Tag is not getting removed from XML even after returning null from XmlAdapter in JAXB

Question

1. I want to remove the empty tag from XML.

<Employee> <FirstName>Amit</FirstName> <LastName></LastName> </Employee>

So, in above XML lastName is coming as blank, and currently represented with Empty tags in XML. But I want the XML in below format:

<Employee> <FirstName>Amit</FirstName> </Employee>

2. So, extended the XmlAdapter like below:

   package com.jaxb.domain;
   import javax.xml.bind.annotation.adapters.XmlAdapter;
   
   import org.springframework.util.StringUtils;
   
   public class NullifyAdapter extends XmlAdapter<String, String> {
   
     @Override
     public String unmarshal(String strValue) throws Exception {
       // TODO Auto-generated method stub
       return strValue;
     }
   
     @Override
     public String marshal(String strValue) throws Exception {
       if (StringUtils.isEmpty(strValue)) {
         return null;
       }
       return strValue;
     }
   
   }
   

3. Register it a package level in the package-info.java like below:

   @XmlJavaTypeAdapters({
   @XmlJavaTypeAdapter(value=NullifyAdapter.class, type=String.class)
   })
   package com.jaxb.domain;
   
   import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
   import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapters;
   

4. After above changes the XML generated like below:

<Employee> <FirstName>Amit</FirstName> </LastName> </Employee>

5. In my jaxb binding class the field is defined as:

   @XmlElement(name = "LastName")
   protected String lastName;
   

Please suggest, how to remove lastName completely? There are lot of fields which I need to remove so want a solution on similar lines.

Answer 1

You may set the XML's LastName element definition with required=true.
This will cause the generated lastName property to be annotated with @XmlAttribute(required=true).
This way JAXB doesn't serialize the element if it's null.