java - How to unmarshall XML to this class? -

i unmarshall xml using jaxb unmarshaller object of type.

public class pair<t1,t2> implements serializable {     private t1 first;      private t2 second;      public pair(t1 first, t2 second) {         this.first = first;         this.second = second;     }      public t1 getfirst() {         return first;     }      public void setfirst(t1 first) {         this.first = first;     }      public t2 getsecond() {         return second;     }      public void setsecond(t2 second) {         this.second = second;     } }   public class trippair<t1,t2> extends pair<t1,t2> {      public trippair(t1 first, t2 second) {         super(first, second);     } }  public class fare extends pricing implements comparable<fare> {      private list<trippair<integer,integer>> trips = new linkedlist<>(); } 

xml file

<faregroups>     <trips>         <second>37</second>         <first>0</first>     </trips> </faregroups> 

xml file have other data , unmarshalled, unfortunately data elements first , second not unmarshalled. tried add @xmlelement annotations on these fields pair class, without sucesss.

using xmladapter

public class pairadapter extends xmladapter<string, integer> {      public string marshal(integer val) throws exception {         return val.tostring();     }      public integer unmarshal(string val) throws exception {         return integer.valueof(val);     } }  public class pair<t1,t2> implements serializable {     @xmljavatypeadapter(pairadapter.class)     private t1 first;      @xmljavatypeadapter(pairadapter.class)     private t2 second; } 

you need add zero-arg constructor, or create xmladapter pair class unmarshal correctly (see: http://blog.bdoughan.com/2010/12/jaxb-and-immutable-objects.html).

update

i'm using jaxb marshaller , when made debugging of non-marshalled element, has wrong type. elementnsimpl instead of integer.

as far jaxb concerned first , second treated type object, since derives metadata @ class level pair instenad of type level pair<integer, integer>. because of xml need qualify xml elements necessary type information. done using xsi:type attribute.

public class pair<t1,t2> implements serializable {     private t1 first;      private t2 second; 

try populating object model data want , marshalling , see xml should unmarshal operation.