Generating xml file with "&" using java

I need to write <name> Dolce & Gabanna </name> in an xml file using java.

No, you don't. Not unless you're trying to create an invalid file. Whatever code you're using is doing exactly the right thing - any XML parser reading the file will then unescape the & to & where appropriate.

From the XML 1.0 specification, section 2.4:

The ampersand character (&) and the left angle bracket (<) must not appear in their literal form, except when used as markup delimiters, or within a comment, a processing instruction, or a CDATA section. If they are needed elsewhere, they must be escaped using either numeric character references or the strings " & " and " < " respectively.