Java and parsing XML

Question

I write application which will be parse XML files. I use SAX parser and here is my SAX handler code:

public class XMLHandler extends DefaultHandler {

private static final String MEASURES = "measures";

private static final String SUGARMEASUREDATE = "sugarMeasureDate";
private static final String SUGARMEASUREVALUE = "sugarMeasureValue";

private static final String UPGYROSCOPEDATE = "upGyroscopeDate";
private static final String UPGYROSCOPEVALUE = "upGyroscopeValue";

private static final String DOWNGYROSCOPEDATE = "downGyroscopeDate";
private static final String DOWNGYROSCOPEVALUE = "downGyroscopeValue";

Boolean currentElement = false;
String currentValue = null;

public static MeasureLists measureLists = null;

public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
    currentElement = true;

    if (localName.equals("measures")) {
        measureLists = new MeasureLists();
    }
}

public void endElement(String uri, String localName, String qName) throws SAXException {

    currentElement = false;
    if (localName.equals(SUGARMEASUREDATE)) {
        measureLists.setSugarDate(currentValue);
    }
    else if (localName.equals(SUGARMEASUREVALUE)) {
        measureLists.setSugarValue(currentValue);
    }
    else if (localName.equals(UPGYROSCOPEDATE)) {
        measureLists.setUpGyroscopeDate(currentValue);
    }
    else if (localName.equals(UPGYROSCOPEVALUE)) {
        measureLists.setUpGyroscopeValue(currentValue);
    }
    else if (localName.equals(DOWNGYROSCOPEDATE)) {
        measureLists.setDownGyroscopeDate(currentValue);
    }
    else if (localName.equals(DOWNGYROSCOPEVALUE)) {
        measureLists.setDownGyroscopeValue(currentValue);
    }
}

public void characters(char[] ch, int start, int length) throws SAXException {

    if (currentElement) {
        currentValue = new String(ch, start, length);
        currentElement = false;
    }
}

public MeasureLists getMeasureLists() {
    return measureLists;
}
}

My problem is that this code detects events (start and end tag) properly but variable localName is empty String. I read in documentation that localName is empty if "Namespace processing is not being performed." My question is what it is mean and how can I handle with it. Thanks for any help and tip.

EDIT

I notice that when I change "localName" variable for "qName" there all things go right and I have no problem. Do you know what it is?

a bigger problem here is the characters method.

Nathan Hughes
– Nathan Hughes

2011-10-12 16:34:53 +00:00
Commented Oct 12, 2011 at 16:34 — Nathan Hughes
– Nathan Hughes, Commented Oct 12, 2011 at 16:34

Varun Achar · Accepted Answer · 2011-10-12 16:38:57Z

4

An XML Namespace contains a 2 part structure, one part is called the URI and the second part is called the localName. E.g. would be

html:va xmlns:html="www.google.com"

Here, the URI is the www.google.com and localName is va. These are specified in the start tags of an XML. In you case, something seems amiss in the namespace of you XML. That might be the reason why you're getting this problem.

More information can be found here:

http://www.saxproject.org/namespaces.html

answered Oct 12, 2011 at 16:38

Varun Achar

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Comments

forty-two · Accepted Answer · 2011-10-12 17:15:34Z

2

My guess is that your XML uses namespaces, but your SAXParser is not configured for namespace processing (in which case the qualified element, 'prefix:localName', is present in the qName parameter). If you use JAXP, set the namespaceAware property on the SAXParserFactory to true. To be really sure that your'e processing the correct elements, you should also check that the uri parameter is what you expect (or should expect).

You also have a problems with the characters method. The caharacters() method may be called more than once for each element, even if the element contain only text. What you need to do is to use a StringBuidler to collect the characters in, and use that in the enedELement method.

edited Oct 12, 2011 at 17:15

answered Oct 12, 2011 at 17:08

forty-two

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