Q:

Any Method to bypass the -- in Comment of HTML

I am using DocumentBuilder to convert xhtml(xml) from the internet which contains "--" in comment to org.w3c.dom. Document.  Are there may method to bypass it?  I have already set the setIgnoringComments and setValidating.  
I know -- is not permitted to appear within comments in XML in W3C specification.  related posts.  
Any suggestions to preprocess XML before convention? 
public static Document convertXmlStrToDocument(String xml) throws ParserConfigurationException, SAXException, IOException{
    DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
    documentBuilderFactory.setIgnoringComments(true);
    documentBuilderFactory.setValidating(false);
    DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
    Document document = documentBuilder.parse(new ByteArrayInputStream(xml.getBytes()));
    return document;
}

It throw exception:
org.xml.sax. SAXParseException; lineNumber: 914; columnNumber: 17; The string "--" is not permitted within comments. 
    at org.apache.xerces.parsers. DOMParser.parse(Unknown Source)
    at org.apache.xerces.jaxp. DocumentBuilderImpl.parse(Unknown Source)
    at javax.xml.parsers. DocumentBuilder.parse(DocumentBuilder.java:121)
    at com.techoffice.util. XmlUtil.convertXmlStrToDocument(XmlUtil.java:41)
    at com.techoffice.util. XmlUtil.evaluateXpath(XmlUtil.java:46)
    at com.techoffice.jc.horse.service.web. ResultWebService.raceDateSelect(ResultWebService.java:41)
    at com.techoffice.jc.horse.service.web. ResultWebServiceTest.retrieveXml(ResultWebServiceTest.java:35)
    at sun.reflect. NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect. NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect. DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect. Method.invoke(Method.java:497)
    at org.junit.runners.model. FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model. ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model. FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements. InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements. RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements. RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements. SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners. ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    at org.junit.runners. ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners. ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners. ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners. ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners. ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements. RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements. RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners. ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.eclipse.jdt.internal.junit4.runner. JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner. TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner. RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner. RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner. RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner. RemoteTestRunner.main(RemoteTestRunner.java:192)

A:

No, the string "--" must not appear within an XML comment:

For compatibility, the string " -- " (double-hyphen) must not occur
  within comments. 

This is not configurable.   Anything's hackable, but you'll be going against the grain and without XML parser support.   Not recommended. 
Try HTML Tidy to clean-up the HTML first.   There is also a Java version of HTML Tidy.