search an element in a string using Pattern and matcher in Java

Question

I am trying to search an element in a string using Pattern and matcher in Java.

i have a node variant-items and need to get all the characters coming between these nodes. i tried the below regex but it is skipping this line altogether. however if i search using the same regex in Notepad++ i am getting the desired resulted selected. please advice.

<variant-items>((.|\n)*)</variant-items>

Below is my implemenation

String patternSourceComponent = "<variant-items>((.|\n)*)</variant-items>";
            String result=this.isMatched(patternSourceComponent, xml);

public String isMatched(String patternSourceComponent,String xml)
    {
    String varientItem="";
    try{    Pattern patternComponent = Pattern.compile(patternSourceComponent);
            Matcher matcherComponent = patternComponent.matcher(xml);

            System.out.println("matcherComponent Find : "+matcherComponent.find());
           while (matcherComponent.find()) {
               varientItem=matcherComponent.group(0).trim();
               System.out.println("varientItem : "+varientItem);
           }   }
            catch (Exception e)
            {
            System.out.println("Exception : "+e);
            }

    return varientItem;
    }

you need to escape some characters while using in java '\' is one of them — Sanjeev, Feb 17 '14 at 16:32
You shouldn't parse XML with regular expressions ( http://stackoverflow.com/a/1758162/896588 ), use a proper XML parser like JDOM instead. — André Stannek, Feb 17 '14 at 16:32

Rudi Kershaw · Answer 1 · 2015-02-22T13:26:48.610

I would personally use Java DOM to checks your nodes. Using regex for XML is a nightmare, and any code attempting it is very likely to break in the future. Try something like this to get the string contents of your 'variant-items' nodes.

File xmlFile = new File("your_xml.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(xmlFile);

NodeList nList = doc.getElementsByTagName("variant-items");
for (int i = 0; i < nList.getLength(); i++) {
    Node node = nList.item(i);
    System.out.println(node.getNodeValue()); 
}

The above code prints the values of all 'variant-items' nodes in an xml file.

If resources/speed considerations are an issue (like when your_xml.xml is huge), you might be better off using SAX, which is faster (a little more code intensive) and doesn't store the XML in memory.

in the above i am already using a parser to parse and then convert it into a String. my requirement is to find if this regular expression is present in the String variable i get. — Ajay Muraleedharan, Feb 18 '14 at 09:44
@AjayMuraleedharan - If that's the case, why don't you check with your parser **before** you convert it to a string? — Rudi Kershaw, Feb 18 '14 at 11:05

search an element in a string using Pattern and matcher in Java

1 Answers1