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Editorial Team
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Asked: 2026-05-14T00:36:23+00:00

I have an understanding problem of how the following code works: XMLInputFactory xif =

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I have an understanding problem of how the following code works:

XMLInputFactory xif = XMLInputFactory.newFactory();
XMLOutputFactory xof = XMLOutputFactory.newFactory();

XMLEventReader reader = xif.createXMLEventReader(/* ... */);
XMLEventWriter writer = xof.createXMLEventWriter(/* ... */);

writer.add(reader);

The method writer.add([some reader]) reads all events from reader and writes them consequently. Sadly, following happens:

The input

<root><c/></root>

gets transformed to

<root><c><c/></root>

I know, from XML point of view, these are equal trees, but not for a human 😉

What can I do to get the same output?

FYI: I need a XMLEvent[Reader|Writer] pair later to filter “XML events”.

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1 Answer

  1. Editorial Team

    According to the list of XMLEvents it seems like there is no way to make the distinction and it will indeed generate a StartElement and EndElement event. The consumer would need to optimize for the case when a StartElement is immediately followed by an EndElement.

    This is apparently not the case of the XMLEventReader returned by the factory. If you want to optimize this behavior yourself, I see no other way than to do something like

    • check what’s the concrete XMLEventReader implementation returned by createXMLEventReader
    • subclass the XMLEventReader implementation to optimize this case
    • subclass XMLInputFactory and override createXMLEventReader to return an instance of your XMLEventReader subclass

    If this sounds too complicated (or doesn’t work), I would suggest that you go with a solution that uses XMLStreamWriter. This one has a dedicated method writeEmptyElement.

    (Or you can give a try to my home-made pretty printer, it’s based on XMLStreamWriter)

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