Determine if a String is XML using Java and Regular Expressions

So again I am posting something I have to do every now and then and have to spend time, each time, to check the pattern or usage etc. for.

Once in a while, in an app that does not do much XML, and therefore is not already using an XML parser of some kind, will need to at the least, determine if a String is XML. With a pretty simple Regular Expression, it is possible using plain old Java and without using any specific XML technology.

I know there are other references out there for doing this, but it is here below as a code sample, for my easy reference and maybe it will help someone else out, who knows. Enjoy.

Are we XML (like) data? :

import java.util.regex.Pattern;
import java.util.regex.Matcher;


public class test {



    /**
     * return true if the String passed in is something like XML
     *
     *
     * @param inString a string that might be XML
     * @return true of the string is XML, false otherwise
     */
    public static boolean isXMLLike(String inXMLStr) {

        boolean retBool = false;
        Pattern pattern;
        Matcher matcher;

        // REGULAR EXPRESSION TO SEE IF IT AT LEAST STARTS AND ENDS
        // WITH THE SAME ELEMENT
        final String XML_PATTERN_STR = "<(\\S+?)(.*?)>(.*?)</\\1>";



        // IF WE HAVE A STRING
        if (inXMLStr != null && inXMLStr.trim().length() > 0) {

            // IF WE EVEN RESEMBLE XML
            if (inXMLStr.trim().startsWith("<")) {

                pattern = Pattern.compile(XML_PATTERN_STR,
                Pattern.CASE_INSENSITIVE | Pattern.DOTALL | Pattern.MULTILINE);

                // RETURN TRUE IF IT HAS PASSED BOTH TESTS
                matcher = pattern.matcher(inXMLStr);
                retBool = matcher.matches();
            }
        // ELSE WE ARE FALSE
        }

        return retBool;
    }



}/**/
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DOM Document – get or extract contained document (or Node) as XML Source

Something I have to do every once in a while, and can never remember how (especially when under some tight deadline, with people standing over my shoulder asking “is it done yet, is it done?” “how much longer?” etc.) is to extract a fragment of one DOM document to get the XML source of the nested or contained document. So I am going to add a note here, for everyone’s easy reference.

First step is to get a Node to be the Root Node of the new Document. Using methods like Document’s getElementsByTagName(String) and Node.getChildNodes(), or using XPathAPIs and CachedXPathAPI class’ selectSingleNode(Node n, String xPath).

Next we can use a StringWriter and a Transformer to covert the Node to XML Source. Better than a rambling explanation, a simple source example should be do the trick. You can use a method something like the nodeToXMLString example below.

  private String nodeToXMLString(Node node) throws TransformerException
  {
    StringWriter sw = new StringWriter();

    Transformer serializer = TransformerFactory.newInstance().newTransformer();
    serializer.transform(new DOMSource(node), new StreamResult(sw));

    return (sw.toString());
  }

Declare and fill a multi dimensional array in Java

This is one of those super simple things I wont use for ever and ever and then when it comes time to use it, I can never remember and have to look at the API again. It makes me angry that I don’t remember it and so it is here now and I (and others maybe) can remember with a click.  

Using a Java String array as an example, the declaration looks like:

 

String[][] myStr = {
{"col-0-row-0","col-1-row-0"},
{"col-0-row-0","col-1-row-0"}
};