Reading a value from XML node.

Droid_Coder · November 10th, 2011, 05:57 AM

I'm writing an app that makes an http request to my website and it returns a XML result set that looks like the following:

<ResultSet version="1.0">
<Status>
<code>0</code>
<message>Success</message>
<found>1</found>
</Status>
<Result>
<id>1115550003</id>
<distance>0.00</distance>
<compatibility>100</compatibility>
</Result>
</ResultSet>

I'm trying to read the <code> value but I'm having no luck. I can read the <message> value successfully and place that into a private string variable, but when I try to read the <code> value in the same manner, the getNodeValue() call is returning null. Below is my code...

Code:

    public boolean xmlGetStatus(String response)
        {
        try
            {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document doc = db.parse(new InputSource(new StringReader(response)));

            NodeList resultNodes = doc.getElementsByTagName("Status");           
            Node resultNode = resultNodes.item(0);           
            NodeList attrsList = resultNode.getChildNodes();

            boolean result = false;
            for (int i=0; i < attrsList.getLength(); i++)
                {
                Node node = attrsList.item(i);               
                Node firstChild = node.getFirstChild();
                // Check the error code and return True or False
                if ("code".equalsIgnoreCase(node.getNodeName()) && firstChild!=null)
                    {
                    if ("0".equalsIgnoreCase(firstChild.getNodeValue())
                        {
                        result = true;
                        }
                    }
                // Also, stuff the ErrorMessage into a variable we can use later if need be.
                if ("message".equalsIgnoreCase(node.getNodeName()) && firstChild!=null)
                    {
                    sXmlError = firstChild.getNodeValue();
                    }
                }

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

        return false;
        }

Droid_Coder · November 10th, 2011, 06:15 AM

Actually the posted code does work now. I found a typo in the code and once I fixed it I got the results I expected.

However, I found I that to get this parsing of the <code> value to work I needed to treat the value as a string and use the following code to compare the value.

Code:

                    if ("0".equalsIgnoreCase(firstChild.getNodeValue()))
                        {
                        result = true;
                        }

What I wanted to do was to was to convert to an Integer and then check the value. But using Integer.getInteger(firstChild.getNodeValue()) resulted in a null pointer exception and I'm not sure why.

jiminaus · November 11th, 2011, 12:04 AM

I'm a bit rustly on the XML DOM. I remember that element nodes don't have a value and that you need to get the value of the text node that will be the child of the element node.

Droid_Coder · November 15th, 2011, 04:28 AM

Thanks for the input. Turns out the only change I needed to make was to use Integer.parseInt instead of Integer.getInteger. This allowed me to convert the value from the XML file to an actual Integer value.

alostpacket · November 15th, 2011, 12:28 PM

Integer.parseInt and Integer.valueOf should both work.

valueOf works for almost any object you need to convert to. So like String.valueOf(Object) etc...

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