How to Generalize the code?

[Farakh khan]

Hello,


I am repeating code every time that looks odd and also if there are 100 elements then a long document. How can I generalize the following code?

	  	XPath xpath = XPathFactory.newInstance().newXPath();
   
		XPathExpression expr = xpath.compile("//parent::*");
		Object result = expr.evaluate(doc, XPathConstants.NODESET);
    		NodeList nodes = (NodeList) result;
		
		
		out.println("<form action=/servlet/DisplayCV method=post>"+
				"<center><table border=0 >");    				

		expr = xpath.compile("//parent::Objectives/text()");
    		result = expr.evaluate(doc, XPathConstants.NODESET);
  		nodes = (NodeList) result;
		for (int i = 0; i < nodes.getLength(); i++) {
		objectives = nodes.item(i).getNodeValue()+"\n";		 
 		}

Thanks & best regards

[Matthew Brown]

Firstly, there seems to be a consistent error in your code. Take the first loop. You are assigning the text you get out of each node to the same variable. In other words, only the final value is kept, and the rest are thrown away. Is that really what you want? I would expect that either you should be adding them to a list, or at the least appending them all.

Once you've fixed that, you're right - you can factor out the bits that are the same into a method, with arguments for those things that are different in each case and those things that need to be passed in. For instance, something like:

    objectives = extractValues(xpath, doc, "Objectives");

    ...

private static String extractValues(XPath xpath, Document doc, String nodeName) {
   // Put the repeated code here, using nodeName to form the XPath expression
}

[Rob Spoor]

The common parts are these:

expr = xpath.compile(XXX);   
result = expr.evaluate(doc, XPathConstants.NODESET);   
nodes = (NodeList) result;    
for (int i = 0; i < nodes.getLength(); i++) {   
    XXXX = nodes.item(i).getNodeValue();          
}

So turn that into a method, with doc and the XPath expression as parameters and the node value as the return value:

private String getValue(Document doc, String query, XPath xpath)
{
    XPathExpression expr = xpath.compile(query);   
    Object result = expr.evaluate(doc, XPathConstants.NODESET);
    nodes = (NodeList) result;
    // you were always assigning just the last one
    int length = nodes.getLength();
    return (length == 0 ? null : nodes.item(length - 1).getNodeValue());
}

objectives = getValue(doc, "//parent::Objectives/text()", xpath) + "\n";
titleName = getValue(doc, "//parent::TitleName/text()", xpath);

I've chosen to also include the XPath object as a parameter to avoid having to recreate it each time.

[Farakh khan]

Matthew Brown wrote:Firstly, there seems to be a consistent error in your code. Take the first loop. You are assigning the text you get out of each node to the same variable. In other words, only the final value is kept, and the rest are thrown away.
Is that really what you want? I would expect that either you should be adding them to a list, or at the least appending them all.

No not at all.

Once you've fixed that, you're right

Actually this is the first time I am working with XPath API. Please correct me where I am wrong that'll be your kind enough


Best regards & thanks for helping

[Farakh khan]

Hello,

Thanks for your reply.

Its throwing following errors:

C:\Program Files (x86)\Java\Tomcat7.2\webapps\ROOT\WEB-INF\classes>javac *.java
UploadManager.java:123: error: cannot find symbol
                nodes = (NodeList) result;
                ^
  symbol:   variable nodes
  location: class UploadManager
UploadManager.java:125: error: cannot find symbol
                int length = nodes.getLength();
                             ^
  symbol:   variable nodes
  location: class UploadManager
UploadManager.java:127: error: cannot find symbol
                return (length == 0 ? null : nodes.item(length - 1).getNodeValue
());
                                             ^
  symbol:   variable nodes
  location: class UploadManager
UploadManager.java:172: warning: BASE64Encoder is internal proprietary API and m
ay be removed in a future release
                String encodedString = new sun.misc.BASE64Encoder().encode(fileC
ontent); // changes done.
                                                   ^
3 errors
1 warning

Best regards

[Matthew Brown]

You need to declare nodes within the method, so that it's in scope when you try to use it.

[Farakh khan]

Thanks Matthew. Now its compiled and working fine. How will I deal with this:

<SegrigatedEducation>
<EducationSplit>
      <University>LUMS Institute of Technology</University>
      <Degree>Master of Computer Science</Degree>
      <Year>Feb 2008 - May 2010</Year>
    </EducationSplit>
</SegrigatedEducation>

expr = xpath.compile("//parent::EducationSplit/*/text()");
    		result = expr.evaluate(doc, XPathConstants.NODESET);
  		nodes = (NodeList) result;
		for (int i = 0; i < nodes.getLength(); i++) {
		education+=nodes.item(i).getNodeValue()+"\n";	 
		}
		

Thanks again for helping