 ------
 Using Rule Sets
 ------
 Maria Odea Ching
 ------
 2018-01-10
 ------

 ~~ Licensed to the Apache Software Foundation (ASF) under one
 ~~ or more contributor license agreements.  See the NOTICE file
 ~~ distributed with this work for additional information
 ~~ regarding copyright ownership.  The ASF licenses this file
 ~~ to you under the Apache License, Version 2.0 (the
 ~~ "License"); you may not use this file except in compliance
 ~~ with the License.  You may obtain a copy of the License at
 ~~
 ~~   http://www.apache.org/licenses/LICENSE-2.0
 ~~
 ~~ Unless required by applicable law or agreed to in writing,
 ~~ software distributed under the License is distributed on an
 ~~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 ~~ KIND, either express or implied.  See the License for the
 ~~ specific language governing permissions and limitations
 ~~ under the License.

~~ NOTE: For help with the syntax of this file, see:
~~ http://maven.apache.org/doxia/references/apt-format.html

Using Rule Sets

 The PMD plugin ships a default rule set, that has various rules enabled. The ruleset is available
 as </rulesets/java/maven-pmd-plugin-default.xml>. See below for the rules, that are enabled with
 the default rule set.
 
 There are many more rules available and bundled in the PMD code analysis tool:

  * {{{https://pmd.github.io/pmd-${pmdVersion}/pmd_rules_java.html}Java Rule Index}}

  * {{{https://pmd.github.io/pmd-${pmdVersion}/pmd_rules_ecmascript.html}JavaScript Rule Index}}

  * {{{https://pmd.github.io/pmd-${pmdVersion}/pmd_rules_jsp.html}JSP Rule Index}}

 To use other rule sets, you can configure it in the plugin as shown below.
 The rule sets may reside in the classpath, filesystem or at a URL. For rule sets that are bundled
 with the PMD tool, you do not need to specificy the absolute path of the file. It will be resolved by
 the plugin. But if the rule set is a custom rule set, you need to specify its absolute path.
 
 See {{{https://pmd.github.io/pmd-${pmdVersion}/pmd_userdocs_making_rulesets.html}Making Rulesets}}
 if you want to create your own custom ruleset.

 <<Note:>> Starting with PMD 5.0 and Maven PMD Plugin 3.0 the paths to the
 bundled rule sets for the Java language were changed from
 <<</rulesets/xyz.xml>>> to <<</rulesets/java/xyz.xml>>>. So when upgrading to
 Maven PMD Plugin 3.0 you may need to alter your plugin configuration.
 
 <<Note:>> Starting with PMD 6.0.0 and Maven PMD Plugin 3.9.0, the rules have been reorganized
 into categories, e.g. <<</category/java/bestpractices.xml>>>. So when upgrading to
 Maven PMD Plugin 3.9.0 you should review your plugin configuration and/or custom ruleset.

+-----+
<project>
  ...
  <reporting>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-pmd-plugin</artifactId>
        <version>${project.version}</version>
        <configuration>
          <rulesets>
            <!-- A rule set, that comes bundled with PMD -->
            <ruleset>/category/java/bestpractices.xml</ruleset>
            <!-- Custom local file system rule set -->
            <ruleset>d:\rulesets\strings.xml</ruleset>
            <!-- Custom remote rule set accessed via a URL -->
            <ruleset>http://localhost/design.xml</ruleset>
          </rulesets>
        </configuration>
      </plugin>
    </plugins>
  </reporting>
  ...
</project>
+-----+


The default ruleset

  This is an excerpt of the ruleset <<</rulesets/java/maven-pmd-plugin-default.xml>>>.
  It contains only rules for Java.
  If you use a different language, you'll need to specify your own custom ruleset.

  The current version of the ruleset can be found in version control:
  {{https://gitbox.apache.org/repos/asf?p=maven-pmd-plugin.git;a=blob_plain;f=src/main/resources/rulesets/java/maven-pmd-plugin-default.xml;hb=HEAD}}

+-----+
    <rule ref="category/java/bestpractices.xml/AvoidUsingHardCodedIP" />
    <rule ref="category/java/bestpractices.xml/CheckResultSet" />
    <rule ref="category/java/bestpractices.xml/UnusedImports" />
    <rule ref="category/java/bestpractices.xml/UnusedFormalParameter" />
    <rule ref="category/java/bestpractices.xml/UnusedLocalVariable" />
    <rule ref="category/java/bestpractices.xml/UnusedPrivateField" />
    <rule ref="category/java/bestpractices.xml/UnusedPrivateMethod" />

    <rule ref="category/java/codestyle.xml/DontImportJavaLang" />
    <rule ref="category/java/codestyle.xml/DuplicateImports" />
    <rule ref="category/java/codestyle.xml/ExtendsObject" />
    <rule ref="category/java/codestyle.xml/ForLoopShouldBeWhileLoop" />
    <rule ref="category/java/codestyle.xml/TooManyStaticImports" />
    <rule ref="category/java/codestyle.xml/UnnecessaryFullyQualifiedName" />
    <rule ref="category/java/codestyle.xml/UnnecessaryModifier" />
    <rule ref="category/java/codestyle.xml/UnnecessaryReturn" />
    <rule ref="category/java/codestyle.xml/UselessParentheses" />
    <rule ref="category/java/codestyle.xml/UselessQualifiedThis" />

    <rule ref="category/java/design.xml/CollapsibleIfStatements" />
    <rule ref="category/java/design.xml/SimplifiedTernary" />
    <rule ref="category/java/design.xml/UselessOverridingMethod" />

    <rule ref="category/java/errorprone.xml/AvoidBranchingStatementAsLastInLoop" />
    <rule ref="category/java/errorprone.xml/AvoidDecimalLiteralsInBigDecimalConstructor" />
    <rule ref="category/java/errorprone.xml/AvoidMultipleUnaryOperators" />
    <rule ref="category/java/errorprone.xml/AvoidUsingOctalValues" />
    <rule ref="category/java/errorprone.xml/BrokenNullCheck" />
    <rule ref="category/java/errorprone.xml/CheckSkipResult" />
    <rule ref="category/java/errorprone.xml/ClassCastExceptionWithToArray" />
    <rule ref="category/java/errorprone.xml/DontUseFloatTypeForLoopIndices" />
    <rule ref="category/java/errorprone.xml/EmptyCatchBlock" />
    <rule ref="category/java/errorprone.xml/EmptyFinallyBlock" />
    <rule ref="category/java/errorprone.xml/EmptyIfStmt" />
    <rule ref="category/java/errorprone.xml/EmptyInitializer" />
    <rule ref="category/java/errorprone.xml/EmptyStatementBlock" />
    <rule ref="category/java/errorprone.xml/EmptyStatementNotInLoop" />
    <rule ref="category/java/errorprone.xml/EmptySwitchStatements" />
    <rule ref="category/java/errorprone.xml/EmptySynchronizedBlock" />
    <rule ref="category/java/errorprone.xml/EmptyTryBlock" />
    <rule ref="category/java/errorprone.xml/EmptyWhileStmt" />
    <rule ref="category/java/errorprone.xml/ImportFromSamePackage" />
    <rule ref="category/java/errorprone.xml/JumbledIncrementer" />
    <rule ref="category/java/errorprone.xml/MisplacedNullCheck" />
    <rule ref="category/java/errorprone.xml/OverrideBothEqualsAndHashcode" />
    <rule ref="category/java/errorprone.xml/ReturnFromFinallyBlock" />
    <rule ref="category/java/errorprone.xml/UnconditionalIfStatement" />
    <rule ref="category/java/errorprone.xml/UnnecessaryConversionTemporary" />
    <rule ref="category/java/errorprone.xml/UnusedNullCheckInEquals" />
    <rule ref="category/java/errorprone.xml/UselessOperationOnImmutable" />

    <rule ref="category/java/multithreading.xml/AvoidThreadGroup" />
    <rule ref="category/java/multithreading.xml/DontCallThreadRun" />
    <rule ref="category/java/multithreading.xml/DoubleCheckedLocking" />

    <rule ref="category/java/performance.xml/BigIntegerInstantiation" />
    <rule ref="category/java/performance.xml/BooleanInstantiation" />
+-----+