从特定标签读取XML文件

Question

I am new to Read an XML File using Java! Actually I want to read Paragraphs under a specific tag sample of XML is:

  <ATTRIBUTE name="Documentation" type="STRING"> </ATTRIBUTE>

  <ATTRIBUTE name="__Variants__" type="LONGSTRING"> </ATTRIBUTE>

  <ATTRIBUTE name="GUID_NPI" type="STRING"> </ATTRIBUTE>

  <ATTRIBUTE name="Status" type="ENUMERATION">None</ATTRIBUTE>

  <ATTRIBUTE name="Order" type="INTEGER">0</ATTRIBUTE>

  <ATTRIBUTE name="Costs" type="DOUBLE">0</ATTRIBUTE>

  <ATTRIBUTE name="Description" type="STRING">CARE management manage manager managing recognised that their capacity to develop developer development developing an insurance       product was limited and they would need to bring in particular expertise. They first       identified an array of basic requirements for the process as a whole: • Understanding of       insurance principles and processes • Experience of microfinance and microfinance clients •       Training skills • Clear vision of the new product development process • Marketing savvy, and       Ability to work with and guide partners that have different backgrounds and motivations.      </ATTRIBUTE>

  <ATTRIBUTE name="Comment" type="STRING"> </ATTRIBUTE>

  <ATTRIBUTE name="External documentation" type="PROGRAMCALL">ITEM "" param:""      </ATTRIBUTE>

  <INTERREF name="Organizational unit"> </INTERREF>

  <ATTRIBUTE name="Info on results" type="STRING"> </ATTRIBUTE>

So i have an xml that contains paragraphs under the following tags

and i want to read the data inside these tags. I have been trying this:

 try {

File fXmlFile = new File("c:\\Data.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);


doc.getDocumentElement().normalize();

System.out.println("Root element :" + doc.getDocumentElement().getNodeName());

NodeList nList = doc.getElementsByTagName("ATTRIBUTE");

System.out.println("----------------------------");

for (int temp = 0; temp < nList.getLength(); temp++) {

    Node nNode = nList.item(temp);

    System.out.println("\nCurrent Element :" + nNode.getNodeName());

    if (nNode.getNodeType() == Node.ELEMENT_NODE) {

        Element eElement = (Element) nNode;

        System.out.println("DATA : "+temp+"  " + eElement.getAttribute("type"));
        System.out.println("PARAGRAPH : " + eElement.getElementsByTagName("ATTRIBUTE").item(0).getTextContent());

    }
}
} catch (Exception e) {
e.printStackTrace();
}

The output I'm getting is not the complete one:

Root element :ADOXML
----------------------------

 Current Element :ATTRIBUTE
 Staff id : STRING
 java.lang.NullPointerException
at javaapplication5.JavaApplication5.main(JavaApplication5.java:53)

my complete output should be a paragraph:

CARE management manage manager managing recognised that their capacity to develop developer development developing an insurance product was limited and they would need to bring in particular expertise. They first identified an array of basic requirements for the process as a whole: • Understanding of insurance principles and processes • Experience of microfinance and microfinance clients • Training skills • Clear vision of the new product development process • Marketing savvy, and Ability to work with and guide partners that have different backgrounds and motivations.

Can somebody help me please reading in the more specific way please thanks in advance!

Answer 1

You are looping through a node-set of ATTRIBUTE elements nList . So you get one of those elements which is in nNode , print it's name, test if it's an Element (it is), cast it to eElement and get it's attribute type successfully.

But then you try to retrieve a node-set of elements named ATTRIBUTE in the context of the eElement :

eElement.getElementsByTagName("ATTRIBUTE")

which does not exist (your element contains just text - a whitespace character, actually), not a node-set of ATTRIBUTE elements.

So then you have a null reference. If you call any method on a null reference you get NullPointerException .

What you probably want to do here is to get eElement.getNodeValue() which will give you the text contents of the tag.