Removing comments from xml file with vtd-xml , delete comment

Question

is there a way to remove the comments from a huge xml file (>200 MB), parsed by vtd-xml ?

Both, comments before the root element

<!-- comment -->
<rootElement>
.
.
.
 </rootElement>

and comments within

<rootElement>
<book>
<!-- comment -->
</book>
</rootElement>

The best solution would be with xPath. I tried

//comment()

which works with DOM but not with vtd-xml

Here is my code for selecting comments

String xPath = "//comment()"
XMLModifier xm = new XMLModifier();
VTDGen vg = new VTDGen();
if (vg.parseFile(fnIn,true)){
       VTDNav vn = vg.getNav();
       xm.bind(vn);
       nodeXpath(xPath,vn);
}

private void nodeXpath(String xPath, VTDNav vn) throws Exception{
    int result;

    AutoPilot ap = new AutoPilot();
    ap.selectXPath(xPath);
    ap.bind(vn);
    while((result = ap.evalXPath())!=-1){
        int p = vn.getText();

        if (p!=-1) {                
            System.out.println(vn.getText() + ", " + vn.toString(p));               
        }
    }
}

But the nothing is printed to screen here.

Is there a way to do that with vtd xml?

Thanks for your help.

You say that the XPath expression doesn't "work" with VTD-XML. Exactly what did you try, and what was the result? Maybe looking at stackoverflow.com/a/22161292/423105 will help you more get to more concrete questions. — LarsH
I know how to use xPath Expressions and the Modifier. I tried //comment() as Expression but it doesn't work. In DOM it selected the correct texts. Maybe there is a possibility with vtd-xml to identify all comments in the document no matter where they are — Kepler
Yes the same //comment() expression should select all comments in VTD-XML. The question then is how you use that to remove them all. Show us your VTD-XML code (the Java, C# or whatever) and maybe we can help you figure out why it didn't work. — LarsH
You mentioned that your code prints nothing to the screen... not even commas? I wouldn't expect it to necessarily print anything from getText(), since the doc for getText() seems to indicate that it returns "the type character data or CDATA", which I don't think includes the content of a comment. A good test would be to print something in every iteration of your while loop before p = vn.getText(), so you'll know whether it's finding the comments at all. — LarsH

LarsH LarsH · Accepted Answer · 2015-08-19T16:36:22

You mentioned that your code prints nothing to the screen... not even commas? I wouldn't expect it to necessarily print anything from getText(), since the doc for getText() seems to indicate that it returns "the type character data or CDATA", which I don't think includes the content of a comment. (Thank you, @vtd-xml-author, for confirming that.)

A good test would be to print something in every iteration of your while loop before p = vn.getText(), so you'll know whether it's finding the comments at all.

If it is finding the comments, I think you'll want to call xm.removeToken(result) on each one.

Removing comments from xml file with vtd-xml , delete comment

1 Answers