Merge pull request #3720 from

vgalloy:FinalInterfaceMethodParameterIsUnclear

[java] New rule: FinalParameterInAbstractMethod #3720

* pr-3720:
  [doc] Update release notes (#3720)
  Fix file name
  Fix test class name
  Fix FinalParameterInAbstractMethod.externalInfoUrl
  Rename to FinalParameterInAbstractMethod and target all methods
  [java] New rule: FinalInterfaceMethodParameterIsUnclear

docs/pages/release_notes.md

@@ -14,6 +14,18 @@ This is a {{ site.pmd.release_type }} release.
 
 ### New and noteworthy
 
+#### New rules
+
+*   The new Java rule {% rule "java/codestyle/FinalParameterInAbstractMethod" %} detects parameters that are
+    declared as final in interfaces or abstract methods. Declaring the parameters as final is useless
+    because the implementation may choose to not respect it.
+
+```xml
+    <rule ref="category/java/codestyle.xml/FinalParameterInAbstractMethod" />
+```
+
+   The rule is part of the quickstart.xml ruleset.
+
 #### Modified rules
 
 *   The Apex rule {% rule "apex/documentation/ApexDoc" %} has a new property `reportProperty`.
@@ -43,6 +55,7 @@ This is a {{ site.pmd.release_type }} release.
 *   [#3704](https://github.com/pmd/pmd/pull/3704): \[java] Fix for #3686 - Fix ReturnEmptyCollectionRatherThanNull - [Oleksii Dykov](https://github.com/dykov)
 *   [#3713](https://github.com/pmd/pmd/pull/3713): \[java] Enhance UnnecessaryModifier to support records - [Vincent Galloy](https://github.com/vgalloy)
 *   [#3719](https://github.com/pmd/pmd/pull/3719): \[java] Upgrade log4j to 2.17.1 - [Daniel Paul Searles](https://github.com/squaresurf)
+*   [#3720](https://github.com/pmd/pmd/pull/3720): \[java] New rule: FinalParameterInAbstractMethod - [Vincent Galloy](https://github.com/vgalloy)
 *   [#3724](https://github.com/pmd/pmd/pull/3724): \[java] Fix for #3686 - fix FinalFieldCouldBeStatic - [Oleksii Dykov](https://github.com/dykov)
 
 {% endtocmaker %}

pmd-core/src/main/resources/rulesets/releases/6420.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+
+<ruleset name="6420"
+    xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd">
+  <description>
+This ruleset contains links to rules that are new in PMD v6.42.0
+  </description>
+
+    <rule ref="category/java/codestyle.xml/FinalParameterInAbstractMethod" />
+
+</ruleset>

pmd-java/src/main/resources/category/java/bestpractices.xml

@@ -541,7 +541,6 @@ return a;
         </example>
     </rule>
 
-
     <rule name="ForLoopCanBeForeach"
           language="java"
           since="6.0.0"

pmd-java/src/main/resources/category/java/codestyle.xml

@@ -802,6 +802,39 @@ public class HelloWorldBean {
         </example>
     </rule>
 
+    <rule name="FinalParameterInAbstractMethod"
+          language="java"
+          since="6.42.0"
+          message="Final parameter in abstract method"
+          class="net.sourceforge.pmd.lang.rule.XPathRule"
+          typeResolution="true"
+          externalInfoUrl="${pmd.website.baseurl}/pmd_rules_java_codestyle.html#finalparameterinabstractmethod">
+        <description>
+            Declaring a method parameter as final for an interface method is useless because the implementation may choose to not respect it.
+        </description>
+        <priority>1</priority>
+        <properties>
+            <property name="version" value="2.0"/>
+            <property name="xpath">
+                <value>
+                    <![CDATA[
+//MethodDeclaration[
+    MethodDeclarator/FormalParameters/FormalParameter[@Final = true()] and
+    not(Block)
+]
+]]>
+                </value>
+            </property>
+        </properties>
+        <example>
+            <![CDATA[
+public interface MyInterface {
+  void process(final Object arg); // Avoid using final here
+}
+]]>
+        </example>
+    </rule>
+
     <rule name="ForLoopShouldBeWhileLoop"
           language="java"
           since="1.02"

pmd-java/src/main/resources/rulesets/java/quickstart.xml

@@ -93,6 +93,7 @@
     <!-- <rule ref="category/java/codestyle.xml/EmptyMethodInAbstractClassShouldBeAbstract" /> -->
     <rule ref="category/java/codestyle.xml/ExtendsObject"/>
     <!-- <rule ref="category/java/codestyle.xml/FieldDeclarationsShouldBeAtStartOfClass" /> -->
+    <rule ref="category/java/codestyle.xml/FinalParameterInAbstractMethod"/>
     <rule ref="category/java/codestyle.xml/ForLoopShouldBeWhileLoop"/>
     <rule ref="category/java/codestyle.xml/IdenticalCatchBranches"/>
     <!-- <rule ref="category/java/codestyle.xml/LocalVariableCouldBeFinal" /> -->

pmd-java/src/test/java/net/sourceforge/pmd/lang/java/rule/codestyle/FinalParameterInAbstractMethodTest.java

@@ -0,0 +1,11 @@
+/*
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.lang.java.rule.codestyle;
+
+import net.sourceforge.pmd.testframework.PmdRuleTst;
+
+public class FinalParameterInAbstractMethodTest extends PmdRuleTst {
+    // no additional unit tests
+}

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/codestyle/xml/FinalParameterInAbstractMethod.xml

@@ -0,0 +1,75 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<test-data
+        xmlns="http://pmd.sourceforge.net/rule-tests"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="http://pmd.sourceforge.net/rule-tests http://pmd.sourceforge.net/rule-tests_1_0_0.xsd">
+
+    <test-code>
+        <description>Final is not allowed in interface public method</description>
+        <expected-problems>1</expected-problems>
+        <expected-messages>
+            <message>Final parameter in abstract method</message>
+        </expected-messages>
+        <code><![CDATA[
+public interface Foo {
+    void bar(final int a);
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Final is allowed in interface static method</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public interface Foo {
+    static void bar(final int a) {}
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Final is allowed in interface private method</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public interface Foo {
+    private void bar(final int a) {}
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Final is allowed in interface default method</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public interface Foo {
+    default void bar(final int a) {}
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Final is allowed in interface inner class method</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public interface Foo {
+  class Inner {
+    public void bar(final int a) {}
+  }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Final is not allowed in abstract method</description>
+        <expected-problems>1</expected-problems>
+        <expected-messages>
+            <message>Final parameter in abstract method</message>
+        </expected-messages>
+        <code><![CDATA[
+public abstract class Foo {
+    abstract void bar(final int a);
+}
+        ]]></code>
+    </test-code>
+
+</test-data>