Question

Need help selecting distinct names when parsing an XML document using Java

Asked by: fsyed

Dear fellow developers:

I am parsing an XML document that contains many names, using the SAX method, and then printing them out to the console.  The names I am selecting are found within the <narrator> element within the XML document.  As I parse the XML document, when I find the <narrator> element, I create a narrator object, set the name attribute for that object, and then add it to an ArrayList.  Once I finished adding objects to the ArrayList, I print out the contents.

Because many of the names repeat within the XML document, I am trying to figure out a way to select ONLY the distinct names from the XML document, and then add it to the ArrayList so that my output contains ONLY unique names.  This would be similar to using the SQL query, SELECT DISTINCT NAME FROM TABLE....

Can anyone show me how to do this?  I have attached my Java code below.

Thanks in advance to all who reply.

package example;
 
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
 
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
 
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
 
 
import org.xml.sax.helpers.DefaultHandler;
 
public class SAXParserExample extends DefaultHandler {
 
	List myEmpls;
	
	private String tempVal;
	
	//to maintain context
	private Narrator tempEmp;
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
 
		SAXParserExample spe = new SAXParserExample();
		spe.runExample();
 
	}
	
	public SAXParserExample(){
		myEmpls = new ArrayList();
	}
	
	public void runExample() {
		parseDocument();
		printData();
	}
	
	private void parseDocument() {
		
		//get a factory
		SAXParserFactory spf = SAXParserFactory.newInstance();
		try {
		
			//get a new instance of parser
			SAXParser sp = spf.newSAXParser();
			
			//parse the file and also register this class for call backs
			sp.parse("SahihAlBukharicomplete5new.xml", this);
			
		}catch(SAXException se) {
			se.printStackTrace();
		}catch(ParserConfigurationException pce) {
			pce.printStackTrace();
		}catch (IOException ie) {
			ie.printStackTrace();
		}
	}
 
	/**
	 * Iterate through the list and print
	 * the contents
	 */
	private void printData(){
		
		System.out.println("No of Narrators '" + myEmpls.size() + "'.");
		
		Iterator it = myEmpls.iterator();
		while(it.hasNext()) {
			System.out.println(it.next().toString());
		}
	}
	
 
	//Event Handlers
	public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
		//reset
		tempVal = "";
		if(qName.equalsIgnoreCase("narrator")) {
			//create a new instance of employee
			tempEmp = new Narrator();
			
		}
	}
	
 
	public void characters(char[] ch, int start, int length) throws SAXException {
		tempVal = new String(ch,start,length);
	}
	
	public void endElement(String uri, String localName, String qName) throws SAXException {
 
		if(qName.equalsIgnoreCase("narrator")) {
			//add it to the list
			tempEmp.setName(tempVal);
			myEmpls.add(tempEmp);
			
		}	
		
	}
 
}
 
---------------------------------
 
package example;
 
public class Narrator {
	
	private String name;
	
	public Narrator(){
		
	}
	
	public Narrator(String name){
		
		this.name=name;
	}
 
	public void setName(String name){
		
		this.name=name;
	}
	
	public String getName(){
		
		return name;
	}
	
	public String toString() {
		StringBuffer sb = new StringBuffer();		
		sb.append("Name:" + getName());
				
		return sb.toString();
	}
}

                                  
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Asked On
2009-10-29 at 22:09:19ID24857140
Tags

Java

,

XML

,

SAX

,

parsing

Topics

JAXP & SAX (XML APIs)

,

New to Java Programming

,

Java Programming Language

Participating Experts
2
Points
500
Comments
4

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Answers

 

by: CEHJPosted on 2009-10-29 at 23:56:23ID: 25700579

Add your Narrator objects to a Set<Narrator>. You will need to implement Narrator.equals based on the name and also implement Narrator.hashCode

 

by: TomasHelgiPosted on 2009-10-30 at 03:20:30ID: 25701541

         Hi!

Here is an example on how to remove duplicates from ArrayList.
http://www.java2s.com/Code/Java/Collections-Data-Structure/RemoveduplicateitemsfromanArrayList.htm

And as CEHJ says you need to implement the methods equals(Object o ) and int hashCode()

Regards,
   Tomas Helgi

 

by: fsyedPosted on 2009-10-30 at 16:57:21ID: 31647866

Thanks very much for your prompt replies, your solutions worked!  

Take care.

 

by: CEHJPosted on 2009-10-31 at 01:38:28ID: 25708894

:-)

20120131-EE-VQP-002

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