JDom XML Filtering

Question

I'm trying to count how many certain elements the document has:

Iterator<?> processDescendants = doc.getDescendants(new ElementFilter("a")); 

while(processDescendants.hasNext()) {
   numPending++;
}

processDescendants = doc.getDescendants(new ElementFilter("b")); 

while(processDescendants.hasNext()) {
   numPending++;
}

There has to be an easier way... such as:

processDescendants = doc.getDescendants(new ElementFilter("a|b")); // something like Regex maybe?

Anyone can help? Thank you.

score 6 · Accepted Answer · answered Feb 07 '12 at 15:32

There are essentially two ways to do it. The easy way is to just walk the elements...

Iterator<?> processDescendants = doc.getDescendants(new ElementFilter()); 

while(processDescendants.hasNext()) {
   Element e =  processDescendants.Next();
   string currentName = e.getTagName();
   if( currentName.equals("a") || currentName.equals("b") )
   {
       numPending++;
   }
}

Or you can implement your own Filter to add the functionality

import org.jdom.filter.Filter;
import org.jdom.Element;

public class ElementRegexFilter implements Filter {

    private String regex = "";

    public ElementRegexFilter( String regex )
    {
        this.regex = regex;
    }

    public boolean matches( Object o )
    {
        if( o instanceof Element )
        {
            String ElementName = ((Element) o).getName();
            return ElementName.matches( regex );
        }
        return false;
    }

}

After getting the customized filter done. How can we use it. The matches method is automatically called ? — Hassam Abdelillah, Jan 17 '16 at 12:56

score 1 · Answer 2 · answered Feb 07 '12 at 15:20

1

I don't think there is, but you can implement your own Filter for the JDOM parser, something like MatchABElementFilter, and make the match() method return "true" for objects of type element with name "a" or "b"

answered Feb 07 '12 at 15:20

Shivan Dragon

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Nathan Hughes · Answer 3 · 2012-02-07T16:41:18.307

1

There is a declarative way to do what you want. The XPath expression for it is //a | //b.

JDOM includes a utility class for making XPath queries, you get back a list of matching nodes and can call size on the list to get your count.

edited Feb 07 '12 at 16:41

answered Feb 07 '12 at 15:50

Nathan Hughes

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JDom XML Filtering

3 Answers3