[SOLVED] Sorting an XML in Java

Sorting an XML in Java

I have an XML similar to below, which needs to be sorted using the date field.

<root> 
    <Node1>
        <date></date> 
    </Node1> 
    <Node1> 
        <date></date> 
    </Node1> 
    <Node1> 
        <date></date> 
    </Node1> 
    <Node1> 
        <date></date> 
    </Node1> 
    <Node2> 
        <date></date> 
    </Node2> 
    <Node2> 
        <date></date> 
    </Node2> 
    <Node2> 
        <date></date> 
    </Node2> 
    <Node2> 
        <date></date> 
    </Node2> 
</root>

I would like to sort the XML based on the date(say ascending order), irrespective of whether the date is under Node1 or Node2. Actually, in Java code I have two separate lists, one with Node1 objects and other with Node2 objects. I can sort the list in any order separately inside java. But I need to have the dates sorted irrespective of the nodes it is appearing on the XML. What is the best approach to sort this way in Java?

Actually I am using Castor for marshaling the java objects to XML. If you know this can be done with Castor, that will be great!

Solution

I'd use XSLT, it has probs with sorting dates that you'll need to work round, simplest way if you can control it is to have sortable date format like yyyymmdd

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

  <xsl:template match="root">
    <xsl:copy>
        <xsl:apply-templates>
           <xsl:sort data-type="number" select="date"/>
        </xsl:apply-templates>
    </xsl:copy>
  </xsl:template>

  <xsl:template match="*">
      <xsl:copy>
          <xsl:apply-templates/>
      </xsl:copy>
  </xsl:template>

</xsl:stylesheet>