The JLS first edition, section 18.3 says:
The first sentence of each documentation comment should be
a summary sentence. This sentence ends at the first period
that is followed by a blank, tab, or line terminator.
It doesn't care if the next letter is upper or lowercase.
(We infer that this rule was intended to apply only to languages
for which period is a sentence terminator.)
This is demonstrated in the following processMouseEvent method in
javax.swing.MenuElement, where the above rule would interpret the
first sentence to be "Process a mouse event":
Process a mouse event. event is a MouseEvent with source being the
receiving element's component. path is the path of the receiving
element in the menu hierarchy including the receiving element itself.
manager is the MenuSelectionManager for the menu hierarchy.
(In my opinion, starting the second and third sentences with lowercase
words is poorly-constructed (but understandable) English.
They should be rewritten so as not to begin with lowercase letters.
But that aside...)
The engineer for BreakIterator is Rich Gillam (###@###.###).
Atul and I tested Rich Gillam's fixes to bugs in 4158381, and
they are fixed. However, we discovered the BreakIterator follows
this rule (which differs from the above rule):
If a period is followed by white space and then a lowercase letter
(or digit), it is not considered the end of a sentence.
See "Comments" for the exact rules that BreakIterator uses.
This rule would interpret the entire processMouseEvent paragraph
shown above to be treated as one sentence.
For this reason, we are not using BreakIterator for English,
while we are for all other languages.
Does it make sense to keep it this way? Is there an upcoming change
to BreakIterator to allow it to work with Javadoc in English?
Neal, I'm just passing this bug on to you, for you to be aware of.
You can close it out if you feel nothing should be done, or
we could talk to the java.text people if we want to do more
research into it.
This should, indeed, be fixed. To help people migrate their doc comments
to the new definition, I would have javadoc emit a warning when the new
interpretation of the first sentence differs from the old interpretation
of the first sentence.
This RFE has been implemented. Location of implementation:
This RFE has been implemented. Javadoc now has two modes for computing the end of the first English sentence. The default is the old behavior but it generates a new warning when the new behavior would be different. The new behavior uses BreakIterator and is enabled by a new command-line flag called -breakiterator.
The main differences are (1) we would now accept a sentence ending in a question mark (which some people find useful in the synopsis of a boolean-returning method), and (2) We would NOT accept a period followed by a lower case letter as ending a sentence, which would allow you to use abbreviations in the first sentence.
It's not major, but people have complained. Fixing this is ultimately a code simplification because English would be treated the same as other languages.
We would hope to make the new mode the default in the next (Tiger) version of javadoc.