Release 4.0.0 of the Checker Framework

Version 4.0.0 (2026-04-07)

User-visible changes

To run the Checker Framework, you need to use a JDK 17 or later version of javac. That is, you need to use JDK 17 or later when compiling your code.

The Checker Framework can type-check any Java project, including projects that compile to Java 8 or 11 bytecodes and run on JRE versions 8 or 11. That is, your code can run under any release of Java, from Java 8 onward.

The type qualifiers and utility libraries in checker-qual.jar and checker-util.jar still use Java 11 bytecode. Thus, they may be used in projects that run under Java 11 or later.

Changes since version 3.0.0

Since version 3.0.0, 91 authors have made over 4500 commits and closed over 600 issues. Thanks to everyone who contributed!

New checkers include:

• The Index Checker warns about out-of-bounds accesses to arrays and strings.
• The Initialized Fields Checker warns if a constructor does not initialize a field.
• The Resource Leak Checker guarantees that every resource is closed rather than leaked. Examples of resources are a channel, executor, ExecutionControl, file, FileLock, Formatter, reader, Scanner, socket, stream, writer, etc.
• The SQL Quotes Checker helps prevent SQL injection vulnerabilities.

New command-line arguments include:

• -AskipFiles, -AonlyFiles
• -AassumeSideEffectFree, -AassumeDeterministic, -AassumePure, -AassumePureGetters
• -AuseConservativeDefaultsForUncheckedCode
• -AignoreRawTypeArguments
• -AwarnRedundantAnnotations
• -Ainfer=ajava, -AinferOutputDirectory, -AinferOutputOriginal, -AshowWpiFailedInferences
• -AshowSuppressWarningsStrings, -AwarnUnneededSuppressionsExceptions
• -AshowPrefixInWarningMessages
• -AstubNoWarnIfNotFound, -AstubWarnNote, -AmergeStubsWithSource
• -Aonelinemsg, -AdumpOnErrors, -AexceptionLineSeparator
• -ApermitMissingJdk, -AparseAllJdk
• -AslowTypecheckingSeconds
• -Aversion, -AprintGitProperties
• You can pass an option to only a particular checker (not all checkers) by using an underscore prefix.

Other improvements include thousands of enhancements and bug fixes -- too many to list here.

Implementation details

All previously-deprecated methods and classes have been removed. If your project builds upon the Checker Framework, we suggest that you upgrade to version 3.55.1, resolve all the deprecation warnings, then upgrade to version 4.0.0.

Checker Framework 3.55.1

Version 3.55.1 (2026-04-03)

No user-visible changes.

Checker Framework 3.54.1

Version 3.55.0 (2026-04-02)

User-visible changes

The Checker Framework runs under JDK 26 -- that is, it runs on a version 26 JVM.

Removed deprecated command-line option -AskipDirs; use -AskipFiles.

Implementation details

In AnnotatedTypeMirror:

• Renamed getEffectiveAnnotation*() to getAnnotation*().
• Renamed hasEffectiveAnnotation*() to hasAnnotation*().

Removed deprecated method ObjectCreationNode.getConstructor(); use
getTypeToInstantiate().

Closed issues

#7079, #7489, #7539.

Checker Framework 3.54.0

Version 3.54.0 (2026-03-02)

User-visible changes

Command-line arguments:

• Added -AinferOutputDirectory.
• Removed long-deprecated -Alint=forbidnonnullarraycomponents.

New command-line argument -Aonelinemsg puts error messages on a single line. This is useful when using a tool that only shows the first line of the error.

The command-line argument -Anomsgtext surrounds the error key with brackets instead of parenthesis. This matches Java error messages.

Implementation details

In AnnotatedTypeFactory, canonicalAnnotation() returns a non-null value.

In AnnotationClassLoader:

• Renamed hasWellDefinedTargetMetaAnnotation() to isTypeQualifierAnnotation(). The method now returns true for annotations bearing @InvisibleQualifier or @SubtypeOf, in addition to the existing @Target(TYPE_USE) check.

In TestDiagnostic:

• Renamed field message to key.
• Added new nullable field message for the full message without the key.

Removed classes and methods that have been deprecated for more than two years.

Closed issues

#6874, #7471, #7475, #7486.

Checker Framework 3.53.1

Version 3.53.1 (2026-02-02)

Closed issues

#4858, #6141, #6620, #7360, #7388.

Checker Framework 3.53.0

Version 3.53.0 (2026-01-06)

Implementation details

In AbstractAnalysis, added getStoreBefore(Tree), getStoreBefore(Node),
getStoreAfter(Tree), and getStoreAfter(Node).

In GenericAnnotatedTypeFactory, removed getStoreBefore(Set<Node>) and getStoreAfter(Set<Node>).

Closed issues

#2358.

Checker Framework 3.52.1

Version 3.52.1 (2025-12-02)

User-visible changes:

Added Opt.ifPresentOrElse() method.

Closed issues:
#7243, #7398.

Checker Framework 3.52.0

Version 3.52.0 (2025-11-04)

Implementation details:

In CFAbstractAnalysis, renamed defaultCreateAbstractValue to getCfValue

In GenericAnnotatedTypeFactory:

• renamed performFlowAnalysis to performFlowAnalysisForClass
• renamed checkAndPerformFlowAnalysis to performFlowAnalysisForClassOnce

Closed issues:

#6629, #7341, #7346.

Checker Framework 3.51.1

Version 3.51.1 (2025-10-01)

Closed issues:

#6623, #7250.

Checker Framework 3.51.0

Version 3.51.0 (2025-09-10)

User-visible changes:

If you supply --add-exports flags when you run the Checker Framework, you need to add:
--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED.

Implementation details:

In CFGVisualizeOptions:

• renamed isPDF() to isPdfOutput()
• renamed isString() to isStringOutput()

Dataflow Framework:

• In playground package, renamed *Playground.java to *Pdf.java

Closed issues:

#7229, #7241, #7248, #7258.