Question

I’ve tried

SAXParserFactory factory = SAXParserFactory.newInstance();
factory.setNamespaceAware(false);
factory.setValidating(false);
XMLReader reader = factory.newSAXParser().getXMLReader();
Source xmlInput = new SAXSource(reader, new InputSource(new StringReader(xml)));
StringWriter stringWriter = new StringWriter();
xmlPretty = new StreamResult(stringWriter);   
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2");
transformer.transform(xmlInput, xmlPretty);
return xmlPretty.getWriter().toString();

but as soon as there is an “ignorable space” the indentation stops. I’ve searched a lot but found nothing about ignorable spaces in sax parsers, except in Handlers. So I’ve tried to add a handler of mine:

class MyHandler extends DefaultHandler {
  @Override
  public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException {
    System.out.println("foo");
  }
}
...
reader.setContentHandler(new MyHandler());

but it never prints “foo”.

Update:
Here is an example of input:

<n:a>  <b>foo </b>  </n:a>

So well-formed but invalid (n is not defined). I want the function to output something like:

<n:a>
  <b>foo </b>
</n:a>

The program above does output this if I provide it with:

<n:a><b>foo </b></n:a>

But not with <n:a> <b>foo </b> </n:a>.

Answer 1

I don’t think the namespace not declared makes any difference, while additional whitespaces do.
I tried your code and, I’m still trying to understand why, if you add this line

transformer.setOutputProperty(OutputKeys.METHOD, "html");

you should have the desired output. Could you confirm this and check for any eventual side effects?