I get wrong data while reading an XML

Question

I'm trying to collect data from a huge XML, the structure is the following:

 <Ciutats>
      <Ciutat>
        <Nom>Torremolinos</Nom>
        <Provincia>Malaga</Provincia>
        <Dades>
          <Dada dia='2015-01-18'>
            <TempMax>10.4</TempMax>
            <TempMin>7.0</TempMin>
            <TempAve>8.7</TempAve>
            <VMax>8.0</VMax>
            <VRatxa>28.0</VRatxa>
            <Prec>29.8</Prec>
          </Dada>
          <Dada dia='2015-01-19'>
            <TempMax>13.1</TempMax>
            <TempMin>8.7</TempMin>
            <TempAve>10.9</TempAve>
            <VMax>29.0</VMax>
            <VRatxa>64.0</VRatxa>
            <Prec>6.2</Prec>
          </Dada>
          ....
      </Ciutat>
      <Ciutat>
        <Nom>Valdemorillo</Nom>
        <Provincia>Madrid</Provincia>
        <Dades>
          <Dada dia='2015-01-18'>
            <TempMax>1.7</TempMax>
            <TempMin>-2.2</TempMin>
            <TempAve>-0.3</TempAve>
            <VMax>5.0</VMax>
            <VRatxa>13.0</VRatxa>
            <Prec>1.2</Prec>
          </Dada>
          <Dada dia='2015-01-19'>
            <TempMax>3.6</TempMax>
            <TempMin>0.3</TempMin>
            <TempAve>1.9</TempAve>
            <VMax>41.0</VMax>
            <VRatxa>69.0</VRatxa>
            <Prec>4.0</Prec>
          </Dada>
          ...
  </Ciutat>    
</Ciutat>

for every "Ciutat" you have "Nom" "Provincia" and "Dades" where you have 29 Objects for every city, the XML has 784 cities in total.

And here's my code to read the XML:

    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        File file = new File(fileName);
        Document document = builder.parse(file);

     Element ct = document.getDocumentElement();
        NodeList ciutatList = ct.getElementsByTagName("Ciutat");
        if (ciutatList != null && ciutatList.getLength() > 0) {
            for (int i = 0; i < ciutatList.getLength(); i++) {

                Element ciutats = (Element) ciutatList.item(i);
                NodeList nomList = ciutats.getElementsByTagName("Nom");
                if (nomList != null && nomList.getLength() > 0) {
                    Element nomElement = (Element) nomList.item(0);
                    nom = nomElement.getFirstChild().getNodeValue();
                }

                NodeList provList = ciutats.getElementsByTagName("Provincia");
                if (provList != null && provList.getLength() > 0) {
                    Element provElement = (Element) provList.item(0);
                    prov = provElement.getFirstChild().getNodeValue();
                }

                tc = new TempsCiutat(nom, prov, 1000);

                NodeList dadesList = ct.getElementsByTagName("Dades");
                Element dadesElement = (Element) dadesList.item(0);

                NodeList dadaList = dadesElement.getElementsByTagName("Dada");
                for (int a = 0; a < dadaList.getLength(); a++) {
                    Date data = null;
                    float  tempMax = 0, tempMin = 0, tempAve = 0, VMax = 0, VRatxa = 0, prec = 0;

                    Element dades = (Element) dadaList.item(a);

                    String dataS = dades.getAttribute("dia");
                    data = df.parse(dataS);

                    NodeList tempMaxList = dades.getElementsByTagName("TempMax");
                    if (tempMaxList != null && tempMaxList.getLength() > 0) {
                        Element tempMaxElement = (Element) tempMaxList.item(0);
                        String tempMaxS = tempMaxElement.getFirstChild().getNodeValue();
                        tempMax = Float.parseFloat(tempMaxS);
                    }

                    NodeList tempMinList = dades.getElementsByTagName("TempMin");
                    if (tempMinList != null && tempMinList.getLength() > 0) {
                        Element tempMinElement = (Element) tempMinList.item(0);
                        String tempMinS = tempMinElement.getFirstChild().getNodeValue();
                        tempMin = Float.parseFloat(tempMinS);
                    }
                    NodeList tempAveList = dades.getElementsByTagName("TempAve");
                    if (tempAveList != null && tempAveList.getLength() > 0) {
                        Element tempAveElement = (Element) tempAveList.item(0);
                        String tempAveS = tempAveElement.getFirstChild().getNodeValue();
                        tempAve = Float.parseFloat(tempAveS);
                    }
                    NodeList VmaxList = dades.getElementsByTagName("VMax");
                    if (VmaxList != null && VmaxList.getLength() > 0) {
                        Element VmaxElement = (Element) VmaxList.item(0);
                        String VMaxS = VmaxElement.getFirstChild().getNodeValue();
                        VMax = Float.parseFloat(VMaxS);
                    }
                    NodeList VRatxaList = dades.getElementsByTagName("VRatxa");
                    if (VRatxaList != null  && VRatxaList.getLength() > 0) {
                        Element VRatxaElement = (Element) VRatxaList.item(0);
                        String VRatxaS = VRatxaElement.getFirstChild().getNodeValue();
                        VRatxa = Float.parseFloat(VRatxaS);
                    }
                    NodeList precList = dades.getElementsByTagName("Prec");
                    if (precList != null && precList.getLength() > 0) {
                        Element precElement = (Element) precList.item(0);
                        String precS = precElement.getFirstChild().getNodeValue();
                        prec = Float.parseFloat(precS);
                    }
                    TempsDia dia = new TempsDia(data, tempMax, tempMin, tempAve, VMax, VRatxa, prec);

                    tc.afegirTempsDia(dia);
                }

                tp.afegirCiutat(tc);
            }

        }

Now the problem is that when I read the first city it does it right, but, when it comes to read the second, the name and "Provincia" are correct, but the "Dades" are the same as the first city, I wonder if I have to close the Dada read somehow.

score 1 · Accepted Answer · answered Apr 04 '15 at 19:03

You have the document:

Element ct = document.getDocumentElement();

You get the correct node list for cities:

NodeList ciutatList = ct.getElementsByTagName("Ciutat");

But you get the Dades by

NodeList dadesList = ct.getElementsByTagName("Dades");

which is from the entire document, so you get the first Dades all over again. Instead, iterate the NodeList ciutatList and call

NodeList dades =
  (Element) ciutatList.item(i).getElementsByTagName("Dades");

PS: Why don't you use JAXB?

I realized that a few minutes ago ^^', It's a uni assignment so we have to do it this way, thanks for the answer :) — manutheking, Apr 04 '15 at 19:08

score 0 · Answer 2 · answered Apr 04 '15 at 19:06

Ok, I feel so dumb.

On

NodeList dadesList = ct.getElementsByTagName("Dades");
Element dadesElement = (Element) dadesList.item(0);

it's actually:

NodeList dadesList = ciutats.getElementsByTagName("Dades");
Element dadesElement = (Element) dadesList.item(0);

score 0 · Answer 3 · edited May 23 '17 at 11:43

0

I understand this is a school assignment but maybe have a look at xpath it makes it easier to get to this sort of data.

How to read XML using XPath in Java

edited May 23 '17 at 11:43

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answered Apr 04 '15 at 19:38

Theresa Forster

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I get wrong data while reading an XML

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