src/xdocs/config_misc.xml

<?xml version="1.0" encoding="UTF-8"?>

<document xmlns="http://maven.apache.org/XDOC/2.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/XDOC/2.0 http://maven.apache.org/xsd/xdoc-2.0.xsd">

  <head>
    <title>Miscellaneous</title>
    <script type="text/javascript"
            src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"/>
    <script type="text/javascript" src="js/anchors.js"/>
    <script type="text/javascript" src="js/google-analytics.js"/>
    <link rel="icon" href="images/favicon.png" type="image/x-icon" />
    <link rel="shortcut icon" href="images/favicon.ico" type="image/ico" />
  </head>

  <body>
    <section name="Content">
      <macro name="toc">
        <param name="fromDepth" value="1"/>
        <param name="toDepth" value="1"/>
      </macro>
    </section>

    <section name="ArrayTypeStyle">
      <subsection name="Description" id="ArrayTypeStyle_Description">
        <p>Since Checkstyle 3.1</p>
        <p>
          Checks the style of array type definitions.  Some like Java style:
          <code>public static void main(String[] args)</code> and some like
          C style: <code>public static void main(String args[])</code>.
        </p>
        <p>
          This check also enforces only Java style for method return types.
        </p>
      </subsection>

      <subsection name="Properties" id="ArrayTypeStyle_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>javaStyle</td>
            <td>
              Controls whether to enforce Java style (true) or C style (false).
            </td>
            <td><a href="property_types.html#boolean">Boolean</a></td>
            <td><code>true</code></td>
            <td>3.1</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="ArrayTypeStyle_Examples">
        <p>
          To configure the check to enforce Java style:
        </p>
        <source>
&lt;module name=&quot;ArrayTypeStyle&quot;/&gt;
        </source>
        <p>
          Example:
        </p>
        <source>
public class MyClass {
  int[] nums; // OK
  String strings[]; // violation

  char[] toCharArray() { // OK
    return null;
  }

  byte getData()[] { // violation
    return null;
  }
}
        </source>
        <p>
          To configure the check to enforce C style:
        </p>
        <source>
&lt;module name=&quot;ArrayTypeStyle&quot;&gt;
  &lt;property name=&quot;javaStyle&quot; value=&quot;false&quot;/&gt;
&lt;/module&gt;
        </source>
        <p>
          Example:
        </p>
        <source>
public class MyClass {
  int[] nums; // violation
  String strings[]; // OK

  char[] toCharArray() { // OK
    return null;
  }

  byte getData()[] { // violation
    return null;
  }
}
        </source>
        <p>
          Note that method return types must be Java style even when the check is configured
          to enforce C style. This is because function/method return types in C/C++ cannot be
          arrays, so there is no "C style" for such array types.
        </p>
      </subsection>

      <subsection name="Example of Usage" id="ArrayTypeStyle_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Agoogle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+ArrayTypeStyle">
            Google Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Asun_checks.xml+repo%3Acheckstyle%2Fcheckstyle+ArrayTypeStyle">
            Sun Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+ArrayTypeStyle">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="ArrayTypeStyle_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22array.type.style%22">
            array.type.style</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="ArrayTypeStyle_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="ArrayTypeStyle_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="AvoidEscapedUnicodeCharacters">
      <subsection name="Description" id="AvoidEscapedUnicodeCharacters_Description">
        <p>Since Checkstyle 5.8</p>
        <p>
          Restrict using
            <a href = "https://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html#jls-3.3">
          Unicode escapes</a> (e.g. \u221e).
          It is possible to allow using escapes for
          <a href="https://en.wiktionary.org/wiki/Appendix:Control_characters">
              non-printable(control) characters</a>.
          Also, this check can be configured to allow using escapes
          if trail comment is present. By the option it is possible to
          allow using escapes if literal contains only them.
        </p>
      </subsection>

       <subsection name="Properties" id="AvoidEscapedUnicodeCharacters_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>allowEscapesForControlCharacters</td>
            <td>Allow use escapes for non-printable(control) characters.</td>
            <td><a href="property_types.html#boolean">Boolean</a></td>
            <td>false</td>
            <td>5.8</td>
          </tr>
          <tr>
            <td>allowByTailComment</td>
            <td>Allow use escapes if trail comment is present.</td>
            <td><a href="property_types.html#boolean">Boolean</a></td>
            <td>false</td>
            <td>5.8</td>
          </tr>
          <tr>
            <td>allowIfAllCharactersEscaped</td>
            <td>Allow if all characters in literal are escaped.</td>
            <td><a href="property_types.html#boolean">Boolean</a></td>
            <td>false</td>
            <td>5.8</td>
          </tr>
          <tr>
            <td>allowNonPrintableEscapes</td>
            <td>Allow non-printable escapes.</td>
            <td><a href="property_types.html#boolean">Boolean</a></td>
            <td>false</td>
            <td>5.8</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="AvoidEscapedUnicodeCharacters_Examples">
       <p>
          Examples of using Unicode:
        </p>
        <source>
String unitAbbrev = "μs"; //Best: perfectly clear even without a comment.
String unitAbbrev = "\u03bcs"; //Poor: the reader has no idea what this is.
        </source>
        <p>
          An example of how to configure the check is:
        </p>
        <source>
&lt;module name=&quot;AvoidEscapedUnicodeCharacters&quot;/&gt;
        </source>
        <p>
          An example of non-printable(control) characters.
        </p>
        <source>
return '\ufeff' + content; // byte order mark
        </source>
        <p>
          An example of how to configure the check to allow using escapes
          for non-printable(control) characters:
        </p>
        <source>
&lt;module name="AvoidEscapedUnicodeCharacters"&gt;
  &lt;property name="allowEscapesForControlCharacters" value="true"/&gt;
&lt;/module&gt;
        </source>
        <p>
          Example of using escapes with trail comment:
        </p>
        <source>
String unitAbbrev = "\u03bcs"; // Greek letter mu, "s"
        </source>
        <p>
          An example of how to configure the check to allow using escapes
          if trail comment is present:
        </p>
        <source>
&lt;module name="AvoidEscapedUnicodeCharacters"&gt;
  &lt;property name="allowByTailComment" value="true"/&gt;
&lt;/module&gt;
        </source>
        <p>
          Example of using escapes if literal contains only them:
        </p>
        <source>
String unitAbbrev = "\u03bc\u03bc\u03bc";
        </source>
        <p>
          An example of how to configure the check to allow escapes
          if literal contains only them:
        </p>
        <source>
&lt;module name="AvoidEscapedUnicodeCharacters"&gt;
  &lt;property name="allowIfAllCharactersEscaped" value="true"/&gt;
&lt;/module&gt;
        </source>
        <p>
          An example of how to configure the check to allow non-printable escapes:
        </p>
        <source>
&lt;module name="AvoidEscapedUnicodeCharacters"&gt;
  &lt;property name="allowNonPrintableEscapes" value="true"/&gt;
&lt;/module&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="AvoidEscapedUnicodeCharacters_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Agoogle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+AvoidEscapedUnicodeCharacters">
            Google Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+AvoidEscapedUnicodeCharacters">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="AvoidEscapedUnicodeCharacters_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22forbid.escaped.unicode.char%22">
            forbid.escaped.unicode.char</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="AvoidEscapedUnicodeCharacters_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="AvoidEscapedUnicodeCharacters_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="CommentsIndentation">
      <subsection name="Description" id="CommentsIndentation_Description">
        <p>Since Checkstyle 6.10</p>
        <p>
          Controls the indentation between comments and surrounding code.
          Comments are indented at the same level as the surrounding code.
          Detailed info about such convention can be found
          <a href="styleguides/google-java-style-20170228.html#s4.8.6.1-block-comment-style">
          here</a>
        </p>
        <p>Please take a look at the following examples to understand how the check works:</p>

        <p>Example #1: Block comments.</p>
        <source>
1   /*
2    * it is Ok
3    */
4   boolean bool = true;
5
6     /* violation
7      * (block comment should have the same indentation level as line 9)
8      */
9   double d = 3.14;
        </source>
        <p>Example #2: Comment is placed at the end of the block and has previous statement.</p>
        <source>
1   public void foo1() {
2     foo2();
3     // it is OK
4   }
5
6   public void foo2() {
7     foo3();
8       // violation (comment should have the same indentation level as line 7)
9   }
        </source>
        <p>Example #3: Comment is used as a single line border to separate groups of methods.</p>
        <source>
1   /////////////////////////////// it is OK
2
3   public void foo7() {
4     int a = 0;
5   }
6
7     /////////////////////////////// violation (should have the same indentation level as line 9)
8
9   public void foo8() {}
        </source>
        <p>Example #4: Comment has distributed previous statement.</p>
        <source>
1   public void foo11() {
2     CheckUtil
3       .getFirstNode(new DetailAST())
4       .getFirstChild()
5       .getNextSibling();
6     // it is OK
7   }
8
9   public void foo12() {
10    CheckUtil
11      .getFirstNode(new DetailAST())
12      .getFirstChild()
13      .getNextSibling();
14              // violation (should have the same indentation level as line 10)
15  }
        </source>
        <p>
          Example #5: Single line block comment is placed within an empty code block.
          Note, if comment is placed at the end of the empty code block, we have Checkstyle's
          limitations to clearly detect user intention of explanation target - above or below. The
          only case we can assume as a violation is when a single line comment within the empty
          code block has indentation level that is lower than the indentation level of the closing
          right curly brace.
        </p>
        <source>
1   public void foo46() {
2     // comment
3     // block
4     // it is OK (we cannot clearly detect user intention of explanation target)
5   }
6
7   public void foo46() {
8  // comment
9  // block
10 // violation (comment should have the same indentation level as line 11)
11  }
        </source>
        <p>Example #6: 'fallthrough' comments and similar.</p>
        <source>
0   switch(a) {
1     case "1":
2       int k = 7;
3       // it is OK
4     case "2":
5       int k = 7;
6     // it is OK
7     case "3":
8       if (true) {}
9           // violation (should have the same indentation level as line 8 or 10)
10    case "4":
11    case "5": {
12      int a;
13    }
14    // fall through (it is OK)
15    case "12": {
16      int a;
17    }
18    default:
19      // it is OK
20  }
        </source>
        <p>Example #7: Comment is placed within a distributed statement.</p>
        <source>
1   String breaks = "J"
2   // violation (comment should have the same indentation level as line 3)
3       + "A"
4       // it is OK
5       + "V"
6       + "A"
7   // it is OK
8   ;
        </source>
        <p>
          Example #8: Comment is placed within an empty case block.
          Note, if comment is placed at the end of the empty case block, we have Checkstyle's
          limitations to clearly detect user intention of explanation target - above or below. The
          only case we can assume as a violation is when a single line comment within the empty case
          block has indentation level that is lower than the indentation level of the next case
          token.
        </p>
        <source>
1   case 4:
2     // it is OK
3   case 5:
4  // violation (should have the same indentation level as line 3 or 5)
5   case 6:
        </source>
        <p>Example #9: Single line block comment has previous and next statement.</p>
        <source>
1   String s1 = "Clean code!";
2      s.toString().toString().toString();
3   // single line
4   // block
5   // comment (it is OK)
6   int a = 5;
7
8   String s2 = "Code complete!";
9    s.toString().toString().toString();
10            // violation (should have the same indentation level as line 11)
11       // violation (should have the same indentation level as line 12)
12     // violation (should have the same indentation level as line 13)
13  int b = 18;
        </source>
        <p>Example #10: Comment within the block tries to describe the next code block.</p>
        <source>
1   public void foo42() {
2     int a = 5;
3     if (a == 5) {
4       int b;
5       // it is OK
6      } else if (a ==6) { ... }
7   }
8
9   public void foo43() {
10    try {
11      int a;
12     // Why do we catch exception here? - violation (should have the same indentation as line 11)
13     } catch (Exception e) { ... }
14  }
        </source>
      </subsection>
      <subsection name="Properties" id="CommentsIndentation_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
            <tr>
            <td>tokens</td>
            <td>tokens to check</td>
            <td>
              subset of tokens
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#SINGLE_LINE_COMMENT">
                SINGLE_LINE_COMMENT</a>,
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#BLOCK_COMMENT_BEGIN">
                BLOCK_COMMENT_BEGIN</a>.
            </td>
            <td>
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#SINGLE_LINE_COMMENT">
                SINGLE_LINE_COMMENT</a>,
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#BLOCK_COMMENT_BEGIN">
                BLOCK_COMMENT_BEGIN</a>.
            </td>
            <td>6.10</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="CommentsIndentation_Examples">
        <p>
          To configure the Check:
        </p>
        <source>
&lt;module name=&quot;CommentsIndentation&quot;/&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="CommentsIndentation_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Agoogle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+CommentsIndentation">
            Google Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+CommentsIndentation">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="CommentsIndentation_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks%2Findentation+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22comments.indentation.block%22">
            comments.indentation.block</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks%2Findentation+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22comments.indentation.single%22">
            comments.indentation.single</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="CommentsIndentation_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks.indentation
        </p>
      </subsection>

      <subsection name="Parent Module" id="CommentsIndentation_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="DescendantToken">
      <subsection name="Description" id="DescendantToken_Description">
        <p>Since Checkstyle 3.2</p>
        <p>
          Checks for restricted tokens beneath other tokens.
        </p>

        <p>
          WARNING: This is a very powerful and flexible check, but, at the
          same time, it is low-level and very implementation-dependent because
          its results depend on the grammar we use to build abstract syntax
          trees. Thus we recommend using other checks when they provide the
          desired functionality. Essentially, this check just works on the level
          of an abstract syntax tree and knows nothing about language structures.
        </p>
      </subsection>

      <subsection name="Properties" id="DescendantToken_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>limitedTokens</td>
            <td>set of tokens with limited occurrences as descendants</td>
            <td>
             subset of tokens
             <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html">TokenTypes</a>
            </td>
            <td/>
            <td>3.2</td>
          </tr>
          <tr>
            <td>minimumDepth</td>
            <td>the minimum depth for descendant counts</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>0</td>
            <td>3.2</td>
          </tr>
          <tr>
            <td>maximumDepth</td>
            <td>the maximum depth for descendant counts</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>java.lang.Integer.MAX_VALUE</td>
            <td>3.2</td>
          </tr>
          <tr>
            <td>minimumNumber</td>
            <td>a minimum count for descendants</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>0</td>
            <td>3.2</td>
          </tr>
          <tr>
            <td>maximumNumber</td>
            <td>a maximum count for descendants</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>java.lang.Integer.MAX_VALUE</td>
            <td>3.2</td>
          </tr>
          <tr>
            <td>sumTokenCounts</td>
            <td>
              whether the number of tokens found should be calculated
              from the sum of the individual token counts
            </td>
            <td><a href="property_types.html#boolean">Boolean</a></td>
            <td><code>false</code></td>
            <td>5.0</td>
          </tr>
          <tr>
            <td>minimumMessage</td>
            <td>error message when the minimum count is not reached</td>
            <td><a href="property_types.html#string">String</a></td>
            <td>null</td>
            <td>3.2</td>
          </tr>
          <tr>
            <td>maximumMessage</td>
            <td>error message when the maximum count is exceeded</td>
            <td><a href="property_types.html#string">String</a></td>
            <td>null</td>
            <td>3.2</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="DescendantToken_Examples">

        <p>Switch with no default:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="LITERAL_SWITCH"/&gt;
  &lt;property name="maximumDepth" value="2"/&gt;
  &lt;property name="limitedTokens" value="LITERAL_DEFAULT"/&gt;
  &lt;property name="minimumNumber" value="1"/&gt;
&lt;/module&gt;
        </source>

        <p>
          The condition in <code>for</code> performs no check:
        </p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="FOR_CONDITION"/&gt;
  &lt;property name="limitedTokens" value="EXPR"/&gt;
  &lt;property name="minimumNumber" value="1"/&gt;
&lt;/module&gt;
        </source>

        <p>
          Comparing <code>this</code> with <code>null</code> (i.e. <code>this ==
          null</code> and <code>this != null</code>):
        </p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="EQUAL,NOT_EQUAL"/&gt;
  &lt;property name="limitedTokens" value="LITERAL_THIS,LITERAL_NULL"/&gt;
  &lt;property name="maximumNumber" value="1"/&gt;
  &lt;property name="maximumDepth" value="1"/&gt;
  &lt;property name="sumTokenCounts" value="true"/&gt;
&lt;/module&gt;
        </source>

        <p>String literal equality check:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="EQUAL,NOT_EQUAL"/&gt;
  &lt;property name="limitedTokens" value="STRING_LITERAL"/&gt;
  &lt;property name="maximumNumber" value="0"/&gt;
  &lt;property name="maximumDepth" value="1"/&gt;
&lt;/module&gt;
        </source>

        <p>
          Assert statement may have side effects (formatted for browser
          display):
        </p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="LITERAL_ASSERT"/&gt;
  &lt;property name="limitedTokens" value="ASSIGN,DEC,INC,POST_DEC,
    POST_INC,PLUS_ASSIGN,MINUS_ASSIGN,STAR_ASSIGN,DIV_ASSIGN,MOD_ASSIGN,
    BSR_ASSIGN,SR_ASSIGN,SL_ASSIGN,BAND_ASSIGN,BXOR_ASSIGN,BOR_ASSIGN,
    METHOD_CALL"/&gt;
  &lt;property name="maximumNumber" value="0"/&gt;
&lt;/module&gt;
        </source>

        <p>
          The initialiser in <code>for</code> performs no setup (where a <code>while</code>
          statement could be used instead):
        </p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="FOR_INIT"/&gt;
  &lt;property name="limitedTokens" value="EXPR"/&gt;
  &lt;property name="minimumNumber" value="1"/&gt;
&lt;/module&gt;
        </source>

        <p>
          A switch within a switch:
        </p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="LITERAL_SWITCH"/&gt;
  &lt;property name="limitedTokens" value="LITERAL_SWITCH"/&gt;
  &lt;property name="maximumNumber" value="0"/&gt;
  &lt;property name="minimumDepth" value="1"/&gt;
&lt;/module&gt;
        </source>

        <p>A return statement from within a catch or finally block:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="LITERAL_FINALLY,LITERAL_CATCH"/&gt;
  &lt;property name="limitedTokens" value="LITERAL_RETURN"/&gt;
  &lt;property name="maximumNumber" value="0"/&gt;
&lt;/module&gt;
        </source>

        <p>A try statement within a catch or finally block:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="LITERAL_CATCH,LITERAL_FINALLY"/&gt;
  &lt;property name="limitedTokens" value="LITERAL_TRY"/&gt;
  &lt;property name="maximumNumber" value="0"/&gt;
&lt;/module&gt;
        </source>

        <p>Too many cases within a switch:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="LITERAL_SWITCH"/&gt;
  &lt;property name="limitedTokens" value="LITERAL_CASE"/&gt;
  &lt;property name="maximumDepth" value="2"/&gt;
  &lt;property name="maximumNumber" value="10"/&gt;
&lt;/module&gt;
        </source>

        <p>Too many local variables within a method:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="METHOD_DEF"/&gt;
  &lt;property name="limitedTokens" value="VARIABLE_DEF"/&gt;
  &lt;property name="maximumDepth" value="2"/&gt;
  &lt;property name="maximumNumber" value="10"/&gt;
&lt;/module&gt;
        </source>

        <p>Too many returns from within a method:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="METHOD_DEF"/&gt;
  &lt;property name="limitedTokens" value="LITERAL_RETURN"/&gt;
  &lt;property name="maximumNumber" value="3"/&gt;
&lt;/module&gt;
        </source>

        <p>Too many fields within an interface:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="INTERFACE_DEF"/&gt;
  &lt;property name="limitedTokens" value="VARIABLE_DEF"/&gt;
  &lt;property name="maximumDepth" value="2"/&gt;
  &lt;property name="maximumNumber" value="0"/&gt;
&lt;/module&gt;
        </source>

        <p>Limits the number of exceptions a method can throw:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="LITERAL_THROWS"/&gt;
  &lt;property name="limitedTokens" value="IDENT"/&gt;
  &lt;property name="maximumNumber" value="1"/&gt;
&lt;/module&gt;
        </source>

        <p>Limits the number of expressions in a method:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="METHOD_DEF"/&gt;
  &lt;property name="limitedTokens" value="EXPR"/&gt;
  &lt;property name="maximumNumber" value="200"/&gt;
&lt;/module&gt;
        </source>

        <p>Disallows empty statements:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="EMPTY_STAT"/&gt;
  &lt;property name="limitedTokens" value="EMPTY_STAT"/&gt;
  &lt;property name="maximumNumber" value="0"/&gt;
  &lt;property name="maximumDepth" value="0"/&gt;
  &lt;property name="maximumMessage"
    value="Empty statement is not allowed."/&gt;
&lt;/module&gt;
        </source>

        <p>Too many fields within a class:</p>
        <source>
&lt;module name="DescendantToken"&gt;
  &lt;property name="tokens" value="CLASS_DEF"/&gt;
  &lt;property name="limitedTokens" value="VARIABLE_DEF"/&gt;
  &lt;property name="maximumDepth" value="2"/&gt;
  &lt;property name="maximumNumber" value="10"/&gt;
&lt;/module&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="DescendantToken_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+DescendantToken">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="DescendantToken_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22descendant.token.max%22">
            descendant.token.max</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22descendant.token.min%22">
            descendant.token.min</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22descendant.token.sum.max%22">
            descendant.token.sum.max</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22descendant.token.sum.min%22">
            descendant.token.sum.min</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="DescendantToken_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="DescendantToken_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="FinalParameters">
      <subsection name="Description" id="FinalParameters_Description">
        <p>Since Checkstyle 3.0</p>
        <p>
          Check that parameters for methods, constructors, and catch blocks are
          final. Interface, abstract, and native methods are not checked: the final
          keyword does not make sense for interface, abstract, and native method
          parameters as there is no code that could modify the parameter.
        </p>

        <p>
          Rationale: Changing the value of parameters during the execution of
          the method's algorithm can be confusing and should be avoided. A
          great way to let the Java compiler prevent this coding style is to
          declare parameters final.
        </p>
      </subsection>

      <subsection name="Properties" id="FinalParameters_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>ignorePrimitiveTypes</td>
            <td>ignore primitive types as parameters</td>
            <td><a href="property_types.html#boolean">Boolean</a></td>
            <td><code>false</code></td>
            <td>6.2</td>
          </tr>
          <tr>
            <td>tokens</td>
            <td>tokens to check</td>
            <td>
              subset of tokens
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#METHOD_DEF">
                METHOD_DEF</a>,
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#CTOR_DEF">
                CTOR_DEF</a>,
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LITERAL_CATCH">
                LITERAL_CATCH</a>,
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#FOR_EACH_CLAUSE">
                FOR_EACH_CLAUSE</a>.
            </td>
            <td>
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#METHOD_DEF">
                METHOD_DEF</a>,
              <a href="apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#CTOR_DEF">
                CTOR_DEF</a>.
            </td>
            <td>3.0</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="FinalParameters_Examples">
        <p>
          To configure the check to enforce final parameters for methods and
          constructors:
        </p>
        <source>
&lt;module name=&quot;FinalParameters&quot;/&gt;
        </source>

        <p>
          To configure the check to enforce final parameters only for
          constructors:
        </p>
        <source>
&lt;module name=&quot;FinalParameters&quot;&gt;
  &lt;property name=&quot;tokens&quot; value=&quot;CTOR_DEF&quot;/&gt;
&lt;/module&gt;
        </source>
        <p>
          To configure the check to allow ignoring
          <a href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html">
           primitive datatypes</a> as parameters:
        </p>
        <source>
&lt;module name=&quot;FinalParameters&quot;&gt;
  &lt;property name=&quot;ignorePrimitiveTypes&quot; value=&quot;true&quot;/&gt;
&lt;/module&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="FinalParameters_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Asun_checks.xml+repo%3Acheckstyle%2Fcheckstyle+FinalParameters">
            Sun Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+FinalParameters">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="FinalParameters_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22final.parameter%22">
            final.parameter</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="FinalParameters_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="FinalParameters_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="Indentation">
      <subsection name="Description" id="Indentation_Description">
        <p>Since Checkstyle 3.1</p>
        <p>
          Checks correct indentation of Java code.
        </p>

        <p>
          The idea behind this is that while pretty printers are
          sometimes convenient for bulk reformats of legacy code, they often
          either aren't configurable enough or just can't anticipate how
          format should be done.  Sometimes this is personal preference, other
          times it is practical experience.  In any case, this check should
          just ensure that a minimal set of indentation rules is followed.
        </p>
      </subsection>

      <subsection name="Properties" id="Indentation_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>basicOffset</td>
            <td>how far new indentation level should be indented when on the next line</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>4</td>
            <td>3.1</td>
          </tr>
          <tr>
            <td>braceAdjustment</td>
            <td>how far a braces should be indented when on the next line</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>0</td>
            <td>3.1</td>
          </tr>
          <tr>
            <td>caseIndent</td>
            <td>how far a case label should be indented when on next line</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>4</td>
            <td>3.1</td>
          </tr>
          <tr>
            <td>throwsIndent</td>
            <td>how far a throws clause should be indented when on next line</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>4</td>
            <td>5.7</td>
          </tr>
          <tr>
            <td>arrayInitIndent</td>
            <td>how far an array initialisation should be indented when on next line</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>4</td>
            <td>5.8</td>
          </tr>
          <tr>
            <td>lineWrappingIndentation</td>
            <td>how far continuation line should be indented when line-wrapping is present</td>
            <td><a href="property_types.html#integer">Integer</a></td>
            <td>4</td>
            <td>5.9</td>
          </tr>
          <tr>
            <td>forceStrictCondition</td>
            <td>force strict indent level in line wrapping case. If value is true, line wrap indent
                have to be same as lineWrappingIndentation parameter. If value is false, line wrap
                indent could be bigger on any value user would like.</td>
            <td><a href="property_types.html#boolean">Boolean</a></td>
            <td>false</td>
            <td>6.3</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="Indentation_Examples">
        <p>
          To configure the check:
        </p>
        <source>
&lt;module name=&quot;Indentation&quot;/&gt;
        </source>

        <p>
          To configure the check to enforce the indentation style recommended by
          Oracle:
        </p>

        <source>
&lt;module name=&quot;Indentation&quot;&gt;
  &lt;property name=&quot;caseIndent&quot; value=&quot;0&quot;/&gt;
&lt;/module&gt;
        </source>
        <p>
          To configure the Check to enforce strict condition in line-wrapping validation.
        </p>
        <source>
&lt;module name=&quot;Indentation&quot;&gt;
  &lt;property name=&quot;forceStrictCondition&quot; value=&quot;true&quot;/&gt;
&lt;/module&gt;
        </source>
        <p>
          Such config doesn't allow next cases:
        </p>
        <source>
void foo(String aFooString,
        int aFooInt) {} // indent:8 ; expected: 4; warn, because 8 != 4
        </source>
        <p>
          But if forceStrictCondition = false, this code is valid:
        </p>
        <source>
void foo(String aFooString,
        int aFooInt) {} // indent:8 ; expected: > 4; ok, because 8 > 4
        </source>
      </subsection>

      <subsection name="Example of Usage" id="Indentation_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Agoogle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+Indentation">
            Google Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+Indentation">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="Indentation_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks%2Findentation+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22indentation.child.error%22">
            indentation.child.error</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks%2Findentation+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22indentation.child.error.multi%22">
            indentation.child.error.multi</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks%2Findentation+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22indentation.error%22">
            indentation.error</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks%2Findentation+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22indentation.error.multi%22">
            indentation.error.multi</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="Indentation_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks.indentation
        </p>
      </subsection>

      <subsection name="Parent Module" id="Indentation_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="NewlineAtEndOfFile">
      <subsection name="Description" id="NewlineAtEndOfFile_Description">
        <p>Since Checkstyle 3.1</p>
        <p>
          Checks whether files end with a line separator.
        </p>

        <p>
          Rationale: Any source files and text files in general should
          end with a line separator to let other easily add new content
          at the end of file and "diff" command does not show previous lines as changed.
          <br/>
          Example (line 36 should not be in diff):
          <img src="https://cloud.githubusercontent.com/assets/812984/13894408/afd965b8-ed24-11e5-8bfd-e9edf56a6fe6.png" alt="example of diff"/>
        </p>
        <p>
          Old Rationale: CVS source control management
          systems will even print a warning when it
          encounters a file that doesn't end with a line separator.
        </p>
        <p>
          Attention: property fileExtensions works with files that are passed by similar property
          for at <a href="config.html#Checker">Checker</a>.
          Please make sure required file extensions are mentioned at Checker's fileExtensions
          property.
        </p>
      </subsection>

      <subsection name="Properties" id="NewlineAtEndOfFile_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>lineSeparator</td>
            <td>type of line separator</td>
            <td><a href="property_types.html#lineSeparator">Line Separator Policy</a></td>
            <td>system</td>
            <td>3.1</td>
          </tr>
          <tr>
            <td>fileExtensions</td>
            <td>file type extension of the files to check.</td>
            <td><a href="property_types.html#stringSet">String Set</a></td>
            <td>all files</td>
            <td>3.1</td>
          </tr>

        </table>
      </subsection>

      <subsection name="Examples" id="NewlineAtEndOfFile_Examples">
        <p>
          To configure the check:
        </p>
        <source>
&lt;module name=&quot;NewlineAtEndOfFile&quot;/&gt;
        </source>

        <p>
          To configure the check to always use Unix-style line separators:
        </p>
        <source>
&lt;module name=&quot;NewlineAtEndOfFile&quot;&gt;
  &lt;property name=&quot;lineSeparator&quot; value=&quot;lf&quot;/&gt;
&lt;/module&gt;
        </source>

          <p>
            To configure the check to work only on Java, XML and Python files:
          </p>
          <source>
&lt;module name=&quot;NewlineAtEndOfFile&quot;&gt;
  &lt;property name=&quot;fileExtensions&quot; value=&quot;java, xml, py&quot;/&gt;
&lt;/module&gt;
          </source>
      </subsection>

      <subsection name="Example of Usage" id="NewlineAtEndOfFile_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Asun_checks.xml+repo%3Acheckstyle%2Fcheckstyle+NewlineAtEndOfFile">
            Sun Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+NewlineAtEndOfFile">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="NewlineAtEndOfFile_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22noNewlineAtEOF%22">
            noNewlineAtEOF</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22unable.open%22">
            unable.open</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="NewlineAtEndOfFile_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="NewlineAtEndOfFile_Parent_Module">
        <p>
          <a href="config.html#Checker">Checker</a>
        </p>
      </subsection>
    </section>

    <section name="OuterTypeFilename">
      <subsection name="Description" id="OuterTypeFilename_Description">
        <p>Since Checkstyle 5.3</p>
        <p>
          Checks that the outer type name and the file name match. For example,
          the class <code>Foo</code> must be in a file named
          <code>Foo.java</code>.
        </p>
      </subsection>

      <subsection name="Examples" id="OuterTypeFilename_Examples">
        <p>
          To configure the check:
        </p>
        <source>
&lt;module name=&quot;OuterTypeFilename&quot;/&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="OuterTypeFilename_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Agoogle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+OuterTypeFilename">
            Google Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+OuterTypeFilename">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="OuterTypeFilename_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22type.file.mismatch%22">
            type.file.mismatch</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="OuterTypeFilename_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="OuterTypeFilename_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="TodoComment">
      <subsection name="Description" id="TodoComment_Description">
        <p>Since Checkstyle 3.0</p>
        <p>
          A check for <code>TODO:</code> comments. Actually
          it is a generic <a
          href="https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">regular
          expression</a> matcher on Java comments. To check for other
          patterns in Java comments, set the <code>format</code> property.
        </p>
      </subsection>

      <subsection name="Properties" id="TodoComment_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>format</td>
            <td>Pattern to match comments against</td>
            <td><a href="property_types.html#regexp">Regular Expression</a></td>
            <td><code>"TODO:"</code></td>
            <td>3.0</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Notes" id="TodoComment_Notes">
        <p>
          Using <code>TODO:</code> comments is a great way
          to keep track of tasks that need to be done. Having them
          reported by Checkstyle makes it very hard to forget about
          them.
        </p>
      </subsection>

      <subsection name="Examples" id="TodoComment_Examples">
        <p>
          To configure the check:
        </p>
        <source>
&lt;module name=&quot;TodoComment&quot;/&gt;
        </source>

        <p>
          To configure the check for comments that contain <code>TODO</code> and <code>FIXME</code>:
        </p>
        <source>
&lt;module name=&quot;TodoComment&quot;&gt;
  &lt;property name=&quot;format&quot; value=&quot;(TODO)|(FIXME)&quot;/&gt;
&lt;/module&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="TodoComment_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Asun_checks.xml+repo%3Acheckstyle%2Fcheckstyle+TodoComment">
            Sun Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+TodoComment">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="TodoComment_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22todo.match%22">
            todo.match</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="TodoComment_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="TodoComment_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="TrailingComment">
      <subsection name="Description" id="TrailingComment_Description">
        <p>Since Checkstyle 3.4</p>
        <p>
          The check to ensure that requires that comments be the only thing on
          a line.  For the case of <code>//</code> comments that means that the only thing
          that should precede it is whitespace.  It doesn't check comments if
          they do not end a line; for example, it accepts the following:
          <code>Thread.sleep( 10 &lt;some comment here&gt; );</code> Format
          property is intended to deal with the "} // while" example.
        </p>

        <p>
          Rationale: Steve McConnell in <cite>Code Complete</cite> suggests that
          endline comments are a bad practice. An end line comment would be
          one that is on the same line as actual code. For example:
        </p>

        <source>
a = b + c;      // Some insightful comment
d = e / f;        // Another comment for this line
        </source>

        <p>
          Quoting <cite>Code Complete</cite> for the justification:
        </p>

        <ul>
          <li> &quot;The comments have to be aligned so that they do not
          interfere with the visual structure of the code. If you don't align
          them neatly, they'll make your listing look like it's been through a
          washing machine.&quot;
          </li>
          <li> &quot;Endline comments tend to be hard to format...It takes
          time to align them. Such time is not spent learning more about the
          code; it's dedicated solely to the tedious task of pressing the
          spacebar or tab key.&quot;
          </li>
          <li> &quot;Endline comments are also hard to maintain. If the code
          on any line containing an endline comment grows, it bumps the
          comment farther out, and all the other endline comments will have to
          bumped out to match. Styles that are hard to maintain aren't
          maintained....&quot;
          </li>
          <li> &quot;Endline comments also tend to be cryptic. The right side
          of the line doesn't offer much room and the desire to keep the
          comment on one line means the comment must be short.  Work then goes
          into making the line as short as possible instead of as clear as
          possible. The comment usually ends up as cryptic as
          possible....&quot;
          </li>
          <li> &quot;A systemic problem with endline comments is that it's
          hard to write a meaningful comment for one line of code. Most
          endline comments just repeat the line of code, which hurts more than
          it helps.&quot;
          </li>
        </ul>

        <p>
          McConnell's comments on being hard to maintain when the size of the line
          changes are even more important in the age of automated
          refactorings.
        </p>
      </subsection>

      <subsection name="Properties" id="TrailingComment_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>format</td>
            <td>pattern for strings allowed before the comment</td>
            <td><a href="property_types.html#regexp">Regular Expression</a></td>
            <td><code>"^[\s});]*$"</code></td>
            <td>3.4</td>
          </tr>
          <tr>
            <td>legalComment</td>
            <td>pattern for text allowed in trailing comments. (This
                pattern will not be applied to multiline comments and the text of the
                comment will be trimmed before matching.)</td>
            <td><a href="property_types.html#regexp">Regular Expression</a></td>
            <td><code>null</code></td>
            <td>4.2</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="TrailingComment_Examples">
        <p>
          To configure the check:
        </p>
        <source>
&lt;module name=&quot;TrailingComment&quot;/&gt;
        </source>

        <p>
          To configure the check so it enforces only comment on a line:
        </p>
        <source>
&lt;module name=&quot;TrailingComment&quot;&gt;
  &lt;property name=&quot;format&quot; value=&quot;^\\s*$&quot;/&gt;
&lt;/module&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="TrailingComment_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+TrailingComment">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="TrailingComment_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22trailing.comments%22">
            trailing.comments</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="TrailingComment_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="TrailingComment_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="Translation">
      <subsection name="Description" id="Translation_Description">
        <p>Since Checkstyle 3.0</p>
        <p>
          A <a href="config.html#Overview">FileSetCheck</a> that ensures
          the correct translation of code by checking property files for
          consistency regarding their keys. Two property files
          describing one and the same context are consistent if they
          contain the same keys. TranslationCheck also can check an existence of required
          translations which must exist in project, if 'requiredTranslations' option is used.
        </p>

        <p>
          Consider the following properties file in the same directory:
        </p>
        <source>
#messages.properties
hello=Hello
cancel=Cancel

#messages_de.properties
hell=Hallo
ok=OK
        </source>

        <p>
          The Translation check will find the typo in the German <code>hello</code>
          key, the missing <code>ok</code> key in the default resource file and the
          missing <code>cancel</code> key in the German resource file:
        </p>
        <source>
messages_de.properties: Key 'hello' missing.
messages_de.properties: Key 'cancel' missing.
messages.properties: Key 'hell' missing.
messages.properties: Key 'ok' missing.
        </source>
        <p>
          <font color="red">Attention:</font> this Check could produce false-positives if it
          is used with <a href="config.html#Checker">Checker</a> that use cache (property
          "cacheFile") This is known design problem, will be addressed at
          <a href="https://github.com/checkstyle/checkstyle/issues/3539">issue</a>.
        </p>
      </subsection>

      <subsection name="Properties" id="Translation_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>fileExtensions</td>
            <td>
              File type extension to identify translation files. Setting
              this property is typically only required if your
              translation files are preprocessed and the original files
              do not have the extension <code>.properties</code>
            </td>
            <td><a href="property_types.html#stringSet">String Set</a></td>
            <td><code>.properties</code></td>
            <td>3.0</td>
          </tr>
          <tr>
            <td>baseName</td>
            <td><a href="https://docs.oracle.com/javase/7/docs/api/java/util/ResourceBundle.html">
              Base name</a> of resource bundles which contain message resources. It helps
              the check to distinguish config and localization resources.</td>
            <td><a href="property_types.html#regexp">Regular Expression</a></td>
            <td><code>"^messages.*$"</code></td>
            <td>6.17</td>
          </tr>
          <tr>
            <td>requiredTranslations</td>
            <td>
              Allows to specify language codes of required translations which must exist in project.
              Language code is composed of the lowercase, two-letter codes as defined by
              <a href="https://en.wikipedia.org/wiki/List_of_ISO_639-1_codes">ISO 639-1</a>.
              Default value is empty String Set which means that only the existence
              of default translation is checked. Note, if you specify language codes (or just
              one language code) of required translations the check will also check for
              existence of default translation files in project.
              ATTENTION: the check will perform the validation of ISO codes if the option
              is used. So, if you specify, for example, "mm" for language code, TranslationCheck
              will rise violation that the language code is incorrect.
            </td>
            <td><a href="property_types.html#stringSet">String Set</a></td>
            <td><code>{}</code></td>
            <td>6.11</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="Translation_Examples">
        <p>
          To configure the check to check only files which have '.properties' and '.translations'
          extensions:
        </p>
        <source>
&lt;module name=&quot;Translation&quot;&gt;
  &lt;property name=&quot;fileExtensions&quot; value=&quot;properties, translations&quot;/&gt;
&lt;/module&gt;
        </source>
        <p>
          Note, that files with the same path and base name but which have different
          extensions will be considered as files that belong to different resource bundles.
        </p>
        <p>
          An example of how to configure the check to validate only bundles which base names
          start with "ButtonLabels":
        </p>
        <source>
&lt;module name=&quot;Translation&quot;&gt;
  &lt;property name=&quot;baseName&quot; value=&quot;^ButtonLabels.*$&quot;/&gt;
&lt;/module&gt;
        </source>

        <p>
          To configure the check to check existence of Japanese and French translations:
        </p>
        <source>
&lt;module name=&quot;Translation&quot;&gt;
  &lt;property name=&quot;requiredTranslations&quot; value=&quot;ja, fr&quot;/&gt;
&lt;/module&gt;
        </source>
        <p>
          The following example shows how the check works if there is a message bundle which
          element name contains language code, county code, platform name.
          Consider that we have the below configuration:
        </p>
        <source>
&lt;module name=&quot;Translation&quot;&gt;
  &lt;property name=&quot;requiredTranslations&quot; value=&quot;es, fr, de&quot;/&gt;
&lt;/module&gt;
        </source>
        <p>
        </p>
        <p>
          As we can see from the configuration, the TranslationCheck was configured to check
          an existence of 'es', 'fr' and 'de' translations. Lets assume that we have the resource
          bundle:
        </p>
        <source>
messages_home.properties
messages_home_es_US.properties
messages_home_fr_CA_UNIX.properties
        </source>
        <p>
          Than the check will rise the following violation:
          "0: Properties file 'messages_home_de.properties' is missing."
        </p>
      </subsection>

      <subsection name="Example of Usage" id="Translation_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Asun_checks.xml+repo%3Acheckstyle%2Fcheckstyle+Translation">
            Sun Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+Translation">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="Translation_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22translation.missingKey%22">
            translation.missingKey</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22translation.missingTranslationFile%22">
            translation.missingTranslationFile</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="Translation_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="Translation_Parent_Module">
        <p>
          <a href="config.html#Checker">Checker</a>
        </p>
      </subsection>
    </section>

    <section name="UncommentedMain">
      <subsection name="Description" id="UncommentedMain_Description">
        <p>Since Checkstyle 3.2</p>
        <p>
          Checks for uncommented main() methods.
        </p>

        <p>
          Rationale: A main() method is often used for debugging
          purposes. When debugging is finished, developers often forget
          to remove the method, which changes the API and increases the
          size of the resulting class or JAR file. With the exception of
          the real program entry points, all main() methods should be
          removed or commented out of the sources.
        </p>
      </subsection>

      <subsection name="Properties" id="UncommentedMain_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>excludedClasses</td>
            <td>Pattern for qualified names of classes which are allowed
            to have a main method.</td>
            <td><a href="property_types.html#regexp">Regular Expression</a></td>
            <td><code>"^$" (empty)</code></td>
            <td>3.2</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="UncommentedMain_Examples">
        <p>
          To configure the check:
        </p>
        <source>
&lt;module name=&quot;UncommentedMain&quot;/&gt;
        </source>

        <p>
          To configure the check to allow the <code>main</code> method for all classes
          with &quot;Main&quot; name:
        </p>
        <source>
&lt;module name=&quot;UncommentedMain&quot;&gt;
  &lt;property name=&quot;excludedClasses&quot; value=&quot;\.Main$&quot;/&gt;
&lt;/module&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="UncommentedMain_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+UncommentedMain">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="UncommentedMain_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22uncommented.main%22">
            uncommented.main</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="UncommentedMain_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="UncommentedMain_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>

    <section name="UniqueProperties">
      <subsection name="Description" id="UniqueProperties_Description">
        <p>Since Checkstyle 5.7</p>
        <p>
          Checks properties files for duplicated properties.
        </p>
        <p>
          Rationale: Multiple property keys usually appear after merge
          or rebase of several branches. While there are no errors in
          runtime, there can be a confusion due to having different values
          for the duplicated properties.
        </p>

      </subsection>

      <subsection name="Properties" id="UniqueProperties_Properties">
        <table>
          <tr>
            <th>name</th>
            <th>description</th>
            <th>type</th>
            <th>default value</th>
            <th>since</th>
          </tr>
          <tr>
            <td>fileExtensions</td>
            <td>file type extension of the files to check.</td>
            <td><a href="property_types.html#stringSet">String Set</a></td>
            <td>.properties</td>
            <td>5.7</td>
          </tr>
        </table>
      </subsection>

      <subsection name="Examples" id="UniqueProperties_Examples">
        <p>
          To configure the check:
        </p>
        <source>
&lt;module name=&quot;UniqueProperties&quot;&gt;
  &lt;property name=&quot;fileExtensions&quot; value=&quot;properties&quot; /&gt;
&lt;/module&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="UniqueProperties_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+UniqueProperties">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="UniqueProperties_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22properties.duplicate.property%22">
            properties.duplicate.property</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22unable.open.cause%22">
            unable.open.cause</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="UniqueProperties_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="UniqueProperties_Parent_Module">
        <p>
          <a href="config.html#Checker">Checker</a>
        </p>
      </subsection>
    </section>

    <section name="UpperEll">
      <subsection name="Description" id="UpperEll_Description">
        <p>Since Checkstyle 3.0</p>
        <p>
          Checks that long constants are defined with an upper ell. That
          is <code>' L'</code> and not <code>'l'</code>. This is in accordance with the Java
          Language Specification, <a
          href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.1">
          Section 3.10.1</a>.
        </p>

        <p>
          The lower-case ell <code>'l'</code> looks a lot like <code>1</code>.
        </p>
      </subsection>

      <subsection name="Examples" id="UpperEll_Examples">
        <p>
          To configure the check:
        </p>
        <source>
&lt;module name=&quot;UpperEll&quot;/&gt;
        </source>
      </subsection>

      <subsection name="Example of Usage" id="UpperEll_Example_of_Usage">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Agoogle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+UpperEll">
            Google Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources+filename%3Asun_checks.xml+repo%3Acheckstyle%2Fcheckstyle+UpperEll">
            Sun Style</a>
          </li>
          <li>
            <a href="https://github.com/search?q=path%3Aconfig+filename%3Acheckstyle_checks.xml+repo%3Acheckstyle%2Fcheckstyle+UpperEll">
            Checkstyle Style</a>
          </li>
        </ul>
      </subsection>

      <subsection name="Error Messages" id="UpperEll_Error_Messages">
        <ul>
          <li>
            <a href="https://github.com/search?q=path%3Asrc%2Fmain%2Fresources%2Fcom%2Fpuppycrawl%2Ftools%2Fcheckstyle%2Fchecks+filename%3Amessages*.properties+repo%3Acheckstyle%2Fcheckstyle+%22upperEll%22">
            upperEll</a>
          </li>
        </ul>
        <p>
          All messages can be customized if the default message doesn't suit you.
          Please <a href="config.html#Custom_messages">see the documentation</a> to learn how to.
        </p>
      </subsection>

      <subsection name="Package" id="UpperEll_Package">
        <p>
          com.puppycrawl.tools.checkstyle.checks
        </p>
      </subsection>

      <subsection name="Parent Module" id="UpperEll_Parent_Module">
        <p>
          <a href="config.html#TreeWalker">TreeWalker</a>
        </p>
      </subsection>
    </section>
  </body>
</document>