Stephen Colebourne's blog: Javadoc coding standards - 0 views
blog.joda.org/...javadoc-coding-standards.html
java javadoc BestPractices documentation design communication
shared by kuni katsuya on 13 Dec 12
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Javadoc coding standards
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explain some of the rationale for some of my choices
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this is more about the formatting of Javadoc, than the content of Javadoc
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Each of the guidelines below consists of a short description of the rule and an explanation
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Write Javadoc to be read as source code
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Making Javadoc readable as source code
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Public and protected
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All public and protected methods should be fully defined with Javadoc
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Package and private methods do not have to be, but may
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benefit from it.
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think of it as internal design documentation when you revisit this code 8 months from now: - based on nothing but your well-chosen ;) package/class/method/variable names, will you recall all of your current design intentions and rationale? likely not - when you hand-off this code to another software engineer, how easy will it be to mostly rtfm? will you have to waste time preparing design/implementation notes specifically for the hand-off? if this is the case because the code is unreadable and not self-guiding and there's not already at least high level design notes in a wiki, you're doing it wrong!
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If a method is overridden in a subclass, Javadoc should only be present if it says something distinct to the original definition of the method
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ie. don't just copy-paste the javadoc from the superclass. that's mindless and pointless monkey work
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Use the standard style for the Javadoc comment
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Do not use '**/' at the end of the Javadoc
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Use simple HTML tags, not valid XHTML
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XHTML adds many extra tags that make the Javadoc harder to read as source code
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Use a single <p> tag between paragraphs
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Place a single <p> tag on the blank line between paragraphs:
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this at least makes the paragraph breaks wysiwygísh and somewhat easier to read
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Use a single <li> tag for items in a list
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place a single <li> tag at the start of the line and no closing tag
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Define a punchy first sentence
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it has the responsibility of summing up the method or class to readers scanning the class or package
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the first sentence should be
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clear and punchy, and generally short
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use the third person form at the start
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Avoid the second person form, such as "Get the foo"
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Use "this" to refer to an instance of the class
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When referring to an instance of the class being documented, use "this" to reference it.
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Aim for short single line sentences
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Wherever possible, make Javadoc sentences fit on a single line
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favouring between 80 and 120 characters
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Use @link and @code wisely
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@link feature creates a visible hyperlink in generated Javadoc to the target
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@code feature provides a section of fixed-width font, ideal for references to methods and class names
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Only use @link on the first reference to a specific class or method
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Use @code for subsequent references.
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This avoids excessive hyperlinks cluttering up the Javadoc
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Never use @link in the first sentence
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Always use @code in the first sentence if necessary
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Adding a hyperlink in that first sentence makes the higher level documentation more confusing
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Do not use @code for null, true or false
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Adding @code for every occurrence is a burden to both the reader and writer of the Javadoc and adds no real value.
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Use @param, @return and @throws
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@param entries should be specified in the same order as the parameters
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@return should be after the @param entries
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followed by @throws.
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Use @param for generics
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correct approach is an @param tag with the parameter name of <T> where T is the type parameter name.
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Use one blank line before @param
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This aids readability in source code.
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Treat @param and @return as a phrase
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They should start with a lower case letter, typically using the word "the". They should not end with a dot. This aids readability in source code and when generated.
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treated as phrases rather than complete sentences
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Treat @throws as an if clause
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phrase describing the condition
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Define null-handling for all parameters and return types
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ideally, if the method in question has any specified/required pre and/or post conditions, they should be noted in the javadoc, not *just* null handling also, there are cleaner ways to design around this type of old school null handling hackage
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methods should define their null-tolerance in the @param or @return
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standard forms expressing this
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"not null"
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"may be null"
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"null treated as xxx"
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"null returns xxx"
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In general the behaviour of the passed in null should be defined
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Specifications require implementation notes
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Avoid @author
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source control system is in a much better position to record authors
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This wastes everyone's time and decreases the overall value of the documentation. When you have nothing useful to say, say nothing!
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likewise with javadoc on things like default constructors /** * Creates an instance of SomeClass */ public SomeClass() {} is equally useless and unnecessarily clutters up the source code
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