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

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>