How to convert XML file having "ref ids" and "ids" in java

I have a sample xml like below.I have a requirement were I need to cross reference various xml attributes. I have identified the below format, but not sure how to interpret this in java.

How do i interpret this xml in java. For example, how do I retireve details of a teacher with teacher id="T72100";

<schedule term="Fall" year="98" xmlns:data="x-schema:idSchema.xml"
                                xmlns:ref="x-schema:refSchema.xml">
  <classes>
    <data:class id="ENGL6004">
      <title>From Here to Eternity: Studies in the Futureenter code here
        and other Temporal Genres</title>
      <ref:teacherRef ref="T31330"/>
      <students>
        <ref:student ref="S50245"/>
        <ref:student ref="S87901"/>
        <ref:student ref="S19272"/>
        <ref:student ref="S48984"/>
      </students>
    </data:class>
    <data:class id="HIST6010">
      <title>The You Decade: A History of Finger Pointing
        in Post-War America</title>
      <ref:teacher ref="T72100"/>
      <students>
        <ref:student ref="S60912"/>
        <ref:student ref="S87901"/>
        <ref:student ref="S84281"/>
        <ref:student ref="S44098"/>
      </students>
    </data:class>
    <data:class id="ENGL6020">
      <title>Reading between the Lines: The Literature
        of Waiting</title>
      <ref:teacher ref="T31330"/>
      <students>
        <ref:student ref="S84281"/>
        <ref:student ref="S19272"/>
        <ref:student ref="S48984"/>
        <ref:student ref="S44098"/>
      </students>
    </data:class>
  </classes>
  <teachers>
    <data:teacher id="T31330">
      <name>Margaret Doornan</name>
      <position>Associate Professor</position>
      <classes>
        <ref:class ref="ENGL6004"/>
        <ref:class ref="ENGL6020"/>
      </classes>
    </data:teacher>
    <data:teacher id="T72100">
      <name>Hal Canter</name>
      <position>Instructor</position>
      <classes>
        <ref:class ref="HIST6010"/>
      </classes>
    </data:teacher>
  </teachers>
  <students>
    <data:student id="S44098">
      <name>Kelly Griftman</name>
      <year>Senior</year>
      <status>full-time</status>
      <classes>
        <ref:class ref="HIST6010"/>
        <ref:class ref="ENGL6020"/>
      </classes>
    </data:student>
    <data:student id="S48984">
      <name>Norbert James</name>
      <year>Senior</year>
      <status>full-time</status>
      <classes>
        <ref:class ref="ENGL6004"/>
        <ref:class ref="ENGL6020"/>
      </classes>
    </data:student>
    </students>
</schedule>