Merge branch 'master' into uselessoverridingmethod-false-negative

.travis/pmd-code-api.sh

@@ -48,7 +48,7 @@ function pmd_code_uploadJavadoc() {
 
     log_debug "$FUNCNAME pmdVersion=$pmdVersion basePath=$basePath"
 
-    for i in ${basePath}/*/target/*-javadoc.jar; do
+    for i in ${basePath}/*/target/*-javadoc.jar */*/target/*-javadoc.jar; do
         pmd_code_uploadJavadocModule "$pmdVersion" "$i"
     done
 

do-release.sh

@@ -88,7 +88,7 @@ echo "*   Update **pmd-apex/src/main/resources/rulesets/apex/quickstart.xml** an
 echo "    **pmd-java/src/main/resources/rulesets/java/quickstart.xml** with the new rules."
 echo
 echo "*   Update **docs/pages/next_major_development.md** with the API changes for"
-echo "    the new release based on the release notes"
+echo "    the new release based on the release notes. Also add any deprecated rules to the list."
 echo
 echo "*   Update **../pmd.github.io/_config.yml** to mention the new release"
 echo

docs/_plugins/javadoc_tag.rb

@@ -226,6 +226,11 @@ class JavadocTag < Liquid::Tag
   def self.fqcn_type(artifact_id, fqcn)
 
     artifact_dir = File.join(BASE_PMD_DIR, artifact_id)
+    # special case for scala as we have a different directory structure there
+    if artifact_id =~ /scala/
+      artifact_dir = File.join(BASE_PMD_DIR, "pmd-scala-modules/pmd-scala-common")
+    end
+
     src_dirs = [
         File.join(artifact_dir, "src", "main", "java"),
         File.join(artifact_dir, "target", "generated-sources", "javacc")

docs/_plugins/jdoc_namespace_tag.rb

@@ -86,9 +86,14 @@ class JDocNamespaceDeclaration < Liquid::Tag
       expanded_fqcn += "." + fqcn_suffix
     end
 
+    artifactId = resolved_nspace.first
+
+    if artifactId =~ /scala/
+      artifactId = "pmd-scala_2.13"
+    end
 
     # Return the resolved artifactId + the expanded FQCN
-    [resolved_nspace.first, expanded_fqcn]
+    [artifactId, expanded_fqcn]
   end
 
   private

docs/pages/next_major_development.md

@@ -4,17 +4,69 @@ permalink: pmd_next_major_development.html
 keywords: changelog, release notes, deprecation, api changes
 ---
 
-We're excited to bring you the next major version of PMD! Here are the major features and changes we're working on.
+We're excited to bring you the next major version of PMD!
+Here is a summary of what is planned for PMD 7.
+
 To give us feedback or to suggest a new feature, drop us a line on [Gitter](https://gitter.im/pmd/pmd)!
 
-## New Features
+## Summary
 
-TODO
+### New Logo
 
-## Java grammar changes
+We decided it's time to have a modernized logo and get rid of the gun. This allows to include
+the logo in anywhere without offense.
 
-{% include note.html content="Current plans are listed [here](https://github.com/pmd/pmd/labels/in%3Aast) and in particular [here](https://github.com/pmd/pmd/issues/1019)" %}
+The current tasks are listed here: [Integrate new PMD logo #1931](https://github.com/pmd/pmd/issues/1931)
 
+### API
+
+The API of PMD has been growing over the years and needs to be cleaned up. The goal is, to
+have a clear separation between a well-defined API and the implementation, which is internal.
+This should help us in future development. This however entails some incompatibilities and
+deprecations, see also the sections [New API support guidelines](#new-api-support-guidelines) and
+[Planned API removals](#planned-api-removals] below.
+
+### Full Antlr Support
+
+PMD 6 only supports JavaCC based grammars, but with [Antlr](https://www.antlr.org/) parsers
+can be generated as well. PMD 7 adds full support for grammars written in Antlr, which allows
+to leverage existing grammars.
+
+The current tasks are listed here: [Support for ANTLR based grammars with Swift as an example language #2499](https://github.com/pmd/pmd/issues/2499)
+
+### Documentation
+
+We have quite some ideas how we want to improve the documentation. The goal is, that the documentation is
+up to date and nearly complete. One big task is, how the built-in rules are presented, so that users
+can easier see, what exactly is available and decide, which rules are useful for the project at hand.
+
+The current tasks are listed here: [Documentations improvements tracker #1139](https://github.com/pmd/pmd/issues/1139)
+
+### XPath
+
+PMD 6 supports XPath 1.0 via the Jaxen library. This library is old and unmaintained creating some problems
+(one of which is duplicated classes in the package `org.w3c.dom` which is a Java API actually).
+Therefore XPath 1.0 support will be dropped and we upgrade our XPath 2.0 implementation with Saxon moving
+on to Saxon HE. This will eventually add support in PMD for XPath 3.1.
+
+The current tasks are listed here: [XPath Improvements for PMD 7 #2523](https://github.com/pmd/pmd/issues/2523)
+
+### Java
+
+Like the main PMD API, the Java AST has been growing over time and the grammar doesn't support
+all edge cases (e.g. annotation are not supported everywhere). The goal is to simplify the AST by reducing
+unnecessary nodes and abstractions and fix the parsing issues.
+This helps in the end to provide a better type resolution implementation, but changing the AST is a breaking
+API change.
+
+Some first results of the Java AST changes are for now documented in the Wiki:
+[Java clean changes](https://github.com/pmd/pmd/wiki/Java_clean_changes).
+
+### Miscellaneous
+
+There are also some small improvements, refactoring and internal tasks that are planned for PMD 7.
+
+The current tasks are listed here: [PMD 7 Miscellaneous Tasks #2524](https://github.com/pmd/pmd/issues/2524)
 
 
 ## New API support guidelines
@@ -878,14 +930,18 @@ large projects, with many duplications, it was causing `OutOfMemoryError`s (see
     and {% rule "java/bestpractices/PositionLiteralsFirstInCaseInsensitiveComparisons" %} (ruleset `java-bestpractices`)
     have been deprecated in favor of the new rule {% rule "java/bestpractices/LiteralsFirstInComparisons" %}.
 
+*   The Java rule [`AvoidFinalLocalVariable`](https://pmd.github.io/pmd-6.16.0/pmd_rules_java_codestyle.html#avoidfinallocalvariable) (`java-codestyle`) has been deprecated
+    and will be removed with PMD 7.0.0. The rule is controversial and also contradicts other existing
+    rules such as [`LocalVariableCouldBeFinal`](https://pmd.github.io/pmd-6.16.0/pmd_rules_java_codestyle.html#localvariablecouldbefinal). If the goal is to avoid defining
+    constants in a scope smaller than the class, then the rule [`AvoidDuplicateLiterals`](https://pmd.github.io/pmd-6.16.0/pmd_rules_java_errorprone.html#avoidduplicateliterals)
+    should be used instead.
 
+*   The Apex rule [`VariableNamingConventions`](https://pmd.github.io/pmd-6.15.0/pmd_rules_apex_codestyle.html#variablenamingconventions) (`apex-codestyle`) has been deprecated and
+    will be removed with PMD 7.0.0. The rule is replaced by the more general rules
+    [`FieldNamingConventions`](https://pmd.github.io/pmd-6.15.0/pmd_rules_apex_codestyle.html#fieldnamingconventions),
+    [`FormalParameterNamingConventions`](https://pmd.github.io/pmd-6.15.0/pmd_rules_apex_codestyle.html#formalparameternamingconventions),
+    [`LocalVariableNamingConventions`](https://pmd.github.io/pmd-6.15.0/pmd_rules_apex_codestyle.html#localvariablenamingconventions), and
+    [`PropertyNamingConventions`](https://pmd.github.io/pmd-6.15.0/pmd_rules_apex_codestyle.html#propertynamingconventions).
 
-
-
-
-
-
-
-
-
-
+*   The Java rule [`LoggerIsNotStaticFinal`](https://pmd.github.io/pmd-6.15.0/pmd_rules_java_errorprone.html#loggerisnotstaticfinal) (`java-errorprone`) has been deprecated
+    and will be removed with PMD 7.0.0. The rule is replaced by [`ProperLogger`](https://pmd.github.io/pmd-6.15.0/pmd_rules_java_errorprone.html#properlogger).

docs/pages/pmd/userdocs/cpd/cpd.md

@@ -370,7 +370,7 @@ Here's a screenshot of CPD after running on the JDK 8 java.lang package:
 ## Suppression
 
 Arbitrary blocks of code can be ignored through comments on **Java**, **C/C++**, **Dart**, **Go**, **Javascript**,
-**Kotlin**, **Lua**, **Matlab**, **Objective-C**, **PL/SQL**, **Python** and **Swift** by including the keywords `CPD-OFF` and `CPD-ON`.
+**Kotlin**, **Lua**, **Matlab**, **Objective-C**, **PL/SQL**, **Python**, **Swift** and **C#** by including the keywords `CPD-OFF` and `CPD-ON`.
 
 ```java
     public Object someParameterizedFactoryMethod(int x) throws Exception {

docs/pages/release_notes.md

@@ -14,14 +14,58 @@ This is a {{ site.pmd.release_type }} release.
 
 ### New and noteworthy
 
+#### Scala cross compilation
+
+Up until now the PMD Scala module has been compiled against scala 2.13 only by default.
+However, this makes it impossible to use pmd as a library in scala projects,
+that use scala 2.12, e.g. in sbt plugins. Therefore PMD now provides cross compiled pmd-scala
+modules for both versions: **scala 2.12** and **scala 2.13**.
+
+The new modules have new maven artifactIds. The old artifactId `net.sourceforge.pmd:pmd-scala:{{ site.pmd.version }}`
+is still available, but is deprecated from now on. It has been demoted to be just a delegation to the new
+`pmd-scala_2.13` module and will be removed eventually.
+
+The coordinates for the new modules are:
+
+```
+<dependency>
+    <groupId>net.sourceforge.pmd</groupId>
+    <artifactId>pmd-scala_2.12</artifactId>
+    <version>{{ site.pmd.version }}</version>
+</dependency>
+
+<dependency>
+    <groupId>net.sourceforge.pmd</groupId>
+    <artifactId>pmd-scala_2.13</artifactId>
+    <version>{{ site.pmd.version }}</version>
+</dependency>
+```
+
+The command line version of PMD continues to use **scala 2.13**.
+
+#### New Rules
+
+*   The new Java Rule {% rule "java/codestyle/UnnecessaryCast" %} (`java-codestyle`)
+    finds casts that are unnecessary while accessing collection elements.
+
 ### Fixed Issues
 
+*   c#
+    *   [#2551](https://github.com/pmd/pmd/issues/2551): \[c#] CPD suppression with comments doesn't work
 *   java-design
     *   [#2563](https://github.com/pmd/pmd/pull/2563): \[java] UselessOverridingMethod false negative with already public methods
+*   scala
+    *   [#2547](https://github.com/pmd/pmd/pull/2547): \[scala] Add cross compilation for scala 2.12 and 2.13
 
 ### API Changes
 
+*   The maven module `net.sourceforge.pmd:pmd-scala` is deprecated. Use `net.sourceforge.pmd:pmd-scala_2.13`
+    or `net.sourceforge.pmd:pmd-scala_2.12` instead.
+
 ### External Contributions
 
+*   [#2547](https://github.com/pmd/pmd/pull/2547): \[scala] Add cross compilation for scala 2.12 and 2.13 - [João Ferreira](https://github.com/jtjeferreira)
+*   [#2567](https://github.com/pmd/pmd/pull/2567): \[c#] Fix CPD suppression with comments doesn't work - [Lixon Lookose](https://github.com/LixonLookose)
+
 {% endtocmaker %}
 

pmd-apex-jorje/pom.xml

@@ -9,6 +9,7 @@
     <groupId>net.sourceforge.pmd</groupId>
     <artifactId>pmd</artifactId>
     <version>6.25.0-SNAPSHOT</version>
+    <relativePath>../</relativePath>
   </parent>
 
   <properties>

pmd-apex/pom.xml

@@ -8,6 +8,7 @@
     <groupId>net.sourceforge.pmd</groupId>
     <artifactId>pmd</artifactId>
     <version>6.25.0-SNAPSHOT</version>
+    <relativePath>../</relativePath>
   </parent>
 
   <properties>

pmd-core/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-core/src/main/java/net/sourceforge/pmd/cpd/token/AntlrToken.java

@@ -77,7 +77,7 @@ public class AntlrToken implements GenericToken {
     }
 
     public boolean isHidden() {
-        return token.getChannel() == Lexer.HIDDEN;
+        return !isDefault();
     }
 
     public boolean isDefault() {

pmd-core/src/main/resources/rulesets/releases/6250.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+
+<ruleset name="6250"
+    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 v6.25.0
+  </description>
+
+    <rule ref="category/java/codestyle.xml/UnnecessaryCast" />
+
+</ruleset>

pmd-cpp/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-cs/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-cs/src/test/java/net/sourceforge/pmd/cpd/CsTokenizerTest.java

@@ -78,6 +78,18 @@ public class CsTokenizerTest {
         assertEquals(5, tokens.size());
     }
 
+    @Test
+    public void testIgnoreBetweenSpecialComments() {
+        tokenizer
+                .tokenize(
+                        toSourceCode("// CPD-OFF\n" + "class Foo {\n" + "  void bar() {\n" + "    int a = 1 >> 2; \n"
+                                + "    a += 1; \n" + "    a++; \n" + "    a /= 3e2; \n" + "    float f = -3.1; \n"
+                                + "    f *= 2; \n" + "    bool b = ! (f == 2.0 || f >= 1.0 && f <= 2.0) \n"
+                                + "  }\n" + "// CPD-ON\n" + "}"),
+                        tokens);
+        assertEquals(2, tokens.size()); // "}" + EOF
+    }
+
     @Test
     public void testCommentsIgnored3() {
         tokenizer.tokenize(toSourceCode("class Foo { /// class X /* aaa */ \n }"), tokens);

pmd-dart/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-dist/pom.xml

@@ -9,6 +9,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <properties>
@@ -199,7 +200,7 @@
         </dependency>
         <dependency>
             <groupId>net.sourceforge.pmd</groupId>
-            <artifactId>pmd-scala</artifactId>
+            <artifactId>pmd-scala_2.13</artifactId>
             <version>${project.version}</version>
         </dependency>
         <dependency>

pmd-doc/pom.xml

@@ -9,6 +9,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <properties>

pmd-fortran/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-go/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-groovy/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-java/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/codestyle/UnnecessaryCastRule.java

@@ -1,11 +1,12 @@
-/**
+/*
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd.lang.java.rule.migrating;
+package net.sourceforge.pmd.lang.java.rule.codestyle;
 
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 
 import net.sourceforge.pmd.lang.ast.Node;
@@ -13,10 +14,12 @@ import net.sourceforge.pmd.lang.java.ast.ASTCastExpression;
 import net.sourceforge.pmd.lang.java.ast.ASTClassOrInterfaceType;
 import net.sourceforge.pmd.lang.java.ast.ASTFieldDeclaration;
 import net.sourceforge.pmd.lang.java.ast.ASTLocalVariableDeclaration;
-import net.sourceforge.pmd.lang.java.ast.ASTName;
+import net.sourceforge.pmd.lang.java.ast.ASTTypeArgument;
 import net.sourceforge.pmd.lang.java.ast.ASTVariableDeclaratorId;
 import net.sourceforge.pmd.lang.java.rule.AbstractJavaRule;
+import net.sourceforge.pmd.lang.java.typeresolution.TypeHelper;
 import net.sourceforge.pmd.lang.symboltable.NameOccurrence;
+import net.sourceforge.pmd.lang.symboltable.ScopedNode;
 
 /**
  * This is a rule, that detects unnecessary casts when using Java 1.5 generics
@@ -34,7 +37,6 @@ import net.sourceforge.pmd.lang.symboltable.NameOccurrence;
  *      "http://sourceforge.net/p/pmd/discussion/188192/thread/276fd6f0">Java 5
  *      rules: Unnecessary casts/Iterators</a>
  */
-// TODO This is not referenced by any RuleSet?
 public class UnnecessaryCastRule extends AbstractJavaRule {
 
     private static Set<String> implClassNames = new HashSet<>();
@@ -62,36 +64,67 @@ public class UnnecessaryCastRule extends AbstractJavaRule {
         implClassNames.add("java.util.TreeSet");
         implClassNames.add("java.util.TreeMap");
         implClassNames.add("java.util.Vector");
+        implClassNames.add("Iterator");
+        implClassNames.add("java.util.Iterator");
     }
 
     @Override
     public Object visit(ASTLocalVariableDeclaration node, Object data) {
-        return process(node, data);
+        process(node, data);
+        return super.visit(node, data);
     }
 
     @Override
     public Object visit(ASTFieldDeclaration node, Object data) {
-        return process(node, data);
+        process(node, data);
+        return super.visit(node, data);
     }
 
-    private Object process(Node node, Object data) {
-        ASTClassOrInterfaceType cit = node.getFirstDescendantOfType(ASTClassOrInterfaceType.class);
-        if (cit == null || !implClassNames.contains(cit.getImage())) {
-            return data;
+    private void process(Node node, Object data) {
+        ASTClassOrInterfaceType collectionType = node.getFirstDescendantOfType(ASTClassOrInterfaceType.class);
+        if (collectionType == null || !implClassNames.contains(collectionType.getImage())) {
+            return;
         }
-        cit = cit.getFirstDescendantOfType(ASTClassOrInterfaceType.class);
+        ASTClassOrInterfaceType cit = getCollectionItemType(collectionType);
         if (cit == null) {
-            return data;
+            return;
         }
         ASTVariableDeclaratorId decl = node.getFirstDescendantOfType(ASTVariableDeclaratorId.class);
         List<NameOccurrence> usages = decl.getUsages();
         for (NameOccurrence no : usages) {
-            ASTName name = (ASTName) no.getLocation();
-            Node n = name.getParent().getParent().getParent();
-            if (n instanceof ASTCastExpression) {
-                addViolation(data, n);
+            ASTCastExpression castExpression = findCastExpression(no.getLocation());
+            if (castExpression != null) {
+                ASTClassOrInterfaceType castTarget = castExpression.getFirstDescendantOfType(ASTClassOrInterfaceType.class);
+                if (castTarget != null
+                        && cit.getImage().equals(castTarget.getImage())
+                        && !castTarget.hasDescendantOfType(ASTTypeArgument.class)) {
+                    addViolation(data, castExpression);
+                }
             }
         }
+    }
+
+    private ASTClassOrInterfaceType getCollectionItemType(ASTClassOrInterfaceType collectionType) {
+        if (TypeHelper.isA(collectionType, Map.class)) {
+            List<ASTClassOrInterfaceType> types = collectionType.findDescendantsOfType(ASTClassOrInterfaceType.class);
+            if (types.size() >= 2) {
+                return types.get(1); // the value type of the map
+            }
+        } else {
+            return collectionType.getFirstDescendantOfType(ASTClassOrInterfaceType.class);
+        }
+        return null;
+    }
+
+    private ASTCastExpression findCastExpression(ScopedNode usage) {
+        Node n = usage.getNthParent(2);
+        if (n instanceof ASTCastExpression) {
+            return (ASTCastExpression) n;
+        }
+        n = n.getParent();
+        if (n instanceof ASTCastExpression) {
+            return (ASTCastExpression) n;
+        }
         return null;
     }
 }

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

@@ -1855,6 +1855,30 @@ public class Foo {
         </example>
     </rule>
 
+    <rule name="UnnecessaryCast"
+          language="java"
+          minimumLanguageVersion="1.5"
+          since="6.24.0"
+          message="Avoid unnecessary casts"
+          class="net.sourceforge.pmd.lang.java.rule.codestyle.UnnecessaryCastRule"
+          externalInfoUrl="${pmd.website.baseurl}/pmd_rules_java_codestyle.html#unnecessarycast">
+        <description>
+This rule detects when a cast is unnecessary while accessing collection elements. This rule is mostly useful
+for old java code before generics where introduced with java 1.5.
+        </description>
+        <priority>3</priority>
+        <example>
+<![CDATA[
+public class UnnecessaryCastSample {
+    public void method() {
+        List<String> stringList = Arrays.asList("a", "b");
+        String element = (String) stringList.get(0); // this cast is unnecessary
+        String element2 = stringList.get(0);
+    }
+}
+]]>
+        </example>
+    </rule>
 
     <rule name="UnnecessaryConstructor"
           language="java"

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

@@ -105,6 +105,7 @@
     <!-- <rule ref="category/java/codestyle.xml/SuspiciousConstantFieldName" /> -->
     <!-- <rule ref="category/java/codestyle.xml/TooManyStaticImports" /> -->
     <rule ref="category/java/codestyle.xml/UnnecessaryAnnotationValueElement"/>
+    <!-- <rule ref="category/java/codestyle.xml/UnnecessaryCast" /> -->
     <rule ref="category/java/codestyle.xml/UnnecessaryConstructor"/>
     <rule ref="category/java/codestyle.xml/UnnecessaryFullyQualifiedName"/>
     <rule ref="category/java/codestyle.xml/UnnecessaryLocalBeforeReturn"/>

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

@@ -0,0 +1,12 @@
+/*
+ * 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 UnnecessaryCastTest extends PmdRuleTst {
+    // no additional unit tests
+}

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

@@ -0,0 +1,157 @@
+<?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>Basic Violations</description>
+        <expected-problems>5</expected-problems>
+        <expected-linenumbers>12,15,18,23,28</expected-linenumbers>
+        <code><![CDATA[
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.uilt.HashMap;
+
+public class UnnecessaryCastSample {
+    private Map<Integer, String> map = new HashMap<>();
+
+    public void localVars() {
+        List<String> stringList = Arrays.asList("a");
+        String element = (String) stringList.get(0);
+
+        List<Double> doubleList = new ArrayList<>();
+        Double number = (Double) doubleList.get(0);
+
+        Map<String, String> stringMap = new HashMap<>();
+        String mapData = (String) stringMap.get("a");
+    }
+
+    public void fields() {
+        map.put(1, "test");
+        String val = (String) map.get(1);
+    }
+
+    public void fields2() {
+        this.map.put(1, "test");
+        String val = (String) this.map.get(1);
+    }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Without casts there should be no violation</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.uilt.HashMap;
+
+public class UnnecessaryCastSample {
+    private Map<Integer, String> map = new HashMap<>();
+
+    public void localVars() {
+        List<String> stringList = Arrays.asList("a");
+        String element = stringList.get(0);
+
+        List<Double> doubleList = new ArrayList<>();
+        Double number = doubleList.get(0);
+    }
+
+    public void fields() {
+        map.put(1, "test");
+        String val = map.get(1);
+    }
+
+    public void fields2() {
+        this.map.put(1, "test");
+        String val = this.map.get(1);
+    }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Unnecessary casts with iterator</description>
+        <expected-problems>2</expected-problems>
+        <expected-linenumbers>10,17</expected-linenumbers>
+        <code><![CDATA[
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class UnnecessaryCastSample {
+    public void localVars() {
+        List<String> stringList = Arrays.asList("a");
+        Iterator<String> stringIt = stringList.iterator();
+        while (stringIt.hasNext()) {
+            String element = (String) stringIt.next();
+            String element2 = stringIt.next();
+        }
+
+        List<Double> doubleList = new ArrayList<>();
+        Iterator<Double> doubleIt = doubleList.iterator();
+        while (doubleIt.hasNext()) {
+            Double number = (Double) doubleIt.next();
+            Double number2 = doubleIt.next();
+        }
+    }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Avoid cast false-positives</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class UnnecessaryCastSample {
+    public void localVars() {
+        List<Number> numbers = Arrays.asList(1, 2, 3);
+        Integer myInt = (Integer) numbers.get(0);
+
+        List<Object> data = new ArrayList<>();
+        String item = (String) data.get(0);
+
+        Map<String, ?> map = new HashMap<>();
+        String dataFromMap = (String) map.get("foo");
+    }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Avoid clone false-positive</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+public class UnnecessaryCastSample {
+    public void localVars() {
+        List<String> strings = new ArrayList<>();
+        List<String> copy = (List<String>) strings.clone();
+    }
+}
+        ]]></code>
+    </test-code>
+
+    <test-code>
+        <description>Necessary Map Cast (nested generics) false-positive</description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class MapCasts {
+    private final Map<Class<?>, Map<String, ?>> resourceCaches = new ConcurrentHashMap<>(4);
+
+    @SuppressWarnings("unchecked")
+    public <T> Map<String, T> getResourceCache(Class<T> valueType) {
+        return (Map<String, T>) this.resourceCaches.computeIfAbsent(valueType, key -> new ConcurrentHashMap<>());
+    }
+}
+        ]]></code>
+    </test-code>
+</test-data>

pmd-java8/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <properties>

pmd-javascript/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>

pmd-jsp/pom.xml

@@ -8,6 +8,7 @@
         <groupId>net.sourceforge.pmd</groupId>
         <artifactId>pmd</artifactId>
         <version>6.25.0-SNAPSHOT</version>
+        <relativePath>../</relativePath>
     </parent>
 
     <build>