Author: buildbot
Date: Thu Apr 19 09:17:30 2012
New Revision: 813629
Log:
Staging update by buildbot for ace
Modified:
websites/staging/ace/trunk/content/ (props changed)
websites/staging/ace/trunk/content/dev-doc/coding-standards.html
Propchange: websites/staging/ace/trunk/content/
------------------------------------------------------------------------------
--- cms:source-revision (original)
+++ cms:source-revision Thu Apr 19 09:17:30 2012
@@ -1 +1 @@
-1327872
+1327884
Modified: websites/staging/ace/trunk/content/dev-doc/coding-standards.html
==============================================================================
--- websites/staging/ace/trunk/content/dev-doc/coding-standards.html (original)
+++ websites/staging/ace/trunk/content/dev-doc/coding-standards.html Thu Apr 19
09:17:30 2012
@@ -153,6 +153,69 @@
<h1>Coding Standards</h1>
<div class="clear"></div>
<div id="content"><p>This is a Java coding style guide for the Apache
ACE project.</p>
+<div class="toc">
+<ul>
+<li><a href="#summary">Summary</a></li>
+<li><a href="#class-layout-and-comments">Class layout and comments</a><ul>
+<li><a href="#files-and-filenames">Files and filenames</a><ul>
+<li><a href="#file-names">File names</a></li>
+<li><a href="#file-organization">File organization</a></li>
+<li><a href="#beginning-comments">Beginning comments</a><ul>
+<li><a href="#package-and-import-statements">Package and import
statements</a></li>
+<li><a href="#class-interface-enum-and-annotation-declarations">Class,
interface, enum and annotation declarations</a></li>
+<li><a href="#annotations">Annotations</a></li>
+</ul>
+</li>
+</ul>
+</li>
+<li><a href="#indentation">Indentation</a><ul>
+<li><a href="#line-length">Line length</a></li>
+<li><a href="#wrapping-lines">Wrapping lines</a></li>
+</ul>
+</li>
+<li><a href="#comment">Comment</a><ul>
+<li><a href="#comment-styles">Comment styles</a><ul>
+<li><a href="#single-line-comments">Single line comments</a></li>
+<li><a href="#block-comments">Block comments</a></li>
+<li><a href="#javadoc-comments">JavaDoc comments</a><ul>
+<li><a href="#html-tags">HTML tags</a></li>
+</ul>
+</li>
+</ul>
+</li>
+</ul>
+</li>
+</ul>
+</li>
+<li><a href="#java-syntax-and-its-layout">Java syntax and its layout</a><ul>
+<li><a href="#declarations">Declarations</a><ul>
+<li><a href="#number-per-line">Number per line</a></li>
+<li><a href="#placement">Placement</a></li>
+<li><a href="#initialization">Initialization</a></li>
+<li><a href="#class-and-interface-declarations">Class and Interface
Declarations</a></li>
+</ul>
+</li>
+<li><a href="#statements">Statements</a><ul>
+<li><a href="#simple-statements">Simple statements</a></li>
+<li><a href="#compound-statements">Compound statements</a></li>
+<li><a href="#if-if-else-if-else-if-else-statements">if, if-else, if else-if
else statements</a></li>
+<li><a href="#switch">switch</a></li>
+<li><a href="#try-catch">try - catch</a></li>
+<li><a href="#for-loops">for loops</a></li>
+</ul>
+</li>
+<li><a href="#white-space">White Space</a><ul>
+<li><a href="#blank-lines">Blank lines</a></li>
+<li><a href="#blank-spaces">Blank spaces</a></li>
+</ul>
+</li>
+<li><a href="#namingconventions">Naming conventions</a></li>
+</ul>
+</li>
+<li><a href="#downloads">Downloads</a></li>
+<li><a href="#references">References</a></li>
+</ul>
+</div>
<h2 id="summary">Summary</h2>
<p>This style guide is intended to help the computer professional produce
better Java programs. It presents a set of specific guidelines for using the
features of Java in a disciplined manner. The goal is to develop high quality,
reliable, reusable, portable software. For a number of reasons, no programming
language can ensure the achievements of these desirable objectives on its own.
Programming must be embedded in a disciplined development process that
addresses a number of topics in a well managed way. The use of Java is one of
those. It must conform to good programming practice based on well established
software engineering principles. This style guide is intended to bridge the gap
between these principles and the actual practice of programming in Java.</p>
<p>Clear, readable, understandable source text eases program evolution,
adaptation and maintenance. First, such source text is more likely to be
correct and reliable. Second, effective code adaptation is a prerequisite to
code reuse, a technique that has the potential for drastic reductions in system
development costs. Easy adaptation requires thorough understanding of the
software, and that is facilitated considerably by clarity. Finally, since
maintenance (really evolution) is a costly process that continues throughout
the life of a system, clarity plays a major role in keeping maintenance costs
down. Over the entire life cycle, code has to be read and understood far more
often than it is written; the investment of effort in writing readable,
understandable code is thus well worthwhile. Many of the guidelines in this
style guide are designed to promote clarity of the source text.</p>
@@ -175,26 +238,26 @@
<p>Beginning comments are used for licensing and copyright information only.
Here at Apache, we embed the ASL 2.0 headers at the top of every file. Note
that they are not according to the JavaDoc style (See: How to write doc
comments for JavaDoc - Sun Microsystems, Inc.).</p>
<h5 id="package-and-import-statements">Package and import statements</h5>
<p>The first non-comment line of most Java source files is a package
statement. After an empty line import statements can follow. For example:</p>
-<div class="codehilite"><pre><span class="nb">package</span> <span
class="n">org</span><span class="o">.</span><span class="n">apache</span><span
class="o">.</span><span class="n">ace</span><span class="o">.</span><span
class="n">core</span><span class="o">.</span><span class="n">ui</span><span
class="p">;</span>
+<div class="codehilite"><pre><span class="kn">package</span> <span
class="n">org</span><span class="o">.</span><span class="na">apache</span><span
class="o">.</span><span class="na">ace</span><span class="o">.</span><span
class="na">core</span><span class="o">.</span><span class="na">ui</span><span
class="o">;</span>
-<span class="nb">import</span> <span class="n">java</span><span
class="o">.</span><span class="n">awt</span><span class="o">.</span><span
class="n">Frame</span><span class="p">;</span>
-<span class="nb">import</span> <span class="n">java</span><span
class="o">.</span><span class="n">io</span><span class="o">.</span><span
class="n">InputStream</span><span class="p">;</span>
+<span class="kn">import</span> <span class="nn">java.awt.Frame</span><span
class="o">;</span>
+<span class="kn">import</span> <span
class="nn">java.io.InputStream</span><span class="o">;</span>
</pre></div>
<p>A few notes must be made here:</p>
<ol>
-<li><em>Package rules.</em> When not using an explicit package statement in
your code the code still is in a package, the default package. This easily
results in name clashes and as package naming should be a part of the design,
always use an explicit package name. For naming rules of packages see [naming
conventions|#namingconventions].</li>
-<li><em>Import statements</em> need to be explicit in order to overcome name
clashes. They must be grouped by name.</li>
+<li><em>Package rules.</em> When not using an explicit package statement in
your code the code still is in a package, the default package. This easily
results in name clashes and as package naming should be a part of the design,
always use an explicit package name. For naming rules of packages see <a
href="#namingconventions">naming conventions</a>;</li>
+<li><em>Import statements</em> need to be explicit in order to overcome name
clashes. They must be grouped by name;</li>
<li><em>Import order.</em> First in this section should be the standard Java
imports like: java.lang.Throwable. Second should be the Java extensions (i.e.
javax), third, the third party stuff. Finally the project-specific imports
should be added.</li>
</ol>
<h5 id="class-interface-enum-and-annotation-declarations">Class, interface,
enum and annotation declarations</h5>
<p>The following comment block is an example for the comment that belongs to
the declaration of a class, interface, enum or annotation. The JavaDoc syntax
results in the following block:</p>
-<div class="codehilite"><pre><span class="o">/**</span>
- <span class="o">*</span> <span class="n">Configuration</span> <span
class="n">manager</span><span class="o">.</span> <span class="n">Manages</span>
<span class="n">the</span> <span class="n">configuration</span> <span
class="n">of</span> <span class="n">an</span> <span
class="n">application</span><span class="o">.</span> <span class="n">Has</span>
<span class="n">features</span>
- <span class="o">*</span> <span class="n">to</span> <span
class="nb">import</span> <span class="ow">and</span> <span
class="n">export</span> <span class="n">whole</span> <span
class="n">configurations</span> <span class="ow">and</span> <span
class="n">notifies</span> <span class="n">components</span> <span
class="n">that</span> <span class="n">need</span> <span class="n">to</span>
- <span class="o">*</span> <span class="n">receive</span> <span
class="n">settings</span><span class="o">.</span>
- <span class="o">*/</span>
+<div class="codehilite"><pre><span class="cm">/**</span>
+<span class="cm"> * Configuration manager. Manages the configuration of an
application. Has features</span>
+<span class="cm"> * to import and export whole configurations and notifies
components that need to</span>
+<span class="cm"> * receive settings.</span>
+<span class="cm"> */</span>
</pre></div>
@@ -239,22 +302,22 @@
</table>
<h5 id="annotations">Annotations</h5>
<p>Annotations for classes and methods should be done on the line directly
above the class or method. They should be indented to the same level. An
example:</p>
-<div class="codehilite"><pre><span class="nv">@Manageable</span><span
class="p">(</span><span class="n">description</span> <span class="o">=</span>
<span class="s">"Starts the system."</span><span class="p">)</span>
-<span class="n">public</span> <span class="n">void</span> <span
class="n">start</span><span class="p">()</span> <span class="p">{</span>
- <span class="sr">//</span> <span class="o">...</span>
-<span class="p">}</span>
+<div class="codehilite"><pre><span class="nd">@Manageable</span><span
class="o">(</span><span class="n">description</span> <span class="o">=</span>
<span class="s">"Starts the system."</span><span class="o">)</span>
+<span class="kd">public</span> <span class="kt">void</span> <span
class="nf">start</span><span class="o">()</span> <span class="o">{</span>
+ <span class="c1">// ...</span>
+<span class="o">}</span>
</pre></div>
<p>Annotations for parameters can be inlined like this:</p>
-<div class="codehilite"><pre><span class="n">public</span> <span
class="n">void</span> <span class="n">setValue</span><span
class="p">(</span><span class="nv">@Validation</span><span
class="p">(</span><span class="s">"x > 0 && x <
10"</span><span class="p">,</span> <span class="s">"Should be between
0 and 10."</span><span class="p">)</span> <span class="nb">int</span>
<span class="n">x</span><span class="p">)</span> <span class="p">{</span>
- <span class="sr">//</span> <span class="o">...</span>
-<span class="p">}</span>
+<div class="codehilite"><pre><span class="kd">public</span> <span
class="kt">void</span> <span class="nf">setValue</span><span
class="o">(</span><span class="nd">@Validation</span><span
class="o">(</span><span class="s">"x > 0 && x <
10"</span><span class="o">,</span> <span class="s">"Should be between
0 and 10."</span><span class="o">)</span> <span class="kt">int</span>
<span class="n">x</span><span class="o">)</span> <span class="o">{</span>
+ <span class="c1">// ...</span>
+<span class="o">}</span>
</pre></div>
<h3 id="indentation">Indentation</h3>
-<p>Four spaces should be used as unit of indentation. Use spaces or let your
editor convert tabs to spaces as some editors might show the tabs different
than they were intended! Tabs must be set exactly every 4 spaces.</p>
+<p>Four spaces should be used as unit of indentation. Use spaces or let your
editor convert tabs to spaces as some editors might show the tabs different
than they were intended! Tabs <em>must</em> be set <em>exactly</em> every 4
spaces.</p>
<h4 id="line-length">Line length</h4>
<p>There is no explicit limit for the length of a line. Make sure that the
flow of the code is clear and that, when printing the file, it is well formed
when using a reasonable font.</p>
<h4 id="wrapping-lines">Wrapping lines</h4>
@@ -275,39 +338,39 @@
<li>JavaDoc comments.</li>
</ol>
<h5 id="single-line-comments">Single line comments</h5>
-<p>The compiler ignores everything from // to the end of the line. Use this
style when adding a description or some kind of explanation on the same line of
code or the line above.</p>
-<div class="codehilite"><pre><span class="nb">int</span> <span
class="n">a</span><span class="p">;</span> <span class="sr">//</span> <span
class="n">acceleration</span> <span class="n">of</span> <span
class="n">the</span> <span class="n">car</span>
+<p>The compiler ignores everything from <code>//</code> to the end of the
line. Use this style when adding a description or some kind of explanation on
the same line of code or the line above.</p>
+<div class="codehilite"><pre><span class="kt">int</span> <span
class="n">a</span><span class="o">;</span> <span class="c1">// acceleration of
the car</span>
-<span class="sr">//</span> <span class="n">all</span> <span
class="n">names</span> <span class="n">that</span> <span
class="n">should</span> <span class="n">be</span> <span
class="n">searched</span>
-<span class="n">String</span><span class="o">[]</span> <span
class="n">names</span><span class="p">;</span>
+<span class="c1">// all names that should be searched</span>
+<span class="n">String</span><span class="o">[]</span> <span
class="n">names</span><span class="o">;</span>
</pre></div>
<h5 id="block-comments">Block comments</h5>
-<p>The compiler ignores everything from /<em> to </em>/. Use this style for
internal comments and copyright headers.</p>
-<div class="codehilite"><pre><span class="o">/*</span>
- <span class="o">*</span> <span class="n">This</span> <span
class="n">code</span> <span class="n">is</span> <span
class="n">Copyright</span> <span class="p">(</span><span
class="n">c</span><span class="p">)</span> <span class="mi">2012</span> <span
class="n">Apache</span> <span class="n">Software</span> <span
class="n">Foundation</span><span class="o">.</span> <span class="n">All</span>
<span class="n">rights</span> <span class="n">reserved</span><span
class="o">.</span>
- <span class="o">*</span> <span class="n">You</span> <span
class="n">are</span> <span class="ow">not</span> <span class="n">allowed</span>
<span class="n">to</span> <span class="n">remember</span> <span
class="ow">or</span> <span class="n">reproduce</span> <span
class="n">anything</span> <span class="n">you</span> <span
class="nb">read</span> <span class="n">below</span><span class="o">.</span>
- <span class="o">*/</span>
+<p>The compiler ignores everything from <code>/*</code> to <code>*/</code>.
Use this style for internal comments and copyright headers.</p>
+<div class="codehilite"><pre><span class="cm">/*</span>
+<span class="cm"> * This code is Copyright (c) 2012 Apache Software
Foundation. All rights reserved.</span>
+<span class="cm"> * You are not allowed to remember or reproduce anything you
read below.</span>
+<span class="cm"> */</span>
</pre></div>
<h5 id="javadoc-comments">JavaDoc comments</h5>
-<p>This indicates a documentation comment (doc comment, for short). The
compiler ignores this kind of comment, just like it ignores comments that use
/<em> and </em>/. The JavaDoc tool uses doc comments when preparing
automatically generated documentation (See: JavaDoc keywords and HTML tags).
Note that JavaDoc only uses this documentation when it occurs at an expected
position in the file like the class definition or a member declaration. </p>
+<p>This indicates a documentation comment (doc comment, for short). The
compiler ignores this kind of comment, just like it ignores comments that use
<code>/*</code> and <code>*/</code>. The JavaDoc tool uses doc comments when
preparing automatically generated documentation (See: JavaDoc keywords and HTML
tags). Note that JavaDoc only uses this documentation when it occurs at an
expected position in the file like the class definition or a member
declaration. </p>
<p>These comments are used to provide English descriptions of the classes,
interfaces, enums, annotations, methods and the description of data structures
and algorithms. These comments should be used at the beginning of each class
and before each method. The official JavaDoc guidelines (see references at the
end of this document) should be followed, as they provide a good and clear
writing style.</p>
<p>A method block comment looks as follows:</p>
-<div class="codehilite"><pre><span class="o">/**</span>
- <span class="o">*</span> <span class="n">Position</span> <span
class="n">the</span> <span class="n">splitter</span> <span
class="n">location</span> <span class="n">at</span> <span class="n">a</span>
<span class="n">specified</span> <span class="n">position</span><span
class="o">.</span>
- <span class="o">*</span> <span class="n">This</span> <span
class="n">method</span> <span class="n">can</span> <span class="k">for</span>
<span class="n">instance</span> <span class="n">be</span> <span
class="n">used</span> <span class="n">when</span> <span class="n">the</span>
<span class="k">last</span> <span class="n">position</span>
- <span class="o">*</span> <span class="n">is</span> <span
class="n">stored</span> <span class="n">as</span> <span class="n">a</span>
<span class="n">preference</span> <span class="n">setting</span> <span
class="k">for</span> <span class="n">the</span> <span
class="n">user</span><span class="o">.</span>
- <span class="o">*</span>
- <span class="o">*</span> <span class="nv">@param</span> <span
class="n">position</span> <span class="n">New</span> <span
class="n">position</span> <span class="n">of</span> <span
class="n">divider</span><span class="p">,</span> <span
class="nb">defined</span> <span class="n">in</span> <span
class="n">pixels</span>
- <span class="o">*</span> <span class="n">from</span> <span
class="n">the</span> <span class="n">left</span> <span class="n">of</span>
<span class="n">the</span> <span class="n">containing</span> <span
class="n">window</span><span class="o">.</span>
- <span class="o">*</span> <span class="nv">@exception</span> <span
class="n">org</span><span class="o">.</span><span class="n">apache</span><span
class="o">.</span><span class="n">ace</span><span class="o">.</span><span
class="n">units</span><span class="o">.</span><span class="n">si</span><span
class="o">.</span><span class="n">exceptions</span><span
class="o">.</span><span class="n">PositionException</span> <span
class="n">Whenever</span>
- <span class="o">*</span> <span class="n">an</span> <span
class="n">invalid</span> <span class="n">position</span> <span
class="n">is</span> <span class="n">passed</span><span class="o">.</span>
- <span class="o">*</span> <span class="nv">@see</span> <span
class="n">com</span><span class="o">.</span><span class="n">sun</span><span
class="o">.</span><span class="n">java</span><span class="o">.</span><span
class="n">swing</span><span class="o">.</span><span class="n">JSplitPane</span>
- <span class="o">*/</span>
-<span class="n">public</span> <span class="n">void</span> <span
class="n">setSplitterLocation</span><span class="p">(</span><span
class="nb">int</span> <span class="n">position</span><span class="p">)</span>
<span class="n">throws</span> <span class="n">PositionException</span> <span
class="p">{</span>
+<div class="codehilite"><pre><span class="cm">/**</span>
+<span class="cm"> * Position the splitter location at a specified
position.</span>
+<span class="cm"> * This method can for instance be used when the last
position</span>
+<span class="cm"> * is stored as a preference setting for the user.</span>
+<span class="cm"> *</span>
+<span class="cm"> * @param position New position of divider, defined in
pixels</span>
+<span class="cm"> * from the left of the containing window.</span>
+<span class="cm"> * @exception
org.apache.ace.units.si.exceptions.PositionException Whenever</span>
+<span class="cm"> * an invalid position is passed.</span>
+<span class="cm"> * @see com.sun.java.swing.JSplitPane</span>
+<span class="cm"> */</span>
+<span class="kd">public</span> <span class="kt">void</span> <span
class="nf">setSplitterLocation</span><span class="o">(</span><span
class="kt">int</span> <span class="n">position</span><span class="o">)</span>
<span class="kd">throws</span> <span class="n">PositionException</span> <span
class="o">{</span>
</pre></div>
@@ -327,11 +390,11 @@
</tr>
<tr>
<td><code><br></code></td>
-<td>Break, a carriage return. For separation of two paragraphs, usage of <p>
is preferred.</td>
+<td>Break, a carriage return. For separation of two paragraphs, usage of
<code><p></code> is preferred.</td>
</tr>
<tr>
<td><code><ul><li></li></ul></code></td>
-<td>Unordered list of items. Each item should start with a <li> tag. Most
browsers format this as a bullet list.</td>
+<td>Unordered list of items. Each item should start with a
<code><li></code> tag. Most browsers format this as a bullet list.</td>
</tr>
<tr>
<td><code><code></code></code></td>
@@ -339,18 +402,18 @@
</tr>
</tbody>
</table>
-<p>There is no need to embed the parameter name in the @param tag in
<code><code></code> tags; this is done by JavaDoc automatically. The same
holds for the exception name in the @exception or @throws tag. In the
clarifying text however, use the <code><code></code> tags when refering
to parameter names etc. The example below shows the <code><code></code>
tag being used for the array parameter in the text, but not in its
definition.</p>
+<p>There is no need to embed the parameter name in the <code>@param</code> tag
in <code><code></code> tags; this is done by JavaDoc automatically. The
same holds for the exception name in the <code>@exception</code> or
<code>@throws</code> tag. In the clarifying text however, use the
<code><code></code> tags when refering to parameter names etc. The
example below shows the <code><code></code> tag being used for the array
parameter in the text, but not in its definition.</p>
<p>Example:</p>
-<div class="codehilite"><pre>/**
- * Prints a range from an object array. The range
- * is specified by the first element to print, and
- * ranges to the last element of the array.
- *
- * @param list contains the objects to print
- * @param first index of first element in
- * the <span class="nt"><code></span>list<span
class="nt"></code></span> to print
- */
-public void printRange(List<span class="nt"><Printable></span> list, int
first) {
+<div class="codehilite"><pre><span class="cm">/**</span>
+<span class="cm"> * Prints a range from an object array. The range</span>
+<span class="cm"> * is specified by the first element to print, and</span>
+<span class="cm"> * ranges to the last element of the array.</span>
+<span class="cm"> *</span>
+<span class="cm"> * @param list contains the objects to print</span>
+<span class="cm"> * @param first index of first element in </span>
+<span class="cm"> * the <code>list</code> to print</span>
+<span class="cm"> */</span>
+<span class="kd">public</span> <span class="kt">void</span> <span
class="nf">printRange</span><span class="o">(</span><span
class="n">List</span><span class="o"><</span><span
class="n">Printable</span><span class="o">></span> <span
class="n">list</span><span class="o">,</span> <span class="kt">int</span> <span
class="n">first</span><span class="o">)</span> <span class="o">{</span>
</pre></div>
@@ -358,29 +421,29 @@ public void printRange(List<span class="
<h3 id="declarations">Declarations</h3>
<p>When declaring a variable or method make the accessibility as restrictive
as possible. When using multiple keywords use the following ordering of
keywords:</p>
<ol>
-<li><em>accessibility</em> - Start with the accessibility as it makes clear if
the method or variable is reachable at all.</li>
-<li><em>static</em> (if applicable)</li>
-<li><em>final</em> (if applicable)</li>
+<li><em>accessibility</em> - Start with the accessibility as it makes clear if
the method or variable is reachable at all;</li>
+<li><em>static</em> (if applicable);</li>
+<li><em>final</em> (if applicable);</li>
<li><em>return type</em> (methods only) or type (for variables) - For
readability, the type is as close to the name as possible.</li>
</ol>
<p>This order is also compatible with the order that is used in Java for the
main() method. This results in following sequence:</p>
-<div class="codehilite"><pre><span class="sr">//</span> <span
class="n">A</span> <span class="n">familiar</span> <span class="n">one:</span>
-<span class="n">public</span> <span class="n">static</span> <span
class="n">void</span> <span class="n">main</span><span class="p">(</span><span
class="n">String</span><span class="o">[]</span> <span
class="n">args</span><span class="p">)</span> <span class="p">{}</span>
-<span class="n">private</span> <span class="n">static</span> <span
class="n">String</span> <span class="n">m_lastCreated</span> <span
class="o">=</span> <span class="n">null</span><span class="p">;</span>
-<span class="n">private</span> <span class="n">static</span> <span
class="n">final</span> <span class="nb">int</span> <span class="n">RED</span>
<span class="o">=</span> <span class="mi">4711</span><span class="p">;</span>
+<div class="codehilite"><pre><span class="c1">// A familiar one:</span>
+<span class="kd">public</span> <span class="kd">static</span> <span
class="kt">void</span> <span class="nf">main</span><span
class="o">(</span><span class="n">String</span><span class="o">[]</span> <span
class="n">args</span><span class="o">)</span> <span class="o">{}</span>
+<span class="kd">private</span> <span class="kd">static</span> <span
class="n">String</span> <span class="n">m_lastCreated</span> <span
class="o">=</span> <span class="kc">null</span><span class="o">;</span>
+<span class="kd">private</span> <span class="kd">static</span> <span
class="kd">final</span> <span class="kt">int</span> <span class="n">RED</span>
<span class="o">=</span> <span class="mi">4711</span><span class="o">;</span>
</pre></div>
<h4 id="number-per-line">Number per line</h4>
<p>One declaration per line is recommended since it encourages commenting and
it does not lead to confusing code. It also is more clear about the explicit
initialization of variables as discussed in Initialization.</p>
<p>Example:</p>
-<div class="codehilite"><pre><span class="nb">int</span> <span
class="n">level</span> <span class="o">=</span> <span class="mi">0</span><span
class="p">;</span> <span class="sr">//</span> <span class="n">level</span>
<span class="n">where</span> <span class="n">user</span> <span
class="n">enters</span> <span class="n">the</span> <span
class="nb">system</span>
-<span class="nb">int</span> <span class="n">horizontalSize</span> <span
class="o">=</span> <span class="mi">0</span><span class="p">;</span> <span
class="sr">//</span> <span class="n">horizontal</span> <span
class="n">size</span> <span class="n">of</span> <span class="n">current</span>
<span class="n">level</span> <span class="n">layer</span>
+<div class="codehilite"><pre><span class="kt">int</span> <span
class="n">level</span> <span class="o">=</span> <span class="mi">0</span><span
class="o">;</span> <span class="c1">// level where user enters the system</span>
+<span class="kt">int</span> <span class="n">horizontalSize</span> <span
class="o">=</span> <span class="mi">0</span><span class="o">;</span> <span
class="c1">// horizontal size of current level layer</span>
</pre></div>
<p>is preferred over:</p>
-<div class="codehilite"><pre><span class="nb">int</span> <span
class="n">level</span><span class="p">,</span> <span
class="n">horizontalSize</span><span class="p">;</span> <span
class="sr">//</span> <span class="n">level</span> <span class="ow">and</span>
<span class="n">size</span> <span class="n">of</span> <span
class="n">current</span> <span class="n">level</span> <span
class="n">layer</span>
+<div class="codehilite"><pre><span class="kt">int</span> <span
class="n">level</span><span class="o">,</span> <span
class="n">horizontalSize</span><span class="o">;</span> <span class="c1">//
level and size of current level layer</span>
</pre></div>
@@ -393,20 +456,20 @@ public void printRange(List<span class="
<p>When coding Java classes and interfaces, the following formatting rules
should be followed:</p>
<ul>
<li>no space between a method and its parameter list;</li>
-<li><code>\{</code> appears at the end of the same line as the
declaration;</li>
-<li><code>}</code> starts a line by itself indented to match its corresponding
opening statement, except when it is a null statement, in which the case the
<code>}</code> should appear immediately after the <code>\{</code>.</li>
+<li><code>{</code> appears at the end of the same line as the declaration;</li>
+<li><code>}</code> starts a line by itself indented to match its corresponding
opening statement, except when it is a null statement, in which the case the
<code>}</code> should appear immediately after the <code>{</code>.</li>
</ul>
<p>Example:</p>
-<div class="codehilite"><pre><span class="n">public</span> <span
class="n">class</span> <span class="n">DefaultStrategy</span> <span
class="n">extends</span> <span class="n">Strategy</span> <span
class="p">{</span>
- <span class="n">private</span> <span class="nb">int</span> <span
class="n">m_attempts</span> <span class="o">=</span> <span
class="mi">0</span><span class="p">;</span>
+<div class="codehilite"><pre><span class="kd">public</span> <span
class="kd">class</span> <span class="nc">DefaultStrategy</span> <span
class="kd">extends</span> <span class="n">Strategy</span> <span
class="o">{</span>
+ <span class="kd">private</span> <span class="kt">int</span> <span
class="n">m_attempts</span> <span class="o">=</span> <span
class="mi">0</span><span class="o">;</span>
- <span class="n">public</span> <span class="n">DefaultStrategy</span><span
class="p">(</span><span class="nb">int</span> <span
class="n">attempts</span><span class="p">)</span> <span class="p">{</span>
- <span class="n">super</span><span class="p">();</span>
- <span class="n">m_attempts</span> <span class="o">=</span> <span
class="n">attempts</span><span class="p">;</span>
- <span class="p">}</span>
+ <span class="kd">public</span> <span
class="nf">DefaultStrategy</span><span class="o">(</span><span
class="kt">int</span> <span class="n">attempts</span><span class="o">)</span>
<span class="o">{</span>
+ <span class="kd">super</span><span class="o">();</span>
+ <span class="n">m_attempts</span> <span class="o">=</span> <span
class="n">attempts</span><span class="o">;</span>
+ <span class="o">}</span>
- <span class="n">void</span> <span class="n">execute</span><span
class="p">()</span> <span class="p">{}</span>
-<span class="p">}</span>
+ <span class="kt">void</span> <span class="nf">execute</span><span
class="o">()</span> <span class="o">{}</span>
+<span class="o">}</span>
</pre></div>
@@ -416,34 +479,36 @@ public void printRange(List<span class="
<h4 id="compound-statements">Compound statements</h4>
<p>Compound statements are statements that contain lists of statements
enclosed in braces ("{...}"):</p>
<ul>
-<li>The enclosed statements should be indented one more level than the
compound statement.</li>
-<li>The opening brace should be at the end of the line that begins the
compound statement; the closing brace should begin a line and be indented to
the beginning of the compound statement. </li>
-<li>Braces are used around all statements, even single statements, when they
are part of a control structure, such as a if-else or for statement. This makes
it easier to add statements without accidentally introducing bugs due to
forgetting to add braces. </li>
+<li>The enclosed statements should be indented one more level than the
compound statement;</li>
+<li>The opening brace should be at the end of the line that begins the
compound statement; the closing brace should begin a line and be indented to
the beginning of the compound statement;</li>
+<li>Braces are used around all statements, even single statements, when they
are part of a control structure, such as a if-else or for statement. This makes
it easier to add statements without accidentally introducing bugs due to
forgetting to add braces.</li>
</ul>
<h4 id="if-if-else-if-else-if-else-statements">if, if-else, if else-if else
statements</h4>
<p>There are a lot of nested possibilities for if-else constructions. All
these variations can be programmed in very cryptic ways that easily and often
will lead to buggy code. By being more explicit in the used coding style a lot
of confusion can be taken away.</p>
-<p>{note}When using only one statement in a compound block brackets are
optional. It is good practice, and therefore required, to always use brackets
because mistakes can be made easily when adding a second statement and brackets
are forgotten.{note}</p>
+<blockquote>
+<p>When using only one statement in a compound block brackets are optional. It
is good practice, and therefore required, to always use brackets because
mistakes can be made easily when adding a second statement and brackets are
forgotten.</p>
+</blockquote>
<p>The following example illustrates the correct use of brackets in a few
different if-then-else constructions:</p>
-<div class="codehilite"><pre><span class="k">if</span> <span
class="p">(</span><span class="n">condition</span><span class="p">)</span>
<span class="p">{</span>
- <span class="n">statement1</span><span class="p">;</span>
- <span class="n">statement2</span><span class="p">;</span>
-<span class="p">}</span>
-<span class="k">else</span> <span class="p">{</span>
- <span class="n">statement3</span><span class="p">;</span>
-<span class="p">}</span>
-
-<span class="k">if</span> <span class="p">(</span><span
class="n">condition</span><span class="p">)</span> <span class="p">{</span>
- <span class="n">statement1</span><span class="p">;</span>
- <span class="n">statement2</span><span class="p">;</span>
-<span class="p">}</span>
-<span class="k">else</span> <span class="k">if</span> <span
class="p">(</span><span class="n">condition1</span><span class="p">)</span>
<span class="p">{</span>
- <span class="n">statement3</span><span class="p">;</span>
- <span class="n">statement4</span><span class="p">;</span>
-<span class="p">}</span>
-<span class="k">else</span> <span class="p">{</span>
- <span class="n">statement5</span><span class="p">;</span>
- <span class="n">statement6</span><span class="p">;</span>
-<span class="p">}</span>
+<div class="codehilite"><pre><span class="k">if</span> <span
class="o">(</span><span class="n">condition</span><span class="o">)</span>
<span class="o">{</span>
+ <span class="n">statement1</span><span class="o">;</span>
+ <span class="n">statement2</span><span class="o">;</span>
+<span class="o">}</span>
+<span class="k">else</span> <span class="o">{</span>
+ <span class="n">statement3</span><span class="o">;</span>
+<span class="o">}</span>
+
+<span class="k">if</span> <span class="o">(</span><span
class="n">condition</span><span class="o">)</span> <span class="o">{</span>
+ <span class="n">statement1</span><span class="o">;</span>
+ <span class="n">statement2</span><span class="o">;</span>
+<span class="o">}</span>
+<span class="k">else</span> <span class="nf">if</span> <span
class="o">(</span><span class="n">condition1</span><span class="o">)</span>
<span class="o">{</span>
+ <span class="n">statement3</span><span class="o">;</span>
+ <span class="n">statement4</span><span class="o">;</span>
+<span class="o">}</span>
+<span class="k">else</span> <span class="o">{</span>
+ <span class="n">statement5</span><span class="o">;</span>
+ <span class="n">statement6</span><span class="o">;</span>
+<span class="o">}</span>
</pre></div>
@@ -451,45 +516,45 @@ public void printRange(List<span class="
<h4 id="switch">switch</h4>
<p>When using a switch statement use following guidelines:</p>
<ul>
-<li>Consider including a default case, unless it would do nothing. The break
in the default case is redundant, but it prevents a fall-through error if later
another case is added.</li>
+<li>Consider including a default case, unless it would do nothing. The break
in the default case is redundant, but it prevents a fall-through error if later
another case is added;</li>
<li>The so-called fall-through construction should be avoided. Only when there
are good reasons to use it, make sure that it is very clear that a fall-through
is used (comment it).</li>
</ul>
<p>The next example shows the sample code that uses the guidelines for a
switch statement:</p>
-<div class="codehilite"><pre><span class="n">switch</span> <span
class="p">(</span><span class="n">condition</span><span class="p">)</span>
<span class="p">{</span>
- <span class="k">case</span> <span class="n">A:</span>
- <span class="n">statements</span><span class="p">;</span>
- <span class="sr">//</span> <span class="n">falls</span> <span
class="n">through</span> <span class="n">here</span><span class="p">,</span>
<span class="n">because</span><span class="o">...</span>
- <span class="k">case</span> <span class="n">B:</span>
- <span class="n">statements</span><span class="p">;</span>
- <span class="n">break</span><span class="p">;</span>
- <span class="n">default:</span>
- <span class="n">statements</span><span class="p">;</span>
- <span class="n">break</span><span class="p">;</span>
-<span class="p">}</span>
+<div class="codehilite"><pre><span class="k">switch</span> <span
class="o">(</span><span class="n">condition</span><span class="o">)</span>
<span class="o">{</span>
+ <span class="k">case</span> <span class="nl">A:</span>
+ <span class="n">statements</span><span class="o">;</span>
+ <span class="c1">// falls through here, because...</span>
+ <span class="k">case</span> <span class="nl">B:</span>
+ <span class="n">statements</span><span class="o">;</span>
+ <span class="k">break</span><span class="o">;</span>
+ <span class="k">default</span><span class="o">:</span>
+ <span class="n">statements</span><span class="o">;</span>
+ <span class="k">break</span><span class="o">;</span>
+<span class="o">}</span>
</pre></div>
<h4 id="try-catch">try - catch</h4>
<p>A try - catch statement should have the following format:</p>
-<div class="codehilite"><pre><span class="n">try</span> <span
class="p">{</span>
- <span class="n">statements</span><span class="p">;</span>
-<span class="p">}</span>
-<span class="n">catch</span> <span class="p">(</span><span
class="n">ExceptionClass</span> <span class="n">e</span><span
class="p">)</span> <span class="p">{</span>
- <span class="n">statements</span><span class="p">;</span>
-<span class="p">}</span>
+<div class="codehilite"><pre><span class="k">try</span> <span
class="o">{</span>
+ <span class="n">statements</span><span class="o">;</span>
+<span class="o">}</span>
+<span class="k">catch</span> <span class="o">(</span><span
class="n">ExceptionClass</span> <span class="n">e</span><span
class="o">)</span> <span class="o">{</span>
+ <span class="n">statements</span><span class="o">;</span>
+<span class="o">}</span>
</pre></div>
<p>When using finally to add code that always will be executed this will look
like:</p>
-<div class="codehilite"><pre><span class="n">try</span> <span
class="p">{</span>
- <span class="n">statements</span><span class="p">;</span>
-<span class="p">}</span>
-<span class="n">catch</span> <span class="p">(</span><span
class="n">ExceptionClass</span> <span class="n">e</span><span
class="p">)</span> <span class="p">{</span>
- <span class="n">statements</span><span class="p">;</span>
-<span class="p">}</span>
-<span class="n">finally</span> <span class="p">{</span>
- <span class="n">statements</span><span class="p">;</span>
-<span class="p">}</span>
+<div class="codehilite"><pre><span class="k">try</span> <span
class="o">{</span>
+ <span class="n">statements</span><span class="o">;</span>
+<span class="o">}</span>
+<span class="k">catch</span> <span class="o">(</span><span
class="n">ExceptionClass</span> <span class="n">e</span><span
class="o">)</span> <span class="o">{</span>
+ <span class="n">statements</span><span class="o">;</span>
+<span class="o">}</span>
+<span class="k">finally</span> <span class="o">{</span>
+ <span class="n">statements</span><span class="o">;</span>
+<span class="o">}</span>
</pre></div>
@@ -497,22 +562,22 @@ public void printRange(List<span class="
<h4 id="for-loops">for loops</h4>
<p>New style for loops are generally preferred over old style ones, unless you
explicitly need the index, or you have to make the code run on pre-Java 5
virtual machines.</p>
<p>Old style, a good example that needs the index anyway:</p>
-<div class="codehilite"><pre><span class="sr">//</span> <span
class="n">lookup</span> <span class="n">a</span> <span class="n">value</span>
<span class="n">in</span> <span class="n">a</span> <span
class="n">list</span><span class="p">,</span> <span class="k">return</span>
<span class="n">the</span> <span class="nb">index</span>
-<span class="n">List</span><span class="sr"><Element></span> <span
class="n">list</span><span class="p">;</span>
-<span class="k">for</span> <span class="p">(</span><span class="nb">int</span>
<span class="n">i</span> <span class="o">=</span> <span
class="mi">0</span><span class="p">;</span> <span class="n">i</span> <span
class="o"><</span> <span class="n">list</span><span class="o">.</span><span
class="n">size</span><span class="p">();</span> <span class="n">i</span><span
class="o">++</span><span class="p">)</span> <span class="p">{</span>
- <span class="k">if</span> <span class="p">(</span><span
class="n">value</span><span class="o">.</span><span
class="n">equals</span><span class="p">(</span><span class="n">list</span><span
class="o">.</span><span class="n">get</span><span class="p">(</span><span
class="n">i</span><span class="p">))</span> <span class="p">{</span>
- <span class="k">return</span> <span class="nb">index</span><span
class="p">;</span>
- <span class="p">}</span>
-<span class="p">}</span>
+<div class="codehilite"><pre><span class="c1">// lookup a value in a list,
return the index</span>
+<span class="n">List</span><span class="o"><</span><span
class="n">Element</span><span class="o">></span> <span
class="n">list</span><span class="o">;</span>
+<span class="k">for</span> <span class="o">(</span><span class="kt">int</span>
<span class="n">i</span> <span class="o">=</span> <span
class="mi">0</span><span class="o">;</span> <span class="n">i</span> <span
class="o"><</span> <span class="n">list</span><span class="o">.</span><span
class="na">size</span><span class="o">();</span> <span class="n">i</span><span
class="o">++)</span> <span class="o">{</span>
+ <span class="k">if</span> <span class="o">(</span><span
class="n">value</span><span class="o">.</span><span
class="na">equals</span><span class="o">(</span><span
class="n">list</span><span class="o">.</span><span class="na">get</span><span
class="o">(</span><span class="n">i</span><span class="o">))</span> <span
class="o">{</span>
+ <span class="k">return</span> <span class="n">index</span><span
class="o">;</span>
+ <span class="o">}</span>
+<span class="o">}</span>
</pre></div>
<p>New style, a good example that iterates over a list without any need for an
index or type casts:</p>
-<div class="codehilite"><pre><span class="sr">//</span> <span
class="n">iterate</span> <span class="n">over</span> <span class="n">a</span>
<span class="n">list</span><span class="p">,</span> <span
class="n">printing</span> <span class="n">all</span> <span
class="nb">values</span>
-<span class="n">List</span><span class="sr"><Element></span> <span
class="n">list</span><span class="p">;</span>
-<span class="k">for</span> <span class="p">(</span><span
class="n">Element</span> <span class="n">e</span> <span class="p">:</span>
<span class="n">list</span><span class="p">)</span> <span class="p">{</span>
- <span class="n">System</span><span class="o">.</span><span
class="n">out</span><span class="o">.</span><span class="n">println</span><span
class="p">(</span><span class="s">" - "</span> <span
class="o">+</span> <span class="n">e</span><span class="p">);</span>
-<span class="p">}</span>
+<div class="codehilite"><pre><span class="c1">// iterate over a list, printing
all values</span>
+<span class="n">List</span><span class="o"><</span><span
class="n">Element</span><span class="o">></span> <span
class="n">list</span><span class="o">;</span>
+<span class="k">for</span> <span class="o">(</span><span
class="n">Element</span> <span class="n">e</span> <span class="o">:</span>
<span class="n">list</span><span class="o">)</span> <span class="o">{</span>
+ <span class="n">System</span><span class="o">.</span><span
class="na">out</span><span class="o">.</span><span
class="na">println</span><span class="o">(</span><span class="s">" -
"</span> <span class="o">+</span> <span class="n">e</span><span
class="o">);</span>
+<span class="o">}</span>
</pre></div>
@@ -529,28 +594,45 @@ public void printRange(List<span class="
<p>Blank spaces should be used in the following circumstances:</p>
<ul>
<li>
-<p>A keyword followed by a parenthesis should be separated by a space.</p>
-<p>while (index > 5) {
- // ...
-}</p>
-<p>Note that blanks should not be used between a method call and its opening
parenthesis. This helps to distinguish keywords from function calls.
-- Blanks should appear after commas in argument lists.
-- All binary and ternary operators except "." should be separated from their
operands by spaces. Blanks should never separate unary operators such as unary
minus, increment("++") and decrement("--") from their operands.</p>
-<p>a += c + d;
-a = (a + b) / (c * d);
-a = (b > c) ? b : c;
-xCoord--;</p>
+<p>A keyword followed by a parenthesis should be separated by a space:</p>
+<div class="codehilite"><pre><span class="k">while</span> <span
class="o">(</span><span class="n">index</span> <span class="o">></span>
<span class="mi">5</span><span class="o">)</span> <span class="o">{</span>
+ <span class="c1">// ...</span>
+<span class="o">}</span>
+</pre></div>
+
+
+<p>Note that blanks should not be used between a method call and its opening
parenthesis. This helps to distinguish keywords from function calls;</p>
+</li>
+<li>
+<p>Blanks should appear after commas in argument lists;</p>
+</li>
+<li>
+<p>All binary and ternary operators except "." should be separated from their
operands by spaces. Blanks should never separate unary operators such as unary
minus, increment("++") and decrement("--") from their operands:</p>
+<div class="codehilite"><pre><span class="n">a</span> <span
class="o">+=</span> <span class="n">c</span> <span class="o">+</span> <span
class="n">d</span><span class="o">;</span>
+<span class="n">a</span> <span class="o">=</span> <span
class="o">(</span><span class="n">a</span> <span class="o">+</span> <span
class="n">b</span><span class="o">)</span> <span class="o">/</span> <span
class="o">(</span><span class="n">c</span> <span class="o">*</span> <span
class="n">d</span><span class="o">);</span>
+<span class="n">a</span> <span class="o">=</span> <span
class="o">(</span><span class="n">b</span> <span class="o">></span> <span
class="n">c</span><span class="o">)</span> <span class="o">?</span> <span
class="n">b</span> <span class="o">:</span> <span class="n">c</span><span
class="o">;</span>
+<span class="n">xCoord</span><span class="o">--;</span>
+</pre></div>
+
+
</li>
<li>
-<p>The expressions in a for statement should be separated by blanks.</p>
-<p>for (expr1; cond1; expr2) {</p>
+<p>The expressions in a for statement should be separated by blanks:</p>
+<div class="codehilite"><pre><span class="k">for</span> <span
class="o">(</span><span class="n">expr1</span><span class="o">;</span> <span
class="n">cond1</span><span class="o">;</span> <span
class="n">expr2</span><span class="o">)</span> <span class="o">{</span>
+<span class="o">}</span>
+</pre></div>
+
+
</li>
<li>
-<p>Casts should be followed by a blank.</p>
-<p>myInstance.doIt((TreeFrame) frame);</p>
+<p>Casts should be followed by a blank:</p>
+<div class="codehilite"><pre><span class="n">myInstance</span><span
class="o">.</span><span class="na">doIt</span><span class="o">((</span><span
class="n">TreeFrame</span><span class="o">)</span> <span
class="n">frame</span><span class="o">);</span>
+</pre></div>
+
+
</li>
</ul>
-<h3 id="naming-conventionsanchornamingconventions">Naming
conventions{anchor:namingconventions}</h3>
+<h3 id="namingconventions">Naming conventions</h3>
<p>Naming conventions make programs more understandable by making them easier
to read. They can also give information about the function of the
identifier.</p>
<table>
<thead>
@@ -621,21 +703,14 @@ xCoord--;</p>
<h2 id="downloads">Downloads</h2>
<p>For various coding style checkers and IDE's we have configuration files
that support this style guide. You can download them from the list below:</p>
<ul>
-<li>[Checkstyle
configuration|http://svn.apache.org/repos/asf/incubator/ace/trunk/etc/style-guide/checkstyle/]</li>
+<li><a
href="http://svn.apache.org/repos/asf/ace/trunk/etc/style-guide/checkstyle/";>Checkstyle
configuration</a></li>
</ul>
<h2 id="references">References</h2>
<ul>
-<li>Java Code Conventions - Sun Microsystems, Inc.</li>
-</ul>
-<p>http://java.sun.com/docs/codeconv/</p>
-<ul>
-<li>How to Write Doc Comments for JavaDoc - Sun Microsystems, Inc.</li>
-</ul>
-<p>http://java.sun.com/j2se/javadoc/writingdoccomments/</p>
-<ul>
-<li>JavaDoc homepage - Sun Microsystems, Inc.</li>
-</ul>
-<p>http://java.sun.com/j2se/javadoc/</p></div>
+<li>Java Code Conventions - Sun Microsystems, Inc., <a
href="http://java.sun.com/docs/codeconv/";>http://java.sun.com/docs/codeconv/</a>;</li>
+<li>How to Write Doc Comments for JavaDoc - Sun Microsystems, Inc., <a
href="http://java.sun.com/j2se/javadoc/writingdoccomments/";>http://java.sun.com/j2se/javadoc/writingdoccomments/</a>;</li>
+<li>JavaDoc homepage - Sun Microsystems, Inc., <a
href="http://java.sun.com/j2se/javadoc/";>http://java.sun.com/j2se/javadoc/</a>.</li>
+</ul></div>
<hr>
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<p>Copyright © 2012 <a href="http://www.apache.org/";>The Apache
Software Foundation</a>, Licensed under the <a
href="http://www.apache.org/licenses/LICENSE-2.0";>Apache License, Version
2.0</a>.<br/>Apache ACE, the Apache ACE logo, Apache and the Apache feather
logo are trademarks of The Apache Software Foundation. All other marks
mentioned may be trademarks or registered trademarks of their respective
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