1.x: Add PMD code checking tool to the build process

build.gradle

@@ -6,6 +6,7 @@ buildscript {
 description = 'RxJava: Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.'
 
 apply plugin: 'java'
+apply plugin: 'pmd'
 apply plugin: 'jacoco'
 apply plugin: 'nebula.rxjava-project'
 
@@ -60,3 +61,40 @@ jacocoTestReport {
 }
 
 build.dependsOn jacocoTestReport
+
+pmd {
+    toolVersion = '5.4.2'
+    ignoreFailures = true
+    sourceSets = [sourceSets.main]
+    ruleSets = []
+    ruleSetFiles = files('pmd.xml')
+
+}
+
+pmdMain {
+    reports {
+        html.enabled = true
+        xml.enabled = true
+    }
+}
+
+build.dependsOn pmdMain
+
+task pmdPrint(dependsOn: 'pmdMain') << {
+    File file = new File('build/reports/pmd/main.xml')
+    if (file.exists()) {
+
+        println("Listing first 100 PMD violations")
+
+        file.eachLine { line, count ->
+            if (count <= 100) {
+               println(line)
+            }
+        }
+
+    } else {
+        println("PMD file not found.")
+    }
+}
+
+build.dependsOn pmdPrint

pmd.xml

@@ -0,0 +1,230 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ruleset xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         name="pmd"
+         xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 http://pmd.sourceforge.net/ruleset_2_0_0.xsd">
+   <description>RxJava PMD ruleset</description>
+   <rule ref="rulesets/java/design.xml/AbstractClassWithoutAbstractMethod"/>
+   <rule ref="rulesets/java/design.xml/AbstractClassWithoutAnyMethod"/>
+   <rule ref="rulesets/java/design.xml/AccessorClassGeneration"/>
+   <rule ref="rulesets/java/optimizations.xml/AddEmptyString"/>
+   <rule ref="rulesets/java/strings.xml/AppendCharacterWithChar"/>
+   <rule ref="rulesets/java/design.xml/AssignmentToNonFinalStatic"/>
+   <rule ref="rulesets/java/controversial.xml/AvoidAccessibilityAlteration"/>
+   <rule ref="rulesets/java/optimizations.xml/AvoidArrayLoops"/>
+   <rule ref="rulesets/java/migrating.xml/AvoidAssertAsIdentifier"/>
+   <rule ref="rulesets/java/basic.xml/AvoidBranchingStatementAsLastInLoop"/>
+   <rule ref="rulesets/java/finalizers.xml/AvoidCallingFinalize"/>
+   <rule ref="rulesets/java/strictexception.xml/AvoidCatchingGenericException"/>
+   <rule ref="rulesets/java/strictexception.xml/AvoidCatchingNPE"/>
+   <rule ref="rulesets/java/design.xml/AvoidConstantsInterface"/>
+   <rule ref="rulesets/java/basic.xml/AvoidDecimalLiteralsInBigDecimalConstructor"/>
+   <rule ref="rulesets/java/naming.xml/AvoidDollarSigns"/>
+   <rule ref="rulesets/java/migrating.xml/AvoidEnumAsIdentifier"/>
+   <rule ref="rulesets/java/controversial.xml/AvoidFinalLocalVariable"/>
+   <rule ref="rulesets/java/design.xml/AvoidInstanceofChecksInCatchClause"/>
+   <rule ref="rulesets/java/strictexception.xml/AvoidLosingExceptionInformation"/>
+   <rule ref="rulesets/java/basic.xml/AvoidMultipleUnaryOperators"/>
+   <rule ref="rulesets/java/controversial.xml/AvoidPrefixingMethodParameters"/>
+   <rule ref="rulesets/java/logging-java.xml/AvoidPrintStackTrace"/>
+   <rule ref="rulesets/java/design.xml/AvoidProtectedFieldInFinalClass"/>
+   <rule ref="rulesets/java/design.xml/AvoidProtectedMethodInFinalClassNotExtending"/>
+   <rule ref="rulesets/java/strictexception.xml/AvoidRethrowingException"/>
+   <rule ref="rulesets/java/strings.xml/AvoidStringBufferField"/>
+   <rule ref="rulesets/java/design.xml/AvoidSynchronizedAtMethodLevel"/>
+   <rule ref="rulesets/java/basic.xml/AvoidThreadGroup"/>
+   <rule ref="rulesets/java/strictexception.xml/AvoidThrowingNewInstanceOfSameException"/>
+   <rule ref="rulesets/java/strictexception.xml/AvoidThrowingRawExceptionTypes"/>
+   <rule ref="rulesets/java/basic.xml/AvoidUsingHardCodedIP"/>
+   <rule ref="rulesets/java/controversial.xml/AvoidUsingNativeCode"/>
+   <rule ref="rulesets/java/basic.xml/AvoidUsingOctalValues"/>
+   <rule ref="rulesets/java/controversial.xml/AvoidUsingShortType"/>
+   <rule ref="rulesets/java/design.xml/BadComparison"/>
+   <rule ref="rulesets/java/basic.xml/BigIntegerInstantiation"/>
+   <rule ref="rulesets/java/naming.xml/BooleanGetMethodName"/>
+   <rule ref="rulesets/java/basic.xml/BooleanInstantiation"/>
+   <rule ref="rulesets/java/basic.xml/BrokenNullCheck"/>
+   <rule ref="rulesets/java/migrating.xml/ByteInstantiation"/>
+   <rule ref="rulesets/java/android.xml/CallSuperFirst"/>
+   <rule ref="rulesets/java/android.xml/CallSuperLast"/>
+   <rule ref="rulesets/java/basic.xml/CheckResultSet"/>
+   <rule ref="rulesets/java/basic.xml/CheckSkipResult"/>
+   <rule ref="rulesets/java/basic.xml/ClassCastExceptionWithToArray"/>
+   <rule ref="rulesets/java/naming.xml/ClassNamingConventions"/>
+   <rule ref="rulesets/java/design.xml/ClassWithOnlyPrivateConstructorsShouldBeFinal"/>
+   <rule ref="rulesets/java/clone.xml/CloneMethodMustImplementCloneable"/>
+   <rule ref="rulesets/java/clone.xml/CloneThrowsCloneNotSupportedException"/>
+   <rule ref="rulesets/java/design.xml/CloseResource"/>
+   <rule ref="rulesets/java/comments.xml/CommentContent"/>
+   <rule ref="rulesets/java/strings.xml/ConsecutiveAppendsShouldReuse"/>
+   <rule ref="rulesets/java/strings.xml/ConsecutiveLiteralAppends"/>
+   <rule ref="rulesets/java/design.xml/ConstructorCallsOverridableMethod"/>
+   <rule ref="rulesets/java/coupling.xml/CouplingBetweenObjects"/>
+   <rule ref="rulesets/java/design.xml/DefaultLabelNotLastInSwitchStmt"/>
+   <rule ref="rulesets/java/controversial.xml/DoNotCallGarbageCollectionExplicitly"/>
+   <rule ref="rulesets/java/j2ee.xml/DoNotCallSystemExit"/>
+   <rule ref="rulesets/java/strictexception.xml/DoNotExtendJavaLangError"/>
+   <rule ref="rulesets/java/android.xml/DoNotHardCodeSDCard"/>
+   <rule ref="rulesets/java/strictexception.xml/DoNotThrowExceptionInFinally"/>
+   <rule ref="rulesets/java/basic.xml/DontCallThreadRun"/>
+   <rule ref="rulesets/java/imports.xml/DontImportJavaLang"/>
+   <rule ref="rulesets/java/basic.xml/DontUseFloatTypeForLoopIndices"/>
+   <rule ref="rulesets/java/basic.xml/DoubleCheckedLocking"/>
+   <rule ref="rulesets/java/imports.xml/DuplicateImports"/>
+   <rule ref="rulesets/java/empty.xml/EmptyCatchBlock"/>
+   <rule ref="rulesets/java/finalizers.xml/EmptyFinalizer"/>
+   <rule ref="rulesets/java/empty.xml/EmptyFinallyBlock"/>
+   <rule ref="rulesets/java/empty.xml/EmptyInitializer"/>
+   <rule ref="rulesets/java/empty.xml/EmptyStatementBlock"/>
+   <rule ref="rulesets/java/empty.xml/EmptyStatementNotInLoop"/>
+   <rule ref="rulesets/java/empty.xml/EmptyStaticInitializer"/>
+   <rule ref="rulesets/java/empty.xml/EmptySwitchStatements"/>
+   <rule ref="rulesets/java/empty.xml/EmptySynchronizedBlock"/>
+   <rule ref="rulesets/java/empty.xml/EmptyTryBlock"/>
+   <rule ref="rulesets/java/empty.xml/EmptyWhileStmt"/>
+   <rule ref="rulesets/java/design.xml/EqualsNull"/>
+   <rule ref="rulesets/java/strictexception.xml/ExceptionAsFlowControl"/>
+   <rule ref="rulesets/java/coupling.xml/ExcessiveImports"/>
+   <rule ref="rulesets/java/basic.xml/ExtendsObject"/>
+   <rule ref="rulesets/java/design.xml/FieldDeclarationsShouldBeAtStartOfClass"/>
+   <rule ref="rulesets/java/design.xml/FinalFieldCouldBeStatic"/>
+   <rule ref="rulesets/java/finalizers.xml/FinalizeDoesNotCallSuperFinalize"/>
+   <rule ref="rulesets/java/finalizers.xml/FinalizeOnlyCallsSuperFinalize"/>
+   <rule ref="rulesets/java/finalizers.xml/FinalizeOverloaded"/>
+   <rule ref="rulesets/java/finalizers.xml/FinalizeShouldBeProtected"/>
+   <rule ref="rulesets/java/basic.xml/ForLoopShouldBeWhileLoop"/>
+   <rule ref="rulesets/java/braces.xml/ForLoopsMustUseBraces"/>
+   <rule ref="rulesets/java/logging-jakarta-commons.xml/GuardDebugLogging"/>
+   <rule ref="rulesets/java/logging-jakarta-commons.xml/GuardLogStatement"/>
+   <rule ref="rulesets/java/logging-java.xml/GuardLogStatementJavaUtil"/>
+   <rule ref="rulesets/java/design.xml/IdempotentOperations"/>
+   <rule ref="rulesets/java/braces.xml/IfElseStmtsMustUseBraces"/>
+   <rule ref="rulesets/java/braces.xml/IfStmtsMustUseBraces"/>
+   <rule ref="rulesets/java/design.xml/ImmutableField"/>
+   <rule ref="rulesets/java/imports.xml/ImportFromSamePackage"/>
+   <rule ref="rulesets/java/strings.xml/InefficientEmptyStringCheck"/>
+   <rule ref="rulesets/java/strings.xml/InefficientStringBuffering"/>
+   <rule ref="rulesets/java/design.xml/InstantiationToGetClass"/>
+   <rule ref="rulesets/java/strings.xml/InsufficientStringBufferDeclaration"/>
+   <rule ref="rulesets/java/migrating.xml/IntegerInstantiation"/>
+   <rule ref="rulesets/java/migrating.xml/JUnit4SuitesShouldUseSuiteAnnotation"/>
+   <rule ref="rulesets/java/migrating.xml/JUnit4TestShouldUseAfterAnnotation"/>
+   <rule ref="rulesets/java/migrating.xml/JUnit4TestShouldUseBeforeAnnotation"/>
+   <rule ref="rulesets/java/migrating.xml/JUnit4TestShouldUseTestAnnotation"/>
+   <rule ref="rulesets/java/junit.xml/JUnitAssertionsShouldIncludeMessage"/>
+   <rule ref="rulesets/java/junit.xml/JUnitSpelling"/>
+   <rule ref="rulesets/java/junit.xml/JUnitStaticSuite"/>
+   <rule ref="rulesets/java/junit.xml/JUnitTestContainsTooManyAsserts"/>
+   <rule ref="rulesets/java/junit.xml/JUnitTestsShouldIncludeAssert"/>
+   <rule ref="rulesets/java/migrating.xml/JUnitUseExpected"/>
+   <rule ref="rulesets/java/basic.xml/JumbledIncrementer"/>
+   <rule ref="rulesets/java/j2ee.xml/LocalHomeNamingConvention"/>
+   <rule ref="rulesets/java/j2ee.xml/LocalInterfaceSessionNamingConvention"/>
+   <rule ref="rulesets/java/logging-java.xml/LoggerIsNotStaticFinal"/>
+   <rule ref="rulesets/java/design.xml/LogicInversion"/>
+   <rule ref="rulesets/java/migrating.xml/LongInstantiation"/>
+   <rule ref="rulesets/java/coupling.xml/LooseCoupling"/>
+   <rule ref="rulesets/java/j2ee.xml/MDBAndSessionBeanNamingConvention"/>
+   <rule ref="rulesets/java/naming.xml/MethodNamingConventions"/>
+   <rule ref="rulesets/java/sunsecure.xml/MethodReturnsInternalArray"/>
+   <rule ref="rulesets/java/naming.xml/MethodWithSameNameAsEnclosingClass"/>
+   <rule ref="rulesets/java/naming.xml/MisleadingVariableName"/>
+   <rule ref="rulesets/java/basic.xml/MisplacedNullCheck"/>
+   <rule ref="rulesets/java/design.xml/MissingBreakInSwitch"/>
+   <rule ref="rulesets/java/javabeans.xml/MissingSerialVersionUID"/>
+   <rule ref="rulesets/java/design.xml/MissingStaticMethodInNonInstantiatableClass"/>
+   <rule ref="rulesets/java/logging-java.xml/MoreThanOneLogger"/>
+   <rule ref="rulesets/java/codesize.xml/NcssConstructorCount"/>
+   <rule ref="rulesets/java/codesize.xml/NcssMethodCount"/>
+   <rule ref="rulesets/java/codesize.xml/NcssTypeCount"/>
+   <rule ref="rulesets/java/naming.xml/NoPackage"/>
+   <rule ref="rulesets/java/design.xml/NonCaseLabelInSwitchStatement"/>
+   <rule ref="rulesets/java/design.xml/NonStaticInitializer"/>
+   <rule ref="rulesets/java/design.xml/NonThreadSafeSingleton"/>
+   <rule ref="rulesets/java/controversial.xml/OneDeclarationPerLine"/>
+   <rule ref="rulesets/java/design.xml/OptimizableToArrayCall"/>
+   <rule ref="rulesets/java/basic.xml/OverrideBothEqualsAndHashcode"/>
+   <rule ref="rulesets/java/naming.xml/PackageCase"/>
+   <rule ref="rulesets/java/design.xml/PositionLiteralsFirstInCaseInsensitiveComparisons"/>
+   <rule ref="rulesets/java/design.xml/PositionLiteralsFirstInComparisons"/>
+   <rule ref="rulesets/java/optimizations.xml/PrematureDeclaration"/>
+   <rule ref="rulesets/java/design.xml/PreserveStackTrace"/>
+   <rule ref="rulesets/java/clone.xml/ProperCloneImplementation"/>
+   <rule ref="rulesets/java/logging-jakarta-commons.xml/ProperLogger"/>
+   <rule ref="rulesets/java/optimizations.xml/RedundantFieldInitializer"/>
+   <rule ref="rulesets/java/j2ee.xml/RemoteInterfaceNamingConvention"/>
+   <rule ref="rulesets/java/j2ee.xml/RemoteSessionInterfaceNamingConvention"/>
+   <rule ref="rulesets/java/migrating.xml/ReplaceEnumerationWithIterator"/>
+   <rule ref="rulesets/java/migrating.xml/ReplaceHashtableWithMap"/>
+   <rule ref="rulesets/java/migrating.xml/ReplaceVectorWithList"/>
+   <rule ref="rulesets/java/design.xml/ReturnEmptyArrayRatherThanNull"/>
+   <rule ref="rulesets/java/basic.xml/ReturnFromFinallyBlock"/>
+   <rule ref="rulesets/java/migrating.xml/ShortInstantiation"/>
+   <rule ref="rulesets/java/naming.xml/ShortMethodName"/>
+   <rule ref="rulesets/java/strictexception.xml/SignatureDeclareThrowsException"/>
+   <rule ref="rulesets/java/design.xml/SimpleDateFormatNeedsLocale"/>
+   <rule ref="rulesets/java/junit.xml/SimplifyBooleanAssertion"/>
+   <rule ref="rulesets/java/design.xml/SimplifyBooleanExpressions"/>
+   <rule ref="rulesets/java/design.xml/SimplifyBooleanReturns"/>
+   <rule ref="rulesets/java/design.xml/SimplifyConditional"/>
+   <rule ref="rulesets/java/optimizations.xml/SimplifyStartsWith"/>
+   <rule ref="rulesets/java/design.xml/SingularField"/>
+   <rule ref="rulesets/java/j2ee.xml/StaticEJBFieldShouldBeFinal"/>
+   <rule ref="rulesets/java/strings.xml/StringBufferInstantiationWithChar"/>
+   <rule ref="rulesets/java/strings.xml/StringInstantiation"/>
+   <rule ref="rulesets/java/strings.xml/StringToString"/>
+   <rule ref="rulesets/java/naming.xml/SuspiciousConstantFieldName"/>
+   <rule ref="rulesets/java/naming.xml/SuspiciousEqualsMethodName"/>
+   <rule ref="rulesets/java/naming.xml/SuspiciousHashcodeMethodName"/>
+   <rule ref="rulesets/java/controversial.xml/SuspiciousOctalEscape"/>
+   <rule ref="rulesets/java/design.xml/SwitchDensity"/>
+   <rule ref="rulesets/java/design.xml/SwitchStmtsShouldHaveDefault"/>
+   <rule ref="rulesets/java/logging-java.xml/SystemPrintln"/>
+   <rule ref="rulesets/java/junit.xml/TestClassWithoutTestCases"/>
+   <rule ref="rulesets/java/design.xml/TooFewBranchesForASwitchStatement"/>
+   <rule ref="rulesets/java/imports.xml/TooManyStaticImports"/>
+   <rule ref="rulesets/java/design.xml/UncommentedEmptyConstructor"/>
+   <rule ref="rulesets/java/design.xml/UncommentedEmptyMethodBody"/>
+   <rule ref="rulesets/java/basic.xml/UnconditionalIfStatement"/>
+   <rule ref="rulesets/java/junit.xml/UnnecessaryBooleanAssertion"/>
+   <rule ref="rulesets/java/strings.xml/UnnecessaryCaseChange"/>
+   <rule ref="rulesets/java/controversial.xml/UnnecessaryConstructor"/>
+   <rule ref="rulesets/java/unnecessary.xml/UnnecessaryConversionTemporary"/>
+   <rule ref="rulesets/java/unnecessary.xml/UnnecessaryFinalModifier"/>
+   <rule ref="rulesets/java/imports.xml/UnnecessaryFullyQualifiedName"/>
+   <rule ref="rulesets/java/design.xml/UnnecessaryLocalBeforeReturn"/>
+   <rule ref="rulesets/java/controversial.xml/UnnecessaryParentheses"/>
+   <rule ref="rulesets/java/unnecessary.xml/UnnecessaryReturn"/>
+   <rule ref="rulesets/java/optimizations.xml/UnnecessaryWrapperObjectCreation"/>
+   <rule ref="rulesets/java/design.xml/UnsynchronizedStaticDateFormatter"/>
+   <rule ref="rulesets/java/unusedcode.xml/UnusedFormalParameter"/>
+   <rule ref="rulesets/java/imports.xml/UnusedImports"/>
+   <rule ref="rulesets/java/unusedcode.xml/UnusedLocalVariable"/>
+   <rule ref="rulesets/java/unusedcode.xml/UnusedModifier"/>
+   <rule ref="rulesets/java/unnecessary.xml/UnusedNullCheckInEquals"/>
+   <rule ref="rulesets/java/unusedcode.xml/UnusedPrivateField"/>
+   <rule ref="rulesets/java/unusedcode.xml/UnusedPrivateMethod"/>
+   <rule ref="rulesets/java/optimizations.xml/UseArrayListInsteadOfVector"/>
+   <rule ref="rulesets/java/optimizations.xml/UseArraysAsList"/>
+   <rule ref="rulesets/java/junit.xml/UseAssertEqualsInsteadOfAssertTrue"/>
+   <rule ref="rulesets/java/junit.xml/UseAssertNullInsteadOfAssertTrue"/>
+   <rule ref="rulesets/java/junit.xml/UseAssertSameInsteadOfAssertTrue"/>
+   <rule ref="rulesets/java/junit.xml/UseAssertTrueInsteadOfAssertEquals"/>
+   <rule ref="rulesets/java/design.xml/UseCollectionIsEmpty"/>
+   <rule ref="rulesets/java/controversial.xml/UseConcurrentHashMap"/>
+   <rule ref="rulesets/java/logging-jakarta-commons.xml/UseCorrectExceptionLogging"/>
+   <rule ref="rulesets/java/strings.xml/UseEqualsToCompareStrings"/>
+   <rule ref="rulesets/java/strings.xml/UseIndexOfChar"/>
+   <rule ref="rulesets/java/design.xml/UseLocaleWithCaseConversions"/>
+   <rule ref="rulesets/java/design.xml/UseNotifyAllInsteadOfNotify"/>
+   <rule ref="rulesets/java/controversial.xml/UseObjectForClearerAPI"/>
+   <rule ref="rulesets/java/j2ee.xml/UseProperClassLoader"/>
+   <rule ref="rulesets/java/optimizations.xml/UseStringBufferForStringAppends"/>
+   <rule ref="rulesets/java/strings.xml/UseStringBufferLength"/>
+   <rule ref="rulesets/java/design.xml/UseUtilityClass"/>
+   <rule ref="rulesets/java/unnecessary.xml/UselessOperationOnImmutable"/>
+   <rule ref="rulesets/java/unnecessary.xml/UselessOverridingMethod"/>
+   <rule ref="rulesets/java/strings.xml/UselessStringValueOf"/>
+   <rule ref="rulesets/java/naming.xml/VariableNamingConventions"/>
+   <rule ref="rulesets/java/braces.xml/WhileLoopsMustUseBraces"/>
+</ruleset>