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