Regular Expression or else?

[An Sush]

I have a input xml and want to generate another output xml taking this xml as an input.
I am trying this approch:
1) I parse the input xml and generate a object of it.
2) I create a template of output xml needed.
3) I parse the template xml and generate the string represntation of the xml.
4) I use Pattern and Matcher to replace the template node values with actual ones.

I have a template xml, with value of nodes substitued as
<name>${name}</name>
I parsed this template xml in java and want to replace all occurances of ${name} based on the object generated from input xml

When I use this in my java class:
Pattern p = Pattern.compile("${name}");
Matcher m = p.matcher(strTemplate); // strTemplate has d template XML parsed
strReturn = m.replaceAll("John");

I am getting the follwing error:
java.util.regex.PatternSyntaxException: Illegal repetition near index 0
${name}

Can you help me in replacing the string ${name} with say John

Also heard using regular expression in a loop or more times is a serious perfomance hit. Can you let me know a better and efficient way to convert one form of xml to other?

[Ulf Dittmer]

Processing XML with regexps is fraught with problems. Is there a particular reason you don't want to use more standard APIs like JAXP/DOM/XPath for the task?
[ June 01, 2007: Message edited by: Ulf Dittmer ]

[Stan James]

I agree that mucking about with tags and attributes is tough in raw String format, but a simple macro replacement ${name} should be ok. Here's a regex I use for exactly that macro pattern. My application allows nested macros so I have to create a new matcher after every replacement

private static final String macroRegEx = "\\$\\{([^\\{]+?)\\}";
 
...
 
Pattern macroPattern = Pattern.compile( macroRegEx, ... );    
Matcher macroMatcher = macroPattern.matcher( result );
while (macroMatcher.find())
{
    do replacement stuff
    macroMatcher = macroPattern.matcher( result );
}

I haven't profiled the performance of this loop because the whole app is satisfactory.

[An Sush]

So wat would be the best way(performance wise) to transform one xml to another. any piece of code wud b highly appreciated.

[Vyas]

Use JAXP or other Java parser libraries

[Ulf Dittmer]

Sushant and Vyas-

You may have missed that we have a policy on screen names here at JavaRanch. Basically, it must consist of a first name, a space, and a last name, and not be obviously fictitious. Since neither of yours conforms with it, please take a moment to change it, which you can do right here.

[Ilja Preuss]

You might want to consider using an existing template engine. We've made good experiences with FreeMarker: http://freemarker.sourceforge.net/