Using XPATH to retrieve values from repeating XML nodes

Question

I am new to XML parsing and Java. I am trying to parse an xml using XPATH. The XML looks like this

<Root>
 <AL1>
  <AL1.1>1</AL1.1>
  <AL1.2>1</AL1.2>
  <AL1.3>
    <CX1.1>Bala</CX1.1>
  </AL1.1>
<AL1>
<AL1>
  <AL1.1>2</AL1.1>
  <AL1.2>1</AL1.2>
  <AL1.3>
    <CX1.1>Bala1</CX1.1>
  </AL1.1>
<AL1>
<AL1>
  <AL1.1>3</AL1.1>
  <AL1.2>1</AL1.2>
  <AL1.3>
    <CX1.1>Bala2</CX1.1>
  </AL1.1>
<AL1>
</Root>

I framed the XPATH like this for getting CX1.1 value /AL1/AL1.3/CX1.1/text(). So far I am able to get only the first occurrence if CX1.1.

XPathExpression expr = xpath.compile("/AL1/AL1.3/CX1.1/text()");
result = (String) expr.evaluate(doc.XPathConstants.STRING);

Could you guys please let me know of a way to get all the different values of CX1.1 in a List using XPATH. Any help is greatly appreciated. Thank you.

Mary Grass · Accepted Answer · 2021-01-07 18:45:43Z

1

Firstly, the XML that you have provided is not well-formed, but once well-formed, I would do the following:

  String expression = "//AL1/AL1.3/CX1.1/text()";

        NodeList list = (NodeList) xPath.compile(expression).evaluate(doc, XPathConstants.NODESET);

        List<String> strings = new ArrayList<String>();

        for (int i = 0; i < list.getLength(); i++) {
            strings.add(list.item(i).toString());
        }

Which is to save the result of the xpath query in a NodeList and then iterate over it to save each value in a List<String> with a loop.

answered Jan 7, 2021 at 18:45

Mary Grass

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Comments

kjhughes · Accepted Answer · 2021-01-07 18:45:24Z

First, fix your XML to be well-formed:

The AL1.3 start tags should not be closed with AL1.1 end tags, and
your AL1 start tags should be closed with AL1 end tags, not start tags.

Corrected XML:

<Root>
  <AL1>
    <AL1.1>1</AL1.1>
    <AL1.2>1</AL1.2>
    <AL1.3>
      <CX1.1>Bala</CX1.1>
    </AL1.3>
  </AL1>
  <AL1>
    <AL1.1>2</AL1.1>
    <AL1.2>1</AL1.2>
    <AL1.3>
      <CX1.1>Bala1</CX1.1>
    </AL1.3>
  </AL1>
  <AL1>
    <AL1.1>3</AL1.1>
    <AL1.2>1</AL1.2>
    <AL1.3>
      <CX1.1>Bala2</CX1.1>
    </AL1.3>
  </AL1>
</Root>

Corrected XPath

Then fix your XPath to take into account the Root element,

/Root/AL1/AL1.3/CX1.1/text()

or disregard the heritage of CX1.1 elements altogether:

//CX1.1/text()

Corrected Java

Finally, see Mary Grass's concurrent answer (+1) on how to fix your Java code so that the the given type is a XPathConstants.NODESET, not XPathConstants.STRING.

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