PMD Release Notes

31-July-2021 - 6.37.0-SNAPSHOT

The PMD team is pleased to announce PMD 6.37.0-SNAPSHOT.

This is a minor release.

New and noteworthy

Java 17 Support

This release of PMD brings support for Java 17. PMD supports JEP 409: Sealed Classes which has been promoted to be a standard language feature of Java 17.

PMD also supports JEP 406: Pattern Matching for switch (Preview) as a preview language feature. In order to analyze a project with PMD that uses these language features, you’ll need to enable it via the environment variable PMD_JAVA_OPTS and select the new language version 17-preview:

export PMD_JAVA_OPTS=--enable-preview
./run.sh pmd -language java -version 17-preview ...

Note: Support for Java 15 preview language features have been removed. The version “15-preview” is no longer available.

New rules

This release ships with 3 new Java rules.

• PrimitiveWrapperInstantiation reports usages of primitive wrapper constructors. They are deprecated since Java 9 and should not be used.

    <rule ref="category/java/bestpractices.xml/PrimitiveWrapperInstantiation" />

The rule is part of the quickstart.xml ruleset.

• SimplifiableTestAssertion suggests rewriting some test assertions to be more readable.

    <rule ref="category/java/bestpractices.xml/SimplifiableTestAssertion" />

The rule is part of the quickstart.xml ruleset.

• ReturnEmptyCollectionRatherThanNull suggests returning empty collections / arrays instead of null.

    <rule ref="category/java/errorprone.xml/ReturnEmptyCollectionRatherThanNull" />

The rule is part of the quickstart.xml ruleset.

Renamed rules

• The Java rule MissingBreakInSwitch has been renamed to ImplicitSwitchFallThrough (category error prone) to better reflect the rule’s purpose: The rule finds implicit fall-through cases in switch statements, which are most likely unexpected. The old rule name described only one way how to avoid a fall-through, namely using break but continue, throw and return avoid a fall-through as well. This enables us to improve this rule in the future.

Deprecated rules

• The following Java rules are deprecated and removed from the quickstart ruleset, as the new rule SimplifiableTestAssertion merges their functionality:
  • UseAssertEqualsInsteadOfAssertTrue
  • UseAssertNullInsteadOfAssertTrue
  • UseAssertSameInsteadOfAssertTrue
  • UseAssertTrueInsteadOfAssertEquals
  • SimplifyBooleanAssertion

• The Java rule ReturnEmptyArrayRatherThanNull is deprecated and removed from the quickstart ruleset, as the new rule ReturnEmptyCollectionRatherThanNull supersedes it.

• The following Java rules are deprecated and removed from the quickstart ruleset, as the new rule PrimitiveWrapperInstantiation merges their functionality:
  • BooleanInstantiation
  • ByteInstantiation
  • IntegerInstantiation
  • LongInstantiation
  • ShortInstantiation
• The Java rule UnnecessaryWrapperObjectCreation is deprecated with no planned replacement before PMD 7. In it’s current state, the rule is not useful as it finds only contrived cases of creating a primitive wrapper and unboxing it explicitly in the same expression. In PMD 7 this and more cases will be covered by a new rule UnnecessaryBoxing.

Fixed Issues

• apex
  • #3201: [apex] ApexCRUDViolation doesn’t report Database class DMLs, inline no-arg object instantiations and inline list initialization
  • #3329: [apex] ApexCRUDViolation doesn’t report SOQL for loops
• core
  • #1603: [core] Language version comparison
  • #3377: [core] NPE when specifying report file in current directory in PMD CLI
  • #3387: [core] CPD should avoid unnecessary copies when running with –skip-lexical-errors
• java-bestpractices
  • #2908: [java] Merge Junit assertion simplification rules
  • #3235: [java] UseTryWithResources false positive when closeable is provided as a method argument or class field
• java-errorprone
  • #3361: [java] Rename rule MissingBreakInSwitch to ImplicitSwitchFallThrough
  • #3382: [java] New rule ReturnEmptyCollectionRatherThanNull

API Changes

Experimental APIs

• The AST types and APIs around Sealed Classes are not experimental anymore:
  • ASTClassOrInterfaceDeclaration#isSealed, ASTClassOrInterfaceDeclaration#isNonSealed, ASTClassOrInterfaceDeclaration#getPermittedSubclasses
  • ASTPermitsList

Internal API

Those APIs are not intended to be used by clients, and will be hidden or removed with PMD 7.0.0. You can identify them with the @InternalApi annotation. You’ll also get a deprecation warning.

• The inner class net.sourceforge.pmd.cpd.TokenEntry.State is considered to be internal API. It will probably be moved away with PMD 7.

External Contributions

• #3367: [apex] Check SOQL CRUD on for loops - Jonathan Wiesel
• #3373: [apex] Add ApexCRUDViolation support for database class, inline no-arg object construction DML and inline list initialization DML - Jonathan Wiesel
• #3385: [core] CPD: Optimize –skip-lexical-errors option - Woongsik Choi
• #3388: [doc] Add Code Inspector in the list of tools - Julien Delange