Squashed 'third_party/allwpilib_2016/' changes from 7f61816..3ce6feb
3ce6feb Updated release number for the new release
e054bbc This adds StopMotor() to the SpeedController interface for C++ and Java. For Java, this is as simple as just adding it, as all motors already have an implementation from MotorSafety that is correctly resolved. For C++, I had to override StopMotor in the classes that descend from SafePWM and explicitly call the SafePWM version. RobotDrive now calls StopMotor on each of its SpeedControllers, instead of calling Disable or setting the motor to 0.0 as it was doing previously.
a15b9dc Merge "More updates to the Gyro test fixing potential null pointer exception"
21b7213 Added Config routine to allow enabling/disabling of limit switch and soft limits. This improves upon the ConfigLimitMode routine, which does not allow certain combinations of enable/disabled limit features. Also keeps parity with LV and Java.
1b45237 Merge "Add an additional member variable for "stopped" which indicates the CAN motor controller has been explicitly stopped, but not disabled by the user (main use case is MotorSafety tripping). When Set() is called the next time the controller will be re-enabled automatically."
1096b15 Add an additional member variable for "stopped" which indicates the CAN motor controller has been explicitly stopped, but not disabled by the user (main use case is MotorSafety tripping). When Set() is called the next time the controller will be re-enabled automatically.
7da21fa More updates to the Gyro test fixing potential null pointer exception
ede5862 Rate-limit duplicate error messages to avoid flooding console.
c22284d Merge "artf4818: Fix CAN Talon JNI references with underscores."
cac3741 Merge "Updated PDP port of Talon and disabled PDP tests for Victor and Jaguar since the Victor and Jaguar don't draw enough current for the PDP to read above 0. PDP tests for both java and cpp only test the Talon now."
097aa8c Fixed the gyro deviation over time test
1d647b3 artf4818: Fix CAN Talon JNI references with underscores.
368cfc7 Merge "Fixed the motor tests by reducing speed to within the limits of the encoders we use. Also fixed java pid tolerances since getAvgError() was broken. It is now fixed and works properly. Added tests for both java and cpp that test if pid tolerances are working using fake input output pairs."
833e459 Updated PDP port of Talon and disabled PDP tests for Victor and Jaguar since the Victor and Jaguar don't draw enough current for the PDP to read above 0. PDP tests for both java and cpp only test the Talon now.
6c096a3 Fixed the motor tests by reducing speed to within the limits of the encoders we use. Also fixed java pid tolerances since getAvgError() was broken. It is now fixed and works properly. Added tests for both java and cpp that test if pid tolerances are working using fake input output pairs.
dd7eb0f Fixed robot drive for C++ Simulation
258a622 Merge "Update version number for Release 3 Print distinctive message on robot program startup Change-Id: Ic91b81bd298ee6730503933cf0e733702e4b4405"
b1386c6 Update version number for Release 3 Print distinctive message on robot program startup Change-Id: Ic91b81bd298ee6730503933cf0e733702e4b4405
a58de40 Merge "Removed publishing of java sim jar"
792d0d3 PDP Classes should support any PDP address
35df955 Merge "Remove maven local as a possible search location"
a0ce9ee Another improvement to HAL-joy getting to ensure it works in future RIO image updates.
0f02c31 Removed publishing of java sim jar
8435ac7 DriverStation::GetJoystickName(): Make work for stick>0.
b4cf4f4 Remove maven local as a possible search location
c3000c3 Merge "Fix HALGetJoystickDescriptor()."
4dec0b4 Merge "Fixed Simulation C++ API"
abc9c27 Fixed Simulation C++ API
b8ae9ec Fix HALGetJoystickDescriptor().
a60f874 Artf4800: Fixes HALGetJoystick*** Segfault
010b584 Merge "fix sim_ds launch script"
4429e16 Merge "Added build dir specification for sim javadoc to not overwrite athena javadoc"
ec9349b Initialized the m_sensors variable to fix artf4798.
9745af8 Added build dir specification for sim javadoc to not overwrite athena javadoc
4da8702 fix sim_ds launch script
05acf79 Fix C++ PIDController SetToleranceBuffer and OnTarget locking.
94a6b05 Merge "Fix onTarget() so that it returns false until there are any values retrieved"
d06053d Fix onTarget() so that it returns false until there are any values retrieved
74927cc Correctly set smart dashboard type for AnalogGyro and ADXRS450_Gyro.
070752f Merge "Fixed sim_ds script library path"
21a8bab Merge "PIDController feed forward term can now be calculated by the end user"
56bd6da Fixed sim_ds script library path
07710f1 Merge "Fixing install script... again"
e1cb61f Use absolute path for NT persistent storage.
09c7482 Fixing install script... again
a3b8bec PIDController feed forward term can now be calculated by the end user
790adb0 artf2612: Update license in source files.
042671c Merge "Removed gz_msgs from wpilibcSim"
c111690 Ultrasonic: replace linked list with std::set.
d71a8ed Removed gz_msgs from wpilibcSim
37259f7 Merge "Replaced linked list in Notifier with std::list"
cd17e7a Merge "Renamed Gyro to AnalogGyro to match athena API"
c5c8a87 Replaced linked list in Notifier with std::list
89405d8 Renamed Gyro to AnalogGyro to match athena API
4a19490 Merge "Adds CANTalon to LiveWindow"
c4a3567 Merge "Fixing the frcsim installer script"
295648f Adds CANTalon to LiveWindow
1b964a2 Merge "Fixes CAN devices in C++ library not showing in the livewindow"
7ba5cee Merge "HAL: Use extern "C" in implementation files."
d17d242 Fixes CAN devices in C++ library not showing in the livewindow
25a771a Added linear digital filters
7349c2c Fixing the frcsim installer script
c82122c Merge "Default bufLength for PIDController in Java should be 1"
58f3f97 Merge "Adds WaitResult to Java waitForInterrupt"
bc8ed12 HAL: Use extern "C" in implementation files.
4cac89e Default bufLength for PIDController in Java should be 1
64fcdcc Keep track of FPGA time rollovers with 64-bit time.
d30b283 Merge "Change C++ Notifier to allow std::function callback."
6ee3052 Merge "Rewrite C++ Notifier to use HAL multi-notifier support."
f5d09e2 Merge "Rewrite Java Notifier and update Interrupt JNI."
d0274aa Merge "Readded styleguide accidentally removed in the reorg"
68311ad Merge "Artf4179: Allow alternate I2C addresses for ADXL345_I2C"
dee12d4 Readded styleguide accidentally removed in the reorg
fa100df Fixed some typos in the comments of MotorEncoderFixture.java, a method name in CANMotorEncoderFixture.java, and the README files
3397b5c Adds WaitResult to Java waitForInterrupt
5f0dffd Artf4177: Use read byte count for ReadString
8564f33 Artf4179: Allow alternate I2C addresses for ADXL345_I2C
e52b52d Change C++ Notifier to allow std::function callback.
40b29e7 Rewrite C++ Notifier to use HAL multi-notifier support.
d126f45 Rewrite Java Notifier and update Interrupt JNI.
557805a Merge "finishing up FRCSim installer"
911b64b finishing up FRCSim installer
e24fe6f Merge "Artf4776 Fixes First DIO PWM usage errors"
f8f9284 Merge "Artf4774 Fixes HAL getHALErrorMessage missing error"
84428d5 Merge "Prevent double free in DigitalGlitchFilter"
a00a5ff Merge "Set correct error message"
9aeee98 Prevent double free in DigitalGlitchFilter
5d2186c working on install process for FRCSim 2016
7fdb616 Merge "This commit adds documentation generation, including grabbing ntcore sources, for both Java and C++. This will need changes made in the wpilib promotion tasks to copy the generatd documentation to the correct places."
f67ebca Improved READMEs
8a7c019 Artf4776 Fixes First DIO PWM usage errors
1cd2f9a Added libnipalu to make vision programs link properly
375b92a This commit adds documentation generation, including grabbing ntcore sources, for both Java and C++. This will need changes made in the wpilib promotion tasks to copy the generatd documentation to the correct places.
8d0a990 Set correct error message
b65401f Artf4774 Fixes HAL getHALErrorMessage missing error
5f918be Condition java sim build on -PmakeSim flag
53bd180 Merge "Add SPARK and SD540 motor controllers"
66cbe69 Fixed double free of DriverStation.
431f345 Repaired simulation build on linux
611593c Add Cmake wrappers and unzip desktop ntcore builds
51a18cd Add SPARK and SD540 motor controllers
c05e883 Merge changes I55ce71c6,I803680c1
2b80029 Rewrite CANTalon JNI layer.
ef4c45b Last feature addition for CANTalon java/C++ user-facing API.
Change-Id: Ia3a124978a426991890b6f8abbe07d34d75ba38d
git-subtree-dir: third_party/allwpilib_2016
git-subtree-split: 3ce6feb8acdeca46e93a55280fb6ace3a4d5bcd6
diff --git a/styleguide/javaguide.html b/styleguide/javaguide.html
new file mode 100644
index 0000000..da34b85
--- /dev/null
+++ b/styleguide/javaguide.html
@@ -0,0 +1,806 @@
+<html lang="en">
+<head>
+ <meta http-equiv="content-type" content="text/html; charset=UTF-8" />
+ <link rel="stylesheet" type="text/css" href="javaguide.css"/>
+ <script src="https://google-code-prettify.googlecode.com/svn/loader/run_prettify.js"
+ type="text/javascript"></script>
+ <link href="http://www.google.com/favicon.ico"
+ type="image/x-icon" rel="shortcut icon" />
+ <title>WPILib Java Style</title>
+</head>
+<body>
+<h1>WPILib Java Style (Based on the
+ <a href=http://google-styleguide.googlecode.com/svn/trunk/javaguide.html>Google Java Style Guide</a>)</h1>
+ <div class="change">Last changed: June 19, 2015</div>
+<table border="0">
+<tr>
+<td>
+<dl>
+<br>
+<dt class="toc1">
+<a href="#s1-introduction">1 Introduction</a>
+</dt>
+<dd>
+<a href="#s1.1-terminology">1.1 Terminology notes</a>
+</dd>
+<dd>
+<a href="#s1.2-guide-notes">1.2 Guide notes</a>
+</dd>
+<br>
+<dt class="toc1">
+<a href="#s2-source-file-basics">2 Source file basics</a>
+</dt>
+<dd>
+<a href="#s2.1-file-name">2.1 File name</a>
+</dd>
+<dd>
+<a href="#s2.2-file-encoding">2.2 File encoding: UTF-8</a>
+</dd>
+<dd>
+<a href="#s2.3-special-characters">2.3 Special characters</a>
+</dd>
+<dd class="toc3">
+<a href="#s2.3.1-whitespace-characters">2.3.1 Whitespace characters</a>
+</dd>
+<dd class="toc3">
+<a href="#s2.3.2-special-escape-sequences">2.3.2 Special escape sequences</a>
+</dd>
+<dd class="toc3">
+<a href="#s2.3.3-non-ascii-characters">2.3.3 Non-ASCII characters</a>
+</dd>
+<br>
+<dt class="toc1">
+<a href="#s3-source-file-structure">3 Source file structure</a>
+</dt>
+<dd>
+<a href="#s3.1-copyright-statement">3.1 License or copyright information, if present</a>
+</dd>
+<dd>
+<a href="#s3.2-package-statement">3.2 Package statement</a>
+</dd>
+<dd>
+<a href="#s3.3-import-statements">3.3 Import statements</a>
+</dd>
+<dd class="toc3">
+<a href="#s3.3.1-wildcard-imports">3.3.1 No wildcard imports</a>
+</dd>
+<dd class="toc3">
+<a href="#s3.3.2-import-line-wrapping">3.3.2 No line-wrapping</a>
+</dd>
+<dd class="toc3">
+<a href="#s3.3.3-import-ordering-and-spacing">3.3.3 Ordering and spacing</a>
+</dd>
+<dd>
+<a href="#s3.4-class-declaration">3.4 Class declaration</a>
+</dd>
+<dd class="toc3">
+<a href="#s3.4.1-one-top-level-class">3.4.1 Exactly one top-level class declaration</a>
+</dd>
+<dd class="toc3">
+<a href="#s3.4.2-class-member-ordering">3.4.2 Class member ordering</a>
+</dd>
+</dl>
+</td><td>
+<dl>
+<br>
+<dt class="toc1">
+<a href="#s4-formatting">4 Formatting</a>
+</dt>
+<dd>
+<a href="#s4.1-braces">4.1 Braces</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.1.1-braces-always-used">4.1.1 Braces are used where optional</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.1.2-blocks-k-r-style">4.1.2 Nonempty blocks: K & R style</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.1.3-braces-empty-blocks">4.1.3 Empty blocks: may be concise</a>
+</dd>
+<dd>
+<a href="#s4.2-block-indentation">4.2 Block indentation: +2 spaces</a>
+</dd>
+<dd>
+<a href="#s4.3-one-statement-per-line">4.3 One statement per line</a>
+</dd>
+<dd>
+<a href="#s4.4-column-limit">4.4 Column limit: 80 or 100</a>
+</dd>
+<dd>
+<a href="#s4.5-line-wrapping">4.5 Line-wrapping</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.5.1-line-wrapping-where-to-break">4.5.1 Where to break</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.5.2-line-wrapping-indent">4.5.2 Indent continuation lines at least +4 spaces</a>
+</dd>
+<dd>
+<a href="#s4.6-whitespace">4.6 Whitespace</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.6.1-vertical-whitespace">4.6.1 Vertical Whitespace</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.6.2-horizontal-whitespace">4.6.2 Horizontal whitespace</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.6.3-horizontal-alignment">4.6.3 Horizontal alignment: never required</a>
+</dd>
+<dd>
+<a href="#s4.7-grouping-parentheses">4.7 Grouping parentheses: recommended</a>
+</dd>
+<dd>
+<a href="#s4.8-specific-constructs">4.8 Specific constructs</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.8.1-enum-classes">4.8.1 Enum classes</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.8.2-variable-declarations">4.8.2 Variable declarations</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.8.3-arrays">4.8.3 Arrays</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.8.4-switch">4.8.4 Switch statements</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.8.5-annotations">4.8.5 Annotations</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.8.6-comments">4.8.6 Comments</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.8.7-modifiers">4.8.7 Modifiers</a>
+</dd>
+<dd class="toc3">
+<a href="#s4.8.8-numeric-literals">4.8.8 Numeric Literals</a>
+</dd>
+</dl>
+</td><td>
+<dl>
+<br>
+<dt class="toc1">
+<a href="#s5-naming">5 Naming</a>
+</dt>
+<dd>
+<a href="#s5.1-identifier-names">5.1 Rules common to all identifiers</a>
+</dd>
+<dd>
+<a href="#s5.2-specific-identifier-names">5.2 Rules by identifier type</a>
+</dd>
+<dd class="toc3">
+<a href="#s5.2.1-package-names">5.2.1 Package names</a>
+</dd>
+<dd class="toc3">
+<a href="#s5.2.2-class-names">5.2.2 Class names</a>
+</dd>
+<dd class="toc3">
+<a href="#s5.2.3-method-names">5.2.3 Method names</a>
+</dd>
+<dd class="toc3">
+<a href="#s5.2.4-constant-names">5.2.4 Constant names</a>
+</dd>
+<dd class="toc3">
+<a href="#s5.2.5-non-constant-field-names">5.2.5 Non-constant field names</a>
+</dd>
+<dd class="toc3">
+<a href="#s5.2.6-parameter-names">5.2.6 Parameter names</a>
+</dd>
+<dd class="toc3">
+<a href="#s5.2.7-local-variable-names">5.2.7 Local variable names</a>
+</dd>
+<dd class="toc3">
+<a href="#s5.2.8-type-variable-names">5.2.8 Type variable names</a>
+</dd>
+<dd>
+<a href="#s5.3-camel-case">5.3 Camel case: defined</a>
+</dd>
+<br>
+<dt class="toc1">
+<a href="#s6-programming-practices">6 Programming Practices</a>
+</dt>
+<dd>
+<a href="#s6.1-override-annotation">6.1 @Override: always used</a>
+</dd>
+<dd>
+<a href="#s6.2-caught-exceptions">6.2 Caught exceptions: not ignored</a>
+</dd>
+<dd>
+<a href="#s6.3-static-members">6.3 Static members: qualified using class</a>
+</dd>
+<dd>
+<a href="#s6.4-finalizers">6.4 Finalizers: not used</a>
+</dd>
+<br>
+<dt class="toc1">
+<a href="#s7-javadoc">7 Javadoc</a>
+</dt>
+<dd>
+<a href="#s7.1-javadoc-formatting">7.1 Formatting</a>
+</dd>
+<dd class="toc3">
+<a href="#s7.1.1-javadoc-multi-line">7.1.1 General form</a>
+</dd>
+<dd class="toc3">
+<a href="#s7.1.2-javadoc-paragraphs">7.1.2 Paragraphs</a>
+</dd>
+<dd class="toc3">
+<a href="#s7.1.3-javadoc-at-clauses">7.1.3 At-clauses</a>
+</dd>
+<dd>
+<a href="#s7.2-summary-fragment">7.2 The summary fragment</a>
+</dd>
+<dd>
+<a href="#s7.3-javadoc-where-required">7.3 Where Javadoc is used</a>
+</dd>
+<dd class="toc3">
+<a href="#s7.3.1-javadoc-exception-self-explanatory">7.3.1 Exception: self-explanatory methods</a>
+</dd>
+<dd class="toc3">
+<a href="#s7.3.2-javadoc-exception-overrides">7.3.2 Exception: overrides</a>
+</dd>
+</dl>
+</td>
+</tr>
+</table>
+<div><a name="s1-introduction"/>
+ <h2>1 Introduction <a href="#s1-introduction"><img height="21" width="21" src="javaguidelink.png"/></a></h2>
+
+<p><strong>This guide is a work in progress.</strong>
+We are currently working on getting this guide updated to
+a point where it is useful for WPILib developers to use.</p>
+
+ <p>This document serves as the style guide for WPILib. It is <em>heavily</em>
+ based on the Google Java Style Guide and copies pretty much word-for-word
+ the formatting/style components of the guide while cutting a couple
+ of the programming practices. As this guide evolves, we will likely
+ introduce more suggested/mandated programming practices specific
+ to WPILib.</p>
+ <p>It is encouraged that anyone working on the Java WPILib also
+ read the corresponding C++ guide, as we generally try to develop
+ the C++ and Java components of the library in parallel and many
+ programming practices true in one language will be true in the other
+ (although this is not universally true).</p>
+</p><a name="s1.1-terminology"/>
+ <h3>1.1 Terminology notes <a href="#s1.1-terminology"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>In this document, unless otherwise clarified:</p><ol><li>The term <em>class</em> is used inclusively to mean an "ordinary" class, enum class,
+ interface or annotation type (<code class="prettyprint lang-java">@interface</code>).</li><li>The term <em>comment</em> always refers to <em>implementation</em> comments. We do not
+ use the phrase "documentation comments", instead using the common term "Javadoc."</li></ol><p>Other "terminology notes" will appear occasionally throughout the document.</p><a name="s1.2-guide-notes"/>
+ <h3>1.2 Guide notes <a href="#s1.2-guide-notes"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>Example code in this document is <strong>non-normative</strong>. That is, while the examples
+are in Google Style, they may not illustrate the <em>only</em> stylish way to represent the
+code. Optional formatting choices made in examples should not be enforced as rules.</p><a name="s2-source-file-basics"/>
+ <h2>2 Source file basics <a href="#s2-source-file-basics"><img height="21" width="21" src="javaguidelink.png"/></a></h2>
+ <a name="s2.1-file-name"/>
+ <h3>2.1 File name <a href="#s2.1-file-name"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>The source file name consists of the case-sensitive name of the top-level class it contains,
+plus the <code>.java</code> extension.</p><a name="s2.2-file-encoding"/>
+ <h3>2.2 File encoding: UTF-8 <a href="#s2.2-file-encoding"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>Source files are encoded in <strong>UTF-8</strong>.</p><a name="s2.3-special-characters"/>
+ <h3>2.3 Special characters <a href="#s2.3-special-characters"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <a name="s2.3.1-whitespace-characters"/>
+ <h4>2.3.1 Whitespace characters <a href="#s2.3.1-whitespace-characters"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Aside from the line terminator sequence, the <strong>ASCII horizontal space
+character</strong> (<strong>0x20</strong>) is the only whitespace character that appears
+anywhere in a source file. This implies that:</p><ol><li>All other whitespace characters in string and character literals are escaped.</li><li>Tab characters are <strong>not</strong> used for indentation.</li></ol><a name="s2.3.2-special-escape-sequences"/>
+ <h4>2.3.2 Special escape sequences <a href="#s2.3.2-special-escape-sequences"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>For any character that has a special escape sequence
+(<code class="prettyprint lang-java">\b</code>,
+<code class="prettyprint lang-java">\t</code>,
+<code class="prettyprint lang-java">\n</code>,
+<code class="prettyprint lang-java">\f</code>,
+<code class="prettyprint lang-java">\r</code>,
+<code class="prettyprint lang-java">\"</code>,
+<code class="prettyprint lang-java">\'</code> and
+<code class="prettyprint lang-java">\\</code>), that sequence
+is used rather than the corresponding octal
+(e.g. <code class="badcode">\012</code>) or Unicode
+(e.g. <code class="badcode">\u000a</code>) escape.</p><a name="s2.3.3-non-ascii-characters"/>
+ <h4>2.3.3 Non-ASCII characters <a href="#s2.3.3-non-ascii-characters"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>For the remaining non-ASCII characters, either the actual Unicode character
+(e.g. <code class="prettyprint lang-java">∞</code>) or the equivalent Unicode escape
+(e.g. <code class="prettyprint lang-java">\u221e</code>) is used, depending only on which
+makes the code <strong>easier to read and understand</strong>.</p><p class="tip"><strong>Tip:</strong> In the Unicode escape case, and occasionally even when actual
+Unicode characters are used, an explanatory comment can be very helpful.</p><p>Examples:</p><table><tr><th>Example</th><th>Discussion</th></tr><tr><td><code class="prettyprint lang-java">String unitAbbrev = "μs";</code></td><td>Best: perfectly clear even without a comment.</td></tr><tr><td><code class="prettyprint lang-java">String unitAbbrev = "\u03bcs"; // "μs"</code></td><td>Allowed, but there's no reason to do this.</td></tr><tr><td><code class="prettyprint lang-java">String unitAbbrev = "\u03bcs";
+ // Greek letter mu, "s"</code></td><td>Allowed, but awkward and prone to mistakes.</td></tr><tr><td><code class="badcode">String unitAbbrev = "\u03bcs";</code></td><td>Poor: the reader has no idea what this is.</td></tr><tr><td><code class="prettyprint lang-java">return '\ufeff' + content;
+ // byte order mark</code></td><td>Good: use escapes for non-printable characters, and comment if necessary.</td></tr></table><p class="tip"><strong>Tip:</strong> Never make your code less readable simply out of fear that
+some programs might not handle non-ASCII characters properly. If that should happen, those
+programs are <strong>broken</strong> and they must be <strong>fixed</strong>.</p><a name="filestructure"/><a name="s3-source-file-structure"/>
+ <h2>3 Source file structure <a href="#s3-source-file-structure"><img height="21" width="21" src="javaguidelink.png"/></a></h2>
+ <div><p>A source file consists of, <strong>in order</strong>:</p><ol><li>License or copyright information, if present</li><li>Package statement</li><li>Import statements</li><li>Exactly one top-level class</li></ol></div><p><strong>Exactly one blank line</strong> separates each section that is present.</p><a name="s3.1-copyright-statement"/>
+ <h3>3.1 License or copyright information, if present <a href="#s3.1-copyright-statement"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>If license or copyright information belongs in a file, it belongs here.</p><a name="s3.2-package-statement"/>
+ <h3>3.2 Package statement <a href="#s3.2-package-statement"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>The package statement is <strong>not line-wrapped</strong>. The column limit (Section 4.4,
+<a href="#s4.4-column-limit">Column limit: 80</a>) does not apply to package statements.</p><a name="imports"/><a name="s3.3-import-statements"/>
+ <h3>3.3 Import statements <a href="#s3.3-import-statements"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <a name="s3.3.1-wildcard-imports"/>
+ <h4>3.3.1 No wildcard imports <a href="#s3.3.1-wildcard-imports"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p><strong>Wildcard imports</strong>, static or otherwise, <strong>are not used</strong>.</p><a name="s3.3.2-import-line-wrapping"/>
+ <h4>3.3.2 No line-wrapping <a href="#s3.3.2-import-line-wrapping"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Import statements are <strong>not line-wrapped</strong>. The column limit (Section 4.4,
+<a href="#s4.4-column-limit">Column limit: 80</a>) does not apply to import
+statements.</p><a name="s3.3.3-import-ordering-and-spacing"/>
+ <h4>3.3.3 Ordering and spacing <a href="#s3.3.3-import-ordering-and-spacing"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Import statements are divided into the following groups, in this order, with each group
+separated by a single blank line:</p><ol><li>All static imports in a single group</li><li><code>com.google</code> imports
+ (only if this source file is in the <code>com.google</code> package
+ space)</li><li>Third-party imports, one group per top-level package, in ASCII sort order
+ <ul><li>for example: <code>android</code>, <code>com</code>, <code>junit</code>, <code>org</code>,
+ <code>sun</code></li></ul></li><li><code>java</code> imports</li><li><code>javax</code> imports</li></ol><p>Within a group there are no blank lines, and the imported names appear in ASCII sort
+order. (<strong>Note:</strong> this is not the same as the import <em>statements</em> being in
+ASCII sort order; the presence of semicolons warps the result.)</p><a name="s3.4-class-declaration"/>
+ <h3>3.4 Class declaration <a href="#s3.4-class-declaration"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <a name="oneclassperfile"/><a name="s3.4.1-one-top-level-class"/>
+ <h4>3.4.1 Exactly one top-level class declaration <a href="#s3.4.1-one-top-level-class"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Each top-level class resides in a source file of its own.</p><a name="s3.4.2-class-member-ordering"/>
+ <h4>3.4.2 Class member ordering <a href="#s3.4.2-class-member-ordering"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>The ordering of the members of a class can have a great effect on learnability, but there is
+no single correct recipe for how to do it. Different classes may order their members
+differently.</p><p>What is important is that each class order its members in <strong><em>some</em> logical
+order</strong>, which its maintainer could explain if asked. For example, new methods are not
+just habitually added to the end of the class, as that would yield "chronological by date
+added" ordering, which is not a logical ordering.</p><a name="overloads"/><a name="s3.4.2.1-overloads-never-split"/>
+ <h5>3.4.2.1 Overloads: never split <a href="#s3.4.2.1-overloads-never-split"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>When a class has multiple constructors, or multiple methods with the same name, these appear
+sequentially, with no intervening members.</p><a name="s4-formatting"/>
+ <h2>4 Formatting <a href="#s4-formatting"><img height="21" width="21" src="javaguidelink.png"/></a></h2>
+ <p class="terminology"><strong>Terminology Note:</strong> <em>block-like construct</em> refers to
+the body of a class, method or constructor. Note that, by Section 4.8.3.1 on
+<a href="#s4.8.3.1-array-initializers">array initializers</a>, any array initializer
+<em>may</em> optionally be treated as if it were a block-like construct.</p><a name="braces"/><a name="s4.1-braces"/>
+ <h3>4.1 Braces <a href="#s4.1-braces"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <a name="s4.1.1-braces-always-used"/>
+ <h4>4.1.1 Braces are used where optional <a href="#s4.1.1-braces-always-used"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Braces are used with
+<code class="prettyprint lang-java">if</code>,
+<code class="prettyprint lang-java">else</code>,
+<code class="prettyprint lang-java">for</code>,
+<code class="prettyprint lang-java">do</code> and
+<code class="prettyprint lang-java">while</code> statements, even when the
+body is empty or contains only a single statement.</p><a name="s4.1.2-blocks-k-r-style"/>
+ <h4>4.1.2 Nonempty blocks: K & R style <a href="#s4.1.2-blocks-k-r-style"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Braces follow the Kernighan and Ritchie style
+("<a href="http://www.codinghorror.com/blog/2012/07/new-programming-jargon.html">Egyptian brackets</a>")
+for <em>nonempty</em> blocks and block-like constructs:</p><ul><li>No line break before the opening brace.</li><li>Line break after the opening brace.</li><li>Line break before the closing brace.</li><li>Line break after the closing brace <em>if</em> that brace terminates a statement or the body
+ of a method, constructor or <em>named</em> class. For example, there is <em>no</em> line break
+ after the brace if it is followed by <code class="prettyprint lang-java">else</code> or a
+ comma.</li></ul><p>Example:</p><pre class="prettyprint lang-java">
+return new MyClass() {
+ @Override public void method() {
+ if (condition()) {
+ try {
+ something();
+ } catch (ProblemException e) {
+ recover();
+ }
+ }
+ }
+};
+</pre><p>A few exceptions for enum classes are given in Section 4.8.1,
+<a href="#s4.8.1-enum-classes">Enum classes</a>.</p><a name="emptyblocks"/><a name="s4.1.3-braces-empty-blocks"/>
+ <h4>4.1.3 Empty blocks: may be concise <a href="#s4.1.3-braces-empty-blocks"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>An empty block or block-like construct <em>may</em> be closed immediately after it is
+opened, with no characters or line break in between
+(<code class="prettyprint lang-java">{}</code>), <strong>unless</strong> it is part of a
+<em>multi-block statement</em> (one that directly contains multiple blocks:
+<code class="prettyprint lang-java">if/else-if/else</code> or
+<code class="prettyprint lang-java">try/catch/finally</code>).</p><p>Example:</p><pre class="prettyprint lang-java">
+ void doNothing() {}
+</pre><a name="s4.2-block-indentation"/>
+ <h3>4.2 Block indentation: +2 spaces <a href="#s4.2-block-indentation"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>Each time a new block or block-like construct is opened, the indent increases by two
+spaces. When the block ends, the indent returns to the previous indent level. The indent level
+applies to both code and comments throughout the block. (See the example in Section 4.1.2,
+<a href="#s4.1.2-blocks-k-r-style">Nonempty blocks: K & R Style</a>.)</p><a name="s4.3-one-statement-per-line"/>
+ <h3>4.3 One statement per line <a href="#s4.3-one-statement-per-line"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>Each statement is followed by a line-break.</p><a name="columnlimit"/><a name="s4.4-column-limit"/>
+ <h3>4.4 Column limit: 80 <a href="#s4.4-column-limit"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>
+ Projects should have a column limit of 80 characters.
+
+Except as noted below, any line that would exceed this limit must be line-wrapped, as explained in
+Section 4.5, <a href="#s4.5-line-wrapping">Line-wrapping</a>.
+</p><p><strong>Exceptions:</strong></p><ol><li>Lines where obeying the column limit is not possible (for example, a long URL in Javadoc,
+ or a long JSNI method reference).</li><li><code class="prettyprint lang-java">package</code> and
+ <code class="prettyprint lang-java">import</code> statements (see Sections
+ 3.2 <a href="#s3.2-package-statement">Package statement</a> and
+ 3.3 <a href="#s3.3-import-statements">Import statements</a>).</li><li>Command lines in a comment that may be cut-and-pasted into a shell.</li></ol><a name="s4.5-line-wrapping"/>
+ <h3>4.5 Line-wrapping <a href="#s4.5-line-wrapping"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p class="terminology"><strong>Terminology Note:</strong> When code that might otherwise legally
+occupy a single line is divided into multiple lines, typically to avoid overflowing the column
+limit, this activity is called
+<em>line-wrapping</em>.</p><p>There is no comprehensive, deterministic formula showing <em>exactly</em> how to line-wrap in
+every situation. Very often there are several valid ways to line-wrap the same piece of code.</p><p class="tip"><strong>Tip:</strong> Extracting a method or local variable may solve the problem
+without the need to line-wrap.</p><a name="s4.5.1-line-wrapping-where-to-break"/>
+ <h4>4.5.1 Where to break <a href="#s4.5.1-line-wrapping-where-to-break"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>The prime directive of line-wrapping is: prefer to break at a
+<strong>higher syntactic level</strong>. Also:</p><ol><li>When a line is broken at a <em>non-assignment</em> operator the break comes <em>before</em>
+ the symbol. (Note that this is not the same practice used in Google style for other languages,
+ such as C++ and JavaScript.)
+ <ul><li>This also applies to the following "operator-like" symbols: the dot separator
+ (<code class="prettyprint lang-java">.</code>), the ampersand in type bounds
+ (<code class="prettyprint lang-java"><T extends Foo & Bar></code>), and the pipe in
+ catch blocks
+ (<code class="prettyprint lang-java">catch (FooException | BarException e)</code>).</li></ul></li><li>When a line is broken at an <em>assignment</em> operator the break typically comes
+ <em>after</em> the symbol, but either way is acceptable.
+ <ul><li>This also applies to the "assignment-operator-like" colon in an enhanced
+ <code class="prettyprint lang-java">for</code> ("foreach") statement.</li></ul></li><li>A method or constructor name stays attached to the open parenthesis
+ (<code class="prettyprint lang-java">(</code>) that follows it.</li><li>A comma (<code class="prettyprint lang-java">,</code>) stays attached to the token that
+ precedes it.</li></ol><a name="indentation"/><a name="s4.5.2-line-wrapping-indent"/>
+ <h4>4.5.2 Indent continuation lines at least +4 spaces <a href="#s4.5.2-line-wrapping-indent"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>When line-wrapping, each line after the first (each <em>continuation line</em>) is indented
+at least +4 from the original line.</p><p>When there are multiple continuation lines, indentation may be varied beyond +4 as
+desired. In general, two continuation lines use the same indentation level if and only if they
+begin with syntactically parallel elements.</p><p>Section 4.6.3 on <a href="#s4.6.3-horizontal-alignment">Horizontal alignment</a> addresses
+the discouraged practice of using a variable number of spaces to align certain tokens with
+previous lines.</p><a name="s4.6-whitespace"/>
+ <h3>4.6 Whitespace <a href="#s4.6-whitespace"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <a name="s4.6.1-vertical-whitespace"/>
+ <h4>4.6.1 Vertical Whitespace <a href="#s4.6.1-vertical-whitespace"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>A single blank line appears:</p><ol><li><em>Between</em> consecutive members (or initializers) of a class: fields, constructors,
+ methods, nested classes, static initializers, instance initializers.
+ <ul><li><span class="exception"><strong>Exception:</strong> A blank line between two consecutive
+ fields (having no other code between them) is optional. Such blank lines are used as needed to
+ create <em>logical groupings</em> of fields.</span></li></ul></li><li>Within method bodies, as needed to create <em>logical groupings</em> of statements.</li><li><em>Optionally</em> before the first member or after the last member of the class (neither
+ encouraged nor discouraged).</li><li>As required by other sections of this document (such as Section 3.3,
+ <a href="#s3.3-import-statements">Import statements</a>).</li></ol><p><em>Multiple</em> consecutive blank lines are permitted, but never required (or encouraged).</p><a name="s4.6.2-horizontal-whitespace"/>
+ <h4>4.6.2 Horizontal whitespace <a href="#s4.6.2-horizontal-whitespace"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Beyond where required by the language or other style rules, and apart from literals, comments and
+Javadoc, a single ASCII space also appears in the following places <strong>only</strong>.</p><ol><li>Separating any reserved word, such as
+ <code class="prettyprint lang-java">if</code>,
+ <code class="prettyprint lang-java">for</code> or
+ <code class="prettyprint lang-java">catch</code>, from an open parenthesis
+ (<code class="prettyprint lang-java">(</code>)
+ that follows it on that line</li><li>Separating any reserved word, such as
+ <code class="prettyprint lang-java">else</code> or
+ <code class="prettyprint lang-java">catch</code>, from a closing curly brace
+ (<code class="prettyprint lang-java">}</code>) that precedes it on that line</li><li>Before any open curly brace
+ (<code class="prettyprint lang-java">{</code>), with two exceptions:
+ <ul><li><code class="prettyprint lang-java">@SomeAnnotation({a, b})</code> (no space is used)</li><li><code class="prettyprint lang-java">String[][] x = {{"foo"}};</code> (no space is required
+ between <code class="prettyprint lang-java">{{</code>, by item 8 below)</li></ul></li><li>On both sides of any binary or ternary operator. This also applies to the following
+ "operator-like" symbols:
+ <ul><li>the ampersand in a conjunctive type bound:
+ <code class="prettyprint lang-java"><T extends Foo & Bar></code></li><li>the pipe for a catch block that handles multiple exceptions:
+ <code class="prettyprint lang-java">catch (FooException | BarException e)</code></li><li>the colon (<code class="prettyprint lang-java">:</code>) in an enhanced
+ <code class="prettyprint lang-java">for</code> ("foreach") statement</li></ul></li><li>After <code class="prettyprint lang-java">,:;</code> or the closing parenthesis
+ (<code class="prettyprint lang-java">)</code>) of a cast</li><li>On both sides of the double slash (<code class="prettyprint lang-java">//</code>) that
+ begins an end-of-line comment. Here, multiple spaces are allowed, but not required.</li><li>Between the type and variable of a declaration:
+ <code class="prettyprint lang-java">List<String> list</code></li><li><em>Optional</em> just inside both braces of an array initializer
+ <ul><li><code class="prettyprint lang-java">new int[] {5, 6}</code> and
+ <code class="prettyprint lang-java">new int[] { 5, 6 }</code> are both valid</li></ul></li></ol><p class="note"><strong>Note:</strong> This rule never requires or forbids additional space at the
+start or end of a line, only <em>interior</em> space.</p><a name="s4.6.3-horizontal-alignment"/>
+ <h4>4.6.3 Horizontal alignment: never required <a href="#s4.6.3-horizontal-alignment"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p class="terminology"><strong>Terminology Note:</strong> <em>Horizontal alignment</em> is the
+practice of adding a variable number of additional spaces in your code with the goal of making
+certain tokens appear directly below certain other tokens on previous lines.</p><p>This practice is permitted, but is <strong>never required</strong> by Google Style. It is not
+even required to <em>maintain</em> horizontal alignment in places where it was already used.</p><p>Here is an example without alignment, then using alignment:</p><pre class="prettyprint lang-java">
+private int x; // this is fine
+private Color color; // this too
+
+private int x; // permitted, but future edits
+private Color color; // may leave it unaligned
+</pre><p class="tip"><strong>Tip:</strong> Alignment can aid readability, but it creates problems for
+future maintenance. Consider a future change that needs to touch just one line. This change may
+leave the formerly-pleasing formatting mangled, and that is <strong>allowed</strong>. More often
+it prompts the coder (perhaps you) to adjust whitespace on nearby lines as well, possibly
+triggering a cascading series of reformattings. That one-line change now has a "blast radius."
+This can at worst result in pointless busywork, but at best it still corrupts version history
+information, slows down reviewers and exacerbates merge conflicts.</p><a name="parentheses"/><a name="s4.7-grouping-parentheses"/>
+ <h3>4.7 Grouping parentheses: recommended <a href="#s4.7-grouping-parentheses"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>Optional grouping parentheses are omitted only when author and reviewer agree that there is no
+reasonable chance the code will be misinterpreted without them, nor would they have made the code
+easier to read. It is <em>not</em> reasonable to assume that every reader has the entire Java
+operator precedence table memorized.</p><a name="s4.8-specific-constructs"/>
+ <h3>4.8 Specific constructs <a href="#s4.8-specific-constructs"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <a name="s4.8.1-enum-classes"/>
+ <h4>4.8.1 Enum classes <a href="#s4.8.1-enum-classes"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>After each comma that follows an enum constant, a line-break is optional.</p><p>An enum class with no methods and no documentation on its constants may optionally be formatted
+as if it were an array initializer (see Section 4.8.3.1 on
+<a href="#s4.8.3.1-array-initializers">array initializers</a>).</p><pre class="prettyprint lang-java">
+private enum Suit { CLUBS, HEARTS, SPADES, DIAMONDS }
+</pre><p>Since enum classes <em>are classes</em>, all other rules for formatting classes apply.</p><a name="localvariables"/><a name="s4.8.2-variable-declarations"/>
+ <h4>4.8.2 Variable declarations <a href="#s4.8.2-variable-declarations"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <a name="s4.8.2.1-variables-per-declaration"/>
+ <h5>4.8.2.1 One variable per declaration <a href="#s4.8.2.1-variables-per-declaration"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>Every variable declaration (field or local) declares only one variable: declarations such as
+<code class="badcode">int a, b;</code> are not used.</p><a name="s4.8.2.2-variables-limited-scope"/>
+ <h5>4.8.2.2 Declared when needed, initialized as soon as
+possible <a href="#s4.8.2.2-variables-limited-scope"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>Local variables are <strong>not</strong> habitually declared at the start of their containing
+block or block-like construct. Instead, local variables are declared close to the point they are
+first used (within reason), to minimize their scope. Local variable declarations typically have
+initializers, or are initialized immediately after declaration.</p><a name="s4.8.3-arrays"/>
+ <h4>4.8.3 Arrays <a href="#s4.8.3-arrays"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <a name="s4.8.3.1-array-initializers"/>
+ <h5>4.8.3.1 Array initializers: can be "block-like" <a href="#s4.8.3.1-array-initializers"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>Any array initializer may <em>optionally</em> be formatted as if it were a "block-like
+construct." For example, the following are all valid (<strong>not</strong> an exhaustive
+list):</p><pre class="prettyprint lang-java">
+new int[] { new int[] {
+ 0, 1, 2, 3 0,
+} 1,
+ 2,
+new int[] { 3,
+ 0, 1, }
+ 2, 3
+} new int[]
+ {0, 1, 2, 3}
+</pre><a name="s4.8.3.2-array-declarations"/>
+ <h5>4.8.3.2 No C-style array declarations <a href="#s4.8.3.2-array-declarations"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>The square brackets form a part of the <em>type</em>, not the variable:
+<code class="prettyprint lang-java">String[] args</code>, not
+<code class="badcode">String args[]</code>.</p><a name="s4.8.4-switch"/>
+ <h4>4.8.4 Switch statements <a href="#s4.8.4-switch"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p class="terminology"><strong>Terminology Note:</strong> Inside the braces of a
+<em>switch block</em> are one or more <em>statement groups</em>. Each statement group consists of
+one or more <em>switch labels</em> (either <code class="prettyprint lang-java">case FOO:</code> or
+<code class="prettyprint lang-java">default:</code>), followed by one or more statements.</p><a name="s4.8.4.1-switch-indentation"/>
+ <h5>4.8.4.1 Indentation <a href="#s4.8.4.1-switch-indentation"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>As with any other block, the contents of a switch block are indented +2.</p><p>After a switch label, a newline appears, and the indentation level is increased +2, exactly as
+if a block were being opened. The following switch label returns to the previous indentation
+level, as if a block had been closed.</p><a name="fallthrough"/><a name="s4.8.4.2-switch-fall-through"/>
+ <h5>4.8.4.2 Fall-through: commented <a href="#s4.8.4.2-switch-fall-through"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>Within a switch block, each statement group either terminates abruptly (with a
+<code class="prettyprint lang-java">break</code>,
+<code class="prettyprint lang-java">continue</code>,
+<code class="prettyprint lang-java">return</code> or thrown exception), or is marked with a comment
+to indicate that execution will or <em>might</em> continue into the next statement group. Any
+comment that communicates the idea of fall-through is sufficient (typically
+<code class="prettyprint lang-java">// fall through</code>). This special comment is not required in
+the last statement group of the switch block. Example:</p><pre class="prettyprint lang-java">
+switch (input) {
+ case 1:
+ case 2:
+ prepareOneOrTwo();
+ // fall through
+ case 3:
+ handleOneTwoOrThree();
+ break;
+ default:
+ handleLargeNumber(input);
+}
+</pre><a name="s4.8.4.3-switch-default"/>
+ <h5>4.8.4.3 The default case is present <a href="#s4.8.4.3-switch-default"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>Each switch statement includes a <code class="prettyprint lang-java">default</code> statement
+group, even if it contains no code.</p><a name="annotations"/><a name="s4.8.5-annotations"/>
+ <h4>4.8.5 Annotations <a href="#s4.8.5-annotations"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Annotations applying to a class, method or constructor appear immediately after the
+documentation block, and each annotation is listed on a line of its own (that is, one annotation
+per line). These line breaks do not constitute line-wrapping (Section
+4.5, <a href="#s4.5-line-wrapping">Line-wrapping</a>), so the indentation level is not
+increased. Example:</p><pre class="prettyprint lang-java">
+@Override
+@Nullable
+public String getNameIfPresent() { ... }
+</pre><p class="exception"><strong>Exception:</strong> A <em>single</em> parameterless annotation
+<em>may</em> instead appear together with the first line of the signature, for example:</p><pre class="prettyprint lang-java">
+@Override public int hashCode() { ... }
+</pre><p>Annotations applying to a field also appear immediately after the documentation block, but in
+this case, <em>multiple</em> annotations (possibly parameterized) may be listed on the same line;
+for example:</p><pre class="prettyprint lang-java">
+@Partial @Mock DataLoader loader;
+</pre><p>There are no specific rules for formatting parameter and local variable annotations.</p><a name="comments"/><a name="s4.8.6-comments"/>
+ <h4>4.8.6 Comments <a href="#s4.8.6-comments"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <a name="s4.8.6.1-block-comment-style"/>
+ <h5>4.8.6.1 Block comment style <a href="#s4.8.6.1-block-comment-style"><img height="21" width="21" src="javaguidelink.png"/></a></h5>
+ <p>Block comments are indented at the same level as the surrounding code. They may be in
+<code class="prettyprint lang-java">/* ... */</code> style or
+<code class="prettyprint lang-java">// ...</code> style. For multi-line
+<code class="prettyprint lang-java">/* ... */</code> comments, subsequent lines must start with
+<code>*</code> aligned with the <code>*</code> on the previous line.</p><pre class="prettyprint lang-java">
+/*
+ * This is // And so /* Or you can
+ * okay. // is this. * even do this. */
+ */
+</pre><p>Comments are not enclosed in boxes drawn with asterisks or other characters.</p><p class="tip"><strong>Tip:</strong> When writing multi-line comments, use the
+<code class="prettyprint lang-java">/* ... */</code> style if you want automatic code formatters to
+re-wrap the lines when necessary (paragraph-style). Most formatters don't re-wrap lines in
+<code class="prettyprint lang-java">// ...</code> style comment blocks.</p><a name="modifiers"/><a name="s4.8.7-modifiers"/>
+ <h4>4.8.7 Modifiers <a href="#s4.8.7-modifiers"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Class and member modifiers, when present, appear in the order
+recommended by the Java Language Specification:
+</p><pre>
+public protected private abstract static final transient volatile synchronized native strictfp
+</pre><a name="s4.8.8-numeric-literals"/>
+ <h4>4.8.8 Numeric Literals <a href="#s4.8.8-numeric-literals"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p><code>long</code>-valued integer literals use an uppercase <code>L</code> suffix, never
+lowercase (to avoid confusion with the digit <code>1</code>). For example, <code>3000000000L</code>
+rather than <code class="badcode">3000000000l</code>.</p><a name="naming"/><a name="s5-naming"/>
+ <h2>5 Naming <a href="#s5-naming"><img height="21" width="21" src="javaguidelink.png"/></a></h2>
+ <a name="s5.1-identifier-names"/>
+ <h3>5.1 Rules common to all identifiers <a href="#s5.1-identifier-names"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>Identifiers use only ASCII letters and digits, and in two cases noted below, underscores. Thus
+each valid identifier name is matched by the regular expression <code>\w+</code> .</p><p> In Google Style special prefixes or
+suffixes, like those seen in the examples <code class="badcode">name_</code>,
+<code class="badcode">mName</code>, <code class="badcode">s_name</code> and
+<code class="badcode">kName</code>, are <strong>not</strong> used.
+For WPILib, we do make one exception to this rule for non-constant field name.</p><a name="s5.2-specific-identifier-names"/>
+ <h3>5.2 Rules by identifier type <a href="#s5.2-specific-identifier-names"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <a name="s5.2.1-package-names"/>
+ <h4>5.2.1 Package names <a href="#s5.2.1-package-names"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Package names are all lowercase, with consecutive words simply concatenated together (no
+underscores). For example, <code>com.example.deepspace</code>, not
+<code class="badcode">com.example.deepSpace</code> or
+<code class="badcode">com.example.deep_space</code>.</p><a name="s5.2.2-class-names"/>
+ <h4>5.2.2 Class names <a href="#s5.2.2-class-names"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Class names are written in <a href="#s5.3-camel-case">UpperCamelCase</a>.</p><p>Class names are typically nouns or noun phrases. For example,
+<code class="prettyprint lang-java">Character</code> or
+<code class="prettyprint lang-java">ImmutableList</code>. Interface names may also be nouns or
+noun phrases (for example, <code class="prettyprint lang-java">List</code>), but may sometimes be
+adjectives or adjective phrases instead (for example,
+<code class="prettyprint lang-java">Readable</code>).</p><p>There are no specific rules or even well-established conventions for naming annotation types.</p><p><em>Test</em> classes are named starting with the name of the class they are testing, and ending
+with <code class="prettyprint lang-java">Test</code>. For example,
+<code class="prettyprint lang-java">HashTest</code> or
+<code class="prettyprint lang-java">HashIntegrationTest</code>.</p><a name="s5.2.3-method-names"/>
+ <h4>5.2.3 Method names <a href="#s5.2.3-method-names"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Method names are written in <a href="#s5.3-camel-case">lowerCamelCase</a>.</p><p>Method names are typically verbs or verb phrases. For example,
+<code class="prettyprint lang-java">sendMessage</code> or
+<code class="prettyprint lang-java">stop</code>.</p><p>Underscores may appear in JUnit <em>test</em> method names to separate logical components of the
+name. One typical pattern is <code>test<i><MethodUnderTest></i>_<i><state></i></code>,
+for example <code class="prettyprint lang-java">testPop_emptyStack</code>. There is no One Correct
+Way to name test methods.</p><a name="constants"/><a name="s5.2.4-constant-names"/>
+ <h4>5.2.4 Constant names <a href="#s5.2.4-constant-names"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Constant names use <code class="prettyprint lang-java">CONSTANT_CASE</code>: all uppercase
+letters, with words separated by underscores. But what <em>is</em> a constant, exactly?</p><p>Every constant is a static final field, but not all static final fields are constants. Before
+choosing constant case, consider whether the field really <em>feels like</em> a constant. For
+example, if any of that instance's observable state can change, it is almost certainly not a
+constant. Merely <em>intending</em> to never mutate the object is generally not
+enough. Examples:</p><pre class="prettyprint lang-java">
+// Constants
+static final int NUMBER = 5;
+static final ImmutableList<String> NAMES = ImmutableList.of("Ed", "Ann");
+static final Joiner COMMA_JOINER = Joiner.on(','); // because Joiner is immutable
+static final SomeMutableType[] EMPTY_ARRAY = {};
+enum SomeEnum { ENUM_CONSTANT }
+
+// Not constants
+static String nonFinal = "non-final";
+final String nonStatic = "non-static";
+static final Set<String> mutableCollection = new HashSet<String>();
+static final ImmutableSet<SomeMutableType> mutableElements = ImmutableSet.of(mutable);
+static final Logger logger = Logger.getLogger(MyClass.getName());
+static final String[] nonEmptyArray = {"these", "can", "change"};
+</pre><p>These names are typically nouns or noun phrases.</p><a name="s5.2.5-non-constant-field-names"/>
+ <h4>5.2.5 Non-constant field names <a href="#s5.2.5-non-constant-field-names"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Non-constant field names (static or otherwise) are written
+in <a href="#s5.3-camel-case">lowerCamelCase</a> with a preceding <code class="prettyprint lang-java">m_</code>.</p>
+<p>These names are typically nouns or noun phrases. For example,
+<code class="prettyprint lang-java">m_computedValues</code> or
+<code class="prettyprint lang-java">m_index</code>.</p><a name="s5.2.6-parameter-names"/>
+ <h4>5.2.6 Parameter names <a href="#s5.2.6-parameter-names"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Parameter names are written in <a href="#s5.3-camel-case">lowerCamelCase</a>.</p><p>One-character parameter names should be avoided.</p><a name="s5.2.7-local-variable-names"/>
+ <h4>5.2.7 Local variable names <a href="#s5.2.7-local-variable-names"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Local variable names are written in <a href="#s5.3-camel-case">lowerCamelCase</a>, and can be
+abbreviated more liberally than other types of names.</p><p>However, one-character names should be avoided, except for temporary and looping variables.</p><p>Even when final and immutable, local variables are not considered to be constants, and should not
+be styled as constants.</p><a name="s5.2.8-type-variable-names"/>
+ <h4>5.2.8 Type variable names <a href="#s5.2.8-type-variable-names"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Each type variable is named in one of two styles:</p><ul><li>A single capital letter, optionally followed by a single numeral (such as
+ <code class="prettyprint lang-java">E</code>, <code class="prettyprint lang-java">T</code>,
+ <code class="prettyprint lang-java">X</code>, <code class="prettyprint lang-java">T2</code>)
+ </li><li>A name in the form used for classes (see Section 5.2.2,
+ <a href="#s5.2.2-class-names">Class names</a>), followed by the capital letter
+ <code class="prettyprint lang-java">T</code> (examples:
+ <code class="prettyprint lang-java">RequestT</code>,
+ <code class="prettyprint lang-java">FooBarT</code>).</li></ul><a name="acronyms"/><a name="camelcase"/><a name="s5.3-camel-case"/>
+ <h3>5.3 Camel case: defined <a href="#s5.3-camel-case"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>Sometimes there is more than one reasonable way to convert an English phrase into camel case,
+such as when acronyms or unusual constructs like "IPv6" or "iOS" are present. To improve
+predictability, Google Style specifies the following (nearly) deterministic scheme.</p><p>Beginning with the prose form of the name:</p><ol><li>Convert the phrase to plain ASCII and remove any apostrophes. For example, "Müller's
+ algorithm" might become "Muellers algorithm".</li><li>Divide this result into words, splitting on spaces and any remaining punctuation (typically
+ hyphens).
+
+ <ul><li><em>Recommended:</em> if any word already has a conventional camel-case appearance in common
+ usage, split this into its constituent parts (e.g., "AdWords" becomes "ad words"). Note
+ that a word such as "iOS" is not really in camel case <em>per se</em>; it defies <em>any</em>
+ convention, so this recommendation does not apply.</li></ul></li><li>Now lowercase <em>everything</em> (including acronyms), then uppercase only the first
+ character of:
+ <ul><li>... each word, to yield <em>upper camel case</em>, or</li><li>... each word except the first, to yield <em>lower camel case</em></li></ul></li><li>Finally, join all the words into a single identifier.</li></ol><p>Note that the casing of the original words is almost entirely disregarded. Examples:</p><table><tr><th>Prose form</th><th>Correct</th><th>Incorrect</th></tr><tr><td>"XML HTTP request"</td><td><code class="prettyprint lang-java">XmlHttpRequest</code></td><td><code class="badcode">XMLHTTPRequest</code></td></tr><tr><td>"new customer ID"</td><td><code class="prettyprint lang-java">newCustomerId</code></td><td><code class="badcode">newCustomerID</code></td></tr><tr><td>"inner stopwatch"</td><td><code class="prettyprint lang-java">innerStopwatch</code></td><td><code class="badcode">innerStopWatch</code></td></tr><tr><td>"supports IPv6 on iOS?"</td><td><code class="prettyprint lang-java">supportsIpv6OnIos</code></td><td><code class="badcode">supportsIPv6OnIOS</code></td></tr><tr><td>"YouTube importer"</td><td><code class="prettyprint lang-java">YouTubeImporter</code><br/><code class="prettyprint lang-java">YoutubeImporter</code>*</td><td/></tr></table><p>*Acceptable, but not recommended.</p><p class="note"><strong>Note:</strong> Some words are ambiguously hyphenated in the English
+language: for example "nonempty" and "non-empty" are both correct, so the method names
+<code class="prettyprint lang-java">checkNonempty</code> and
+<code class="prettyprint lang-java">checkNonEmpty</code> are likewise both correct.</p><a name="s6-programming-practices"/>
+ <h2>6 Programming Practices <a href="#s6-programming-practices"><img height="21" width="21" src="javaguidelink.png"/></a></h2>
+ <a name="s6.1-override-annotation"/>
+ <h3>6.1 @Override: always used <a href="#s6.1-override-annotation"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>A method is marked with the <code class="prettyprint lang-java">@Override</code> annotation
+whenever it is legal. This includes a class method overriding a superclass method, a class method
+implementing an interface method, and an interface method respecifying a superinterface
+method.</p><p class="exception"><strong>Exception:</strong><code class="prettyprint lang-java">@Override</code> may be omitted when the parent method is
+<code class="prettyprint lang-java">@Deprecated</code>.</p><a name="caughtexceptions"/><a name="s6.2-caught-exceptions"/>
+ <h3>6.2 Caught exceptions: not ignored <a href="#s6.2-caught-exceptions"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>Except as noted below, it is very rarely correct to do nothing in response to a caught
+exception. (Typical responses are to log it, or if it is considered "impossible", rethrow it as an
+<code class="prettyprint lang-java">AssertionError</code>.)</p><p>When it truly is appropriate to take no action whatsoever in a catch block, the reason this is
+justified is explained in a comment.</p><pre class="prettyprint lang-java">
+try {
+ int i = Integer.parseInt(response);
+ return handleNumericResponse(i);
+} catch (NumberFormatException ok) {
+ // it's not numeric; that's fine, just continue
+}
+return handleTextResponse(response);
+</pre><p class="exception"><strong>Exception:</strong> In tests, a caught exception may be ignored
+without comment <em>if</em> it is named <code class="prettyprint lang-java">expected</code>. The
+following is a very common idiom for ensuring that the method under test <em>does</em> throw an
+exception of the expected type, so a comment is unnecessary here.</p><pre class="prettyprint lang-java">
+try {
+ emptyStack.pop();
+ fail();
+} catch (NoSuchElementException expected) {
+}
+</pre><a name="s6.3-static-members"/>
+ <h3>6.3 Static members: qualified using class <a href="#s6.3-static-members"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>When a reference to a static class member must be qualified, it is qualified with that class's
+name, not with a reference or expression of that class's type.</p><pre class="prettyprint lang-java">
+Foo aFoo = ...;
+Foo.aStaticMethod(); // good
+<span class="badcode">aFoo.aStaticMethod();</span> // bad
+<span class="badcode">somethingThatYieldsAFoo().aStaticMethod();</span> // very bad
+</pre><a name="finalizers"/><a name="s6.4-finalizers"/>
+ <h3>6.4 Finalizers: not used <a href="#s6.4-finalizers"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>It is <strong>extremely rare</strong> to override <code class="prettyprint lang-java">Object.finalize</code>.</p><p class="tip"><strong>Tip:</strong> Don't do it. If you absolutely must, first read and understand
+<a href="http://books.google.com/books?isbn=8131726592"><em>Effective Java</em></a>
+Item 7, "Avoid Finalizers," very carefully, and <em>then</em> don't do it.</p><a name="javadoc"/><a name="s7-javadoc"/>
+ <h2>7 Javadoc <a href="#s7-javadoc"><img height="21" width="21" src="javaguidelink.png"/></a></h2>
+ <a name="s7.1-javadoc-formatting"/>
+ <h3>7.1 Formatting <a href="#s7.1-javadoc-formatting"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <a name="s7.1.1-javadoc-multi-line"/>
+ <h4>7.1.1 General form <a href="#s7.1.1-javadoc-multi-line"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>The <em>basic</em> formatting of Javadoc blocks is as seen in this example:</p><pre class="prettyprint lang-java">
+/**
+ * Multiple lines of Javadoc text are written here,
+ * wrapped normally...
+ */
+public int method(String p1) { ... }
+</pre><p>... or in this single-line example:</p><pre class="prettyprint lang-java">
+/** An especially short bit of Javadoc. */
+</pre><p>The basic form is always acceptable. The single-line form may be substituted when there are no
+at-clauses present, and the entirety of the Javadoc block (including comment markers) can fit on a
+single line.</p><a name="s7.1.2-javadoc-paragraphs"/>
+ <h4>7.1.2 Paragraphs <a href="#s7.1.2-javadoc-paragraphs"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>One blank line—that is, a line containing only the aligned leading asterisk
+(<code>*</code>)—appears between paragraphs, and before the group of "at-clauses" if
+present. Each paragraph but the first has <code><p></code> immediately before the first word,
+with no space after.</p><a name="s7.1.3-javadoc-at-clauses"/>
+ <h4>7.1.3 At-clauses <a href="#s7.1.3-javadoc-at-clauses"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Any of the standard "at-clauses" that are used appear in the order <code>@param</code>,
+<code>@return</code>, <code>@throws</code>, <code>@deprecated</code>, and these four types never
+appear with an empty description. When an at-clause doesn't fit on a single line, continuation lines
+are indented four (or more) spaces from the position of the <code>@</code>.
+</p><a name="s7.2-summary-fragment"/>
+ <h3>7.2 The summary fragment <a href="#s7.2-summary-fragment"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>The Javadoc for each class and member begins with a brief <strong>summary fragment</strong>. This
+fragment is very important: it is the only part of the text that appears in certain contexts such as
+class and method indexes.</p><p>This is a fragment—a noun phrase or verb phrase, not a complete sentence. It does
+<strong>not</strong> begin with <code class="badcode">A {@code Foo} is a...</code>, or
+<code class="badcode">This method returns...</code>, nor does it form a complete imperative sentence
+like <code class="badcode">Save the record.</code>. However, the fragment is capitalized and
+punctuated as if it were a complete sentence.</p><p class="tip"><strong>Tip:</strong> A common mistake is to write simple Javadoc in the form
+<code class="badcode">/** @return the customer ID */</code>. This is incorrect, and should be
+changed to <code class="prettyprint lang-java">/** Returns the customer ID. */</code>.</p><a name="s7.3.3-javadoc-optional"/><a name="s7.3-javadoc-where-required"/>
+ <h3>7.3 Where Javadoc is used <a href="#s7.3-javadoc-where-required"><img height="21" width="21" src="javaguidelink.png"/></a></h3>
+ <p>At the <em>minimum</em>, Javadoc is present for every
+<code class="prettyprint lang-java">public</code> class, and every
+<code class="prettyprint lang-java">public</code> or
+<code class="prettyprint lang-java">protected</code> member of such a class, with a few exceptions
+noted below.</p><p>Other classes and members still have Javadoc <em>as needed</em>. Whenever an implementation
+comment would be used to define the overall purpose or behavior of a class, method or field, that
+comment is written as Javadoc instead. (It's more uniform, and more tool-friendly.)</p><a name="s7.3.1-javadoc-exception-self-explanatory"/>
+ <h4>7.3.1 Exception: self-explanatory methods <a href="#s7.3.1-javadoc-exception-self-explanatory"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Javadoc is optional for "simple, obvious" methods like
+<code class="prettyprint lang-java">getFoo</code>, in cases where there <em>really and truly</em> is
+nothing else worthwhile to say but "Returns the foo".</p><p class="note"><strong>Important:</strong> it is not appropriate to cite this exception to justify
+omitting relevant information that a typical reader might need to know. For example, for a method
+named <code class="prettyprint lang-java">getCanonicalName</code>, don't omit its documentation
+(with the rationale that it would say only
+<code class="badcode">/** Returns the canonical name. */</code>) if a typical reader may have no idea
+what the term "canonical name" means!</p><a name="s7.3.2-javadoc-exception-overrides"/>
+ <h4>7.3.2 Exception: overrides <a href="#s7.3.2-javadoc-exception-overrides"><img height="21" width="21" src="javaguidelink.png"/></a></h4>
+ <p>Javadoc is not always present on a method that overrides a supertype method.
+</p></div> <hr/>
+ <div class="change">Last changed: March 21, 2014</div>
+</body>
+</html>