plz, stange problem when transfrom document to xml file with jaxp

[jianlong chen]

hi,
I have a dom which parsed from a xml file, now I want to transform it xml file ,the following is my source code:
import org.w3c.dom.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.*;
.......
DOMSource doms=new DOMSource(dom);
File f=new File(file);
StreamResult sr=new StreamResult(f);
TransformerFactory tff =TransformerFactory.newInstance();
Transformer tr=tff.newTransformer();
Properties pr=tr.getOutputProperties();
pr.setProperty(OutputKeys.ENCODING,"GB2312");
pr.setProperty(OutputKeys.INDENT,"yes");
tr.setOutputProperties(pr);
tr.transform(doms,sr);
it will throw a exception when I run it:
javax.xml.transform.TransformerFactoryConfigurationError: Provider org.apache.xalan.processor.TransformerFactoryImpl not found
at javax.xml.transform.TransformerFactory.newInstance(Unknown Source)

what's the matter? pleas help me!!
thanks

[Roseanne Zhang]

You need to put xalan.jar in your classpath if you are using j2sdk1.4.0 or lower.