Coding Standards

This document describes a list of coding conventions that are required for code submissions to the project. By default, the coding conventions for most Open Source Projects should follow the existing coding conventions in the code that you are working on. For example, if the bracket is on the same line as the if statement, then you should write all your code to have that convention.

If you commit code that does not follow these conventions, you are responsible for also fixing your own code.

Below is a list of coding conventions that are specific to Apache Portals, everything else not specificially mentioned here should follow the official Sun Java Coding Conventions.

1. Brackets should begin and end on a new line and should exist even for one line statements. Examples:

if (foo)
{
    // code here
}

try
{
    // code here
}
catch (Exception bar)
{
    // code here
}
finally
{
    // code here
}

while (someCondition)
{
    // code here
}

2. Though it's considered okay to include spaces inside parens, the preference is to not include them. Both of the following are okay:

if (foo)

or

if ( foo )

3. 4 space indent. NO tabs. Period. We understand that many developers like to use tabs, but the fact of the matter is that in a distributed development environment where diffs are sent to the mailing lists by both developers and the version control system (which sends commit log messages), the use tabs makes it impossible to preserve legibility.

In Emacs-speak, this translates to the following command:

(setq-default tab-width 4 indent-tabs-mode nil)

4. Unix linefeeds for all .java source code files. Other platform specific files should have the platform specific linefeeds.

5. JavaDoc MUST exist on all methods. If your code modifications use an existing class/method/variable which lacks JavaDoc, it is required that you add it. This will improve the project as a whole. For guidelines on how to write proper JavaDocs, see Sun's guidelines

6. When writing javadocs for variables, try to keep the comment on just one line.

/** Documentation of this variable */
private int myVariable;

/**
 * If the documentation of the variable is enough to occupy multiple
 * lines, then this form of comment is also perfectly acceptable.
 */
private int myVariable;

7. The Apache License MUST be placed at the top of each and every file.

8. If you contribute to a file (code or documentation), add yourself to the authors list at the top of the file. You should add yourself to the end of the list of authors. For java files the preferred Javadoc format is:

@author <a href="mailto:user@domain.com">John Doe</a>

9. All .java files should have a @version tag like the one below.

@version $Id: code-standards.xml,v 1.1 2004/03/26 00:18:16 taylor Exp $

10. Import statements must be fully qualified for clarity.

import java.util.ArrayList;
import java.util.Hashtable;

import org.apache.foo.Bar;
import org.apache.bar.Foo;

And not

import java.util.*;
import org.apache.foo.*;
import org.apache.bar.*;

11. Import statements should be listed in alphabetical order. Use blank lines to seperate products. In cases where there is a large number of imports from a single product (like java.x) consider seperating at the second level. For example, you could group all of the java.util, java.swing, etc...

12. The conditional part of if and while statements should not use the equality operator for testing true or false values.

if (foo)

and not

if (foo==true)

13. Always use the short form of the classname in code. Certain exception do apply where the fully qualified classname is required such as when java.sql.Date and java.util.Date are used in the same class. Otherwise, you should always import the class and use the short name.

try
{
}
catch (IOException e)
{
}

and not

try
{
}
catch (java.io.IOException e)
{
}

14. Avoid using Iterators that are initialized outside of the loop.

for (Iterator iter=getIterator(); iter.hasNext; )
{
}

and not

Iterator iter=getIterator();
for (;iter.hasNext; )
{
}

X/Emacs users might appreciate this in their .emacs file.

(defun apache-jakarta-mode ()
  "The Java mode specialization for Apache Jakarta projects."
  (if (not (assoc "apache-jakarta" c-style-alist))
      ;; Define the Apache Jakarta cc-mode style.
      (c-add-style "apache-jakarta" '("java" (indent-tabs-mode . nil))))

  (c-set-style "apache-jakarta")
  (c-set-offset 'substatement-open 0 nil)
  (setq mode-name "Apache Jakarta")

  ;; Turn on syntax highlighting when X is running.
  (if (boundp 'window-system)
      (progn (setq font-lock-support-mode 'lazy-lock-mode)
             (font-lock-mode t))))

;; Activate Jakarta mode.
(if (fboundp 'jde-mode)
    (add-hook 'jde-mode-hook 'apache-jakarta-mode)
  (add-hook 'java-mode-hook 'apache-jakarta-mode))

Thanks for your cooperation.