XML comparison with xmlunit

I have a problem in comparing xml strings.

My compare function is

public static boolean compareXMLs(String xmlSource, String xmlCompareWith){

XMLUnit.setIgnoreWhitespace(true);
XMLUnit.setIgnoreComments(true);
XMLUnit.setIgnoreAttributeOrder(true);

XMLUnit.setNormalizeWhitespace(true);
XMLUnit.setIgnoreDiffBetweenTextAndCDATA(true);

Diff myDiff = new Diff(xmlSource, xmlCompareWith);
myDiff.overrideDifferenceListener(new IgnoreTextAndAttributeValuesDifferenceListener());
return myDiff.similar();
}

My unit test is

 String xml1 = "<a>f</a>";
 String xml2 = "<a>1</a>";
 assertEquals(true, RestCommonUtility.compareXMLs(xml1, xml2));

 xml1 = "<a></a>";
 xml2 = "<a>1</a>";
 assertEquals(true, RestCommonUtility.compareXMLs(xml1, xml2));

My unit test passed in first assert, but fails in 2nd assert. I set IgnoreTextAndAttributeValuesDifferenceListener but still my 2nd assert fails. Is there any way to solve this problem.? Or is there any other framework could help in these kind of comparison?