Do you use Javadoc for every method you write?

Question

Should I be writing Doc Comments for all of my java methods?

Answer 1

@Claudiu

When I write code that others will use - Yes. Every method that somebody else can use (any public method) should have a javadoc at least stating its obvious purpose.

@Daniel Spiewak

I thoroughly document every public method in every API class. Classes which have public members but which are not intended for external consumption are prominently marked in the class javadoc. I also document every protected method in every API class, though to a lesser extent. This goes on the idea that any developer who is extending an API class will already have a fair concept of what's going on.

Finally, I will occasionally document private and package private methods for my own benefit. Any method or field that I think needs some explanation in its usage will receive documentation, regardless of its visibility.

@Paul de Vrieze

For things, like trivial getters and setters, share the comment between then and describe the purpose of the property, not of the getter/setter

/** 
 * Get the current value of the foo property.
 * The foo property controls the initial guess used by the bla algorithm in
 * {@link #bla}
 * @return The initial guess used by {@link #bla}
 */
int getFoo() {
  return foo;
}

And yes, this is more work.

@VonC

When you break a huge complex method (because of high cyclomatic complexity reason) into:

• one public method calling
• several private methods which represent internal steps of the public one

, it is very useful to javadoc the private methods as well, even though that documentation will not be visible in the javadoc API files.
Still, it allows you to remember more easily the precise nature of the different steps of your complex algorithm.

And remember: limit values or boundary conditions should be part of your javadoc as well.

Plus, javadoc is way better than simple "//comment":

• It is recognized by IDE and used to display a pop-up when you move your cursor on top of one of your - javadoc-ed - function. For instance, a constant - that is private static final variable -, should have a javadoc, especially when its value is not trivial. Case in point: regexp (its javadoc should includes the regexp in its non-escaped form, what is purpose is and a literal example matched by the regexp)
• It can be parsed by external tools (like xdoclet)

@Domci

For me, if somebody will see it or not doesn't matter - it's not likely I'll know what some obscure piece of code I wrote does after a couple of months. [...]
In short, comment logic, not syntax, and do it only once, on a proper place.

@Miguel Ping

In order to comment something, you have to understand it first. When you trying to comment a function, you are actually thinking of what the method/function/class does, and this makes you be more specific and clear in your javadoc, which in turn makes you write more clear and concise code, which is good.

Answer 2

If the method is, obviously self evident, I might skip a javadoc comment.

Comments like

/** Does Foo */
 void doFoo();

Really aren't that useful. (Overly simplistic example, but you get the idea)

Answer 3

I thoroughly document every public method in every API class. Classes which have public members but which are not intended for external consumption are prominently marked in the class javadoc. I also document every protected method in every API class, though to a lesser extent. This goes on the idea that any developer who is extending an API class will already have a fair concept of what's going on.

Finally, I will occasionally document private and package private methods for my own benefit. Any method or field that I think needs some explanation in its usage will receive documentation, regardless of its visibility.

Answer 4

All bases covered by others already; one additional note:

If you find yourself doing this:

/**
 * This method currently launches the blaardh into the bleeyrg.
 */
void execute() { ... }

Consider changing it into this:

void launchBlaardhIntoBleeyrg() { ... }

This may seem a bit obvious, but in many cases the opportunity is easy to miss in your own code.

Finally keep in mind that the change is not always wanted; for instance the behaviour of the method may be expected to evolve over time (note the word "currently" in the JavaDoc).

Answer 5

For things, like trivial getters and setters, share the comment between then and describe the purpose of the property, not of the getter/setter.

/** 
 * Get foo
 * @return The value of the foo property
 */
int getFoo() {
  return foo;
}

Is not useful. Better do something like:

/** 
 * Get the current value of the foo property.
 * The foo property controls the initial guess used by the bla algorithm in
 * {@link #bla}
 * @return The initial guess used by {@link #bla}
 */
int getFoo() {
  return foo;
}

And yes, this is more work.

Answer 6

No, do not comment every method, variable, class, etc..

Here's a quote from "Clean Code: A Handbook of Agile Software Craftsmanship":

It is just plain silly to have a rule that says that every function must have a javadoc, or every variable must have a comment. Comments like this just clutter up the code, popagate lies, and lend to general confusion and disorganization.

A comment should exist if, and only if, it adds important information for the intended user of the method, variable, class, etc.. What constitutes "important" is worth consideration and could be a reminder to myself when/if I come back to this method/class/etc., a consequence/side effect of the method, motivation for why the thing even exists (in the case where some code is overcoming a shortcoming/bug of some library or system), important information about the performance or when it is appropriate to call, etc..

What is not a good comment but indicates the code itself should be rewritten/modified is a comment explaining the details of a complex and obscure method or function. Instead, prefer shorter clearer code.

Answer 7

When I write code for myself - NO. In this case, java doccing is a waste of my time.

When I write code that others will use - Yes. Every method that somebody else can use (any public method) should have a java doc at least stating its obvious purpose. For a good test - run the javadoc creation utility on your code (I forget the exact command line now). Browse through the webpage it generates. If you would be satisfied using a library with that level of documentation, you're golden. If not, Write more javadocs in your code.

Answer 8

There is another reason you should use javadocs. In order to comment something, you have to understand it first. When you trying to comment a function, you are actually thinking of what the method/function/class does, and this makes you be more specific and clear in your javadoc, which in turn makes you write more clear and concise code, which is good.

Answer 9

Java doc should not be relied on, as it places a burden on developers making changes to maintain the java doc as well as the code.

Class names and function names should be explicit enough to explain what is going on.

If to explain what a class or method does makes its name too long to deal with, the class or method is not focused enough, and should be refactored into smaller units.

Answer 10

simply put: YES

The time you need to think about whether you should write a doc, is better invested in writing a doc.

Writing a one-liner is better than spending time for not documenting the method at all in the end.

Answer 11

For me, if somebody will see it or not doesn't matter - it's not likely I'll know what some obscure piece of code I wrote does after a couple of months. There are a few guidelines:

1. APIs, framework classes, and internal reusable static methods should be commented thoroughly.

2. Logic in every complicated piece of code should be explained on two places - general logic in javadoc, and logic for each meaningful part of code in it's own comment.

3. Model properties should be commented if they're not obvious. For example, no point in commenting username and password, but type should at least have a comment which says what are possible values for type.

4. I don't document getters, setters, or anything done "by the book". If the team has a standard way of creating forms, adapters, controllers, facades... I don't document them, since there's no point if all adapters are the same and have a set of standard methods. Anyone familiar with framework will know what they're for - assuming that the framework philosophy and way of working with it is documented somewhere. In this cases, comments mean additional clutter and have no purpose. There are exceptions to this when class does something non-standard - then short comment is useful. Also, even if I'm creating form in a standard way, I like to divide parts of the form with short comments which divide the code into several parts, for example "billing address starts here".

In short, comment logic, not syntax, and do it only once, on a proper place.

Answer 12

I feel there should at least be comments regarding the parameters accepted and return types in term of what they are.
One can skip the implementation details in case the function names describes it completely, for eg, sendEmail(..);

Answer 13

I make it a point to write javadoc comments whenever it is non-trivial, Writing javadoc comments when using an IDE like eclipse or netbeans isn't that troublesome. Besides, when you write a javadoc comment, you are being forced to think about not just what the method does, but what the method does exactly, and the assumptions you've made.

Another reason is that once you've understood your code and refactored it, the javadoc allows you to forget about what it does since you can always refer to it. I'm not advocating purposely forgetting what your methods do but it's just that I prefer to remember other things which are more important.

Answer 14

Javadoc can be really useful for libraries and reusable components. But let's be more practical. It is more important to have self explaining code than javadoc. If you imagine a huge legacy project with Javadocs - would you rely on that? I do not think so... Someone has added Javadoc, then the implementation has changed, new feature was added (removed), so the Javadoc got obsolete. As I mentioned I like to have javadocs for libraries, but for active projects I would prefer

• small functions/classes with names which describe what they do
• clear unit test cases which give explanation what the function/classes do

Answer 15

You should probably be documenting all of your methods really. Most important are public API methods (especially published API methods). Private methods are sometimes not documented, although I think they should be, just for clarity - same goes with protected methods. Your comments should be informative, and not just reiterate what the code does.

If a method is particularly complex, it is advised that you document it. Some people believe that code should be written clearly so that it doesn't require comments. However, this is not always possible, so comments should be used in these cases.

You can automate the generation of Javadoc comments for getters/setters from Eclipse via the code templates to save on the amount of documentation you have to write. another tip is to use the @{$inheritDoc} to prevent duplication of code comments between interfaces and implementation classes.

Answer 16

Assumed in all the answers so far is that the comments will be good comments. As we all know that is not always the case, sometimes they are even incorrect. If you have to read the code to determine its intent, boundaries, and expected error behavior then the comment is lacking. For example, is the method thread safe, can any arg be null, can it return null, etc. Comments should be part of any code reviews.

This may be even more important for private methods since a maintainer of the code base will have to contend with issues that an API user will not.

Perhaps IDEs should have a feature that allows the use of a documenting form so that the developer can check off various properties that are important and applicable for the current method.

Answer 17

at a previous company, we used to use the jalopy code formatter with eclipse. That would add javadoc to all the methods including private.

It made life difficult to document setters and getters. But what the heck. You have to do it -- you do it. That made me learn some macro functionality with XEmacs :-) You can automate it even further by writing a java parser and commenter like ANTLR creator did several years ago :-)

currently, I document all public methods and anything more than 10 lines.

Answer 18

I try to at the very least document every public and interface property and method, so that people calling into my code know what things are. I also try to comment as much as possible in line as well for maintenance sake. Even 'personal' projects I do on my own time just for myself, I try to javadoc just because I might shelf it for a year and come back to it later.

Answer 19

You can run javadoc against code that does not have javadoc comments and it will produce fairly useable javadocs if you give thoughtful names to your methods and parameters.