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Checkstyle is a development tool to help programmers write Java code that adheres to a coding standard

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<?xml version="1.0" encoding="UTF-8"?>
<checkstyle-metadata>
   <module>
      <check fully-qualified-name="com.puppycrawl.tools.checkstyle.checks.coding.ArrayTrailingCommaCheck"
             name="ArrayTrailingComma"
             parent="com.puppycrawl.tools.checkstyle.TreeWalker">
         <description>&lt;p&gt;
 Checks that array initialization contains a trailing comma.
 &lt;/p&gt;
 &lt;pre&gt;
 int[] a = new int[]
 {
   1,
   2,
   3,
 };
 &lt;/pre&gt;
 &lt;p&gt;
 By default, the check demands a comma at the end if neither left nor right curly braces
 are on the same line as the last element of the array.
 &lt;/p&gt;
 &lt;pre&gt;
 return new int[] { 0 };
 return new int[] { 0
   };
 return new int[] {
   0 };
 &lt;/pre&gt;
 &lt;p&gt;
 Rationale: Putting this comma in makes it easier to change the
 order of the elements or add new elements on the end. Main benefit of a trailing
 comma is that when you add new entry to an array, no surrounding lines are changed.
 &lt;/p&gt;
 &lt;pre&gt;
 {
   100000000000000000000,
   200000000000000000000, // OK
 }

 {
   100000000000000000000,
   200000000000000000000,
   300000000000000000000,  // Just this line added, no other changes
 }
 &lt;/pre&gt;
 &lt;p&gt;
 If closing brace is on the same line as trailing comma, this benefit is gone
 (as the check does not demand a certain location of curly braces the following
 two cases will not produce a violation):
 &lt;/p&gt;
 &lt;pre&gt;
 {100000000000000000000,
  200000000000000000000,} // Trailing comma not needed, line needs to be modified anyway

 {100000000000000000000,
  200000000000000000000, // Modified line
  300000000000000000000,} // Added line
 &lt;/pre&gt;
 &lt;p&gt;
 If opening brace is on the same line as trailing comma there's also (more arguable) problem:
 &lt;/p&gt;
 &lt;pre&gt;
 {100000000000000000000, // Line cannot be just duplicated to slightly modify entry
 }

 {100000000000000000000,
  100000000000000000001, // More work needed to duplicate
 }
 &lt;/pre&gt;</description>
         <properties>
            <property default-value="false"
                      name="alwaysDemandTrailingComma"
                      type="boolean">
               <description>Control whether to always check for a trailing
 comma, even when an array is inline.</description>
            </property>
         </properties>
         <message-keys>
            <message-key key="array.trailing.comma"/>
         </message-keys>
      </check>
   </module>
</checkstyle-metadata>