Invalid "self-closing element not allowed" JavaDoc error

Andreas Rieber rieberandreas at
Thu Jul 25 18:55:10 UTC 2013

Hi, the documents are HTML 4. I checked a sample with w3c validator and 
there i get only a warning (not an error).

Warning Line 180, Column 4: NET-enabling start-tag requires SHORTTAG YES



The sequence <FOO /> can be interpreted in at least two different ways, 
depending on the DOCTYPE of the document. For HTML 4.01 Strict, the '/' 
terminates the tag <FOO (with an implied '>'). However, since many 
browsers don't interpret it this way, even in the presence of an HTML 
4.01 Strict DOCTYPE, it is best to avoid it completely in pure HTML 
documents and reserve its use solely for those written in XHTML.

Standalone tags like <br />, <img />, <input /> .... are XHTML.

Warning or error, hard to decide? I would also assume warning.


On 25.07.13 20:13, David M. Lloyd wrote:
> It all hinges on whether the tool is generating HTML 4 or HTML 5.  If 4,
> then the output should be HTML 4 "strict" and this kind of input should
> either be translated or forced to be valid.
> If the output is going to be HTML 5 - which I suspect is going to be
> considered "premature" given the usual glacial pace of these kinds of
> changes - then perhaps it's time to revisit some other crustiness, like
> the use of frames.
> On 07/25/2013 12:59 PM, Stephen Colebourne wrote:
>> Its complicated, see for example:
>> The key point here is not whether its in the standard or not, but what
>> people actually *do*.
>> There is no doubt in my mind that <br /> br space slash is very common
>> indeed. Its certainly my default. The javadoc validator should be as
>> lenient as browsers are in this case.
>> Stephen
>> On 25 July 2013 18:41, David M. Lloyd <david.lloyd at> wrote:
>>> On 07/25/2013 12:27 PM, Nick Williams wrote:
>>>> My apologies if this is not the right place to address this. If so,
>>>> please
>>>> forgive and direct me to the correct list.
>>>> There are a lot of people/projects complaining about Java 8's new
>>>> "self-closing element not allowed" error when compiling JavaDoc that
>>>> has
>>>> legal <br /> tags in it (just google "self-closing element not
>>>> allowed" in
>>>> quotes). Some (including myself) are asking, "Why should we fix
>>>> this? The
>>>> problem is not in the JavaDoc, it's in the JavDoc compiler." However, I
>>>> haven't been able to find anyone who has actually broached the
>>>> subject on
>>>> any mailing lists.
>>>> <br /> is completely legal. While it is not strictly required by the
>>>> HTML
>>>> standard (unless you're using XHTML), using self-closing tags is
>>>> /preferred/
>>>> because it's more obvious what the intention is. Perhaps most
>>>> importantly,
>>>> <br /> is supported on 100% of browsers and is used throughout
>>>> JavaDoc all
>>>> over the place. I have a feeling that once more projects start
>>>> compiling on
>>>> a released Java 8, this is going to make a fair number of people
>>>> angry that
>>>> hey have to "fix" (read: needlessly change) potentially thousands of
>>>> classes' worth of JavaDoc.
>>>> What was the motivation behind the new "self-closing element not
>>>> allowed"
>>>> check and how can we make it go away?
>>> Not really having a stake in this, I just want to observe a couple
>>> things.
>>> First, from what I can see, the HTML 4.x specifications make no
>>> reference to
>>> self-closing elements or their syntactical realization.  As far as I can
>>> tell (not being any kind of SGML expert), self-closing elements are not
>>> valid or meaningful HTML according to its SGML definition.
>>> Finally, even if they were allowed, the BR tag is explicitly defined to
>>> forbid an end tag; self-closing elements imply an end tag (at least
>>> they do
>>> in XML, which appears to be the next-nearest concrete specification
>>> that has
>>> anything to say on the matter).
>>> See for more info.
>>> So I'm curious when you say "using self-closing tags is /preferred/",
>>> do you
>>> have any sources to cite?
>>> --
>>> - DML

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