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Annotate null-checked method parameters with @Nullable

org.openrewrite.staticanalysis.AnnotateNullableParameters

Add @Nullable to parameters of public methods that are explicitly checked for null. By default org.jspecify.annotations.Nullable is used, but through the nullableAnnotationClass option a custom annotation can be provided. When providing a custom nullableAnnotationClass that annotation should be meta annotated with @Target(TYPE_USE). This recipe scans for methods that do not already have parameters annotated with @Nullable annotation and checks their usages for potential null checks.

Recipe source​

GitHub, Issue Tracker, Maven Central

This recipe is available under the Moderne Source Available License.

Options​

TypeNameDescriptionExample
StringnullableAnnotationClassOptional. The fully qualified name of the @Nullable annotation. The annotation should be meta annotated with @Target(TYPE_USE). Defaults to org.jspecify.annotations.Nullableorg.jspecify.annotations.Nullable

Example​

Parameters​
ParameterValue
nullableAnnotationClassnull
Before​
public class PersonBuilder {
    private String name = "Unknown";

    public PersonBuilder setName(String name) {
        if (name == null) {
            return this;
        }
        this.name = name.substring(0, 1).toUpperCase() + name.substring(1);
        return this;
    }
}
After​
import org.jspecify.annotations.Nullable;

public class PersonBuilder {
    private String name = "Unknown";

    public PersonBuilder setName(@Nullable String name) {
        if (name == null) {
            return this;
        }
        this.name = name.substring(0, 1).toUpperCase() + name.substring(1);
        return this;
    }
}

Usage​

This recipe has no required configuration options. It can be activated by adding a dependency on org.openrewrite.recipe:rewrite-static-analysis in your build file or by running a shell command (in which case no build changes are needed):

  1. Add the following to your build.gradle file:
build.gradle
plugins {
    id("org.openrewrite.rewrite") version("latest.release")
}

rewrite {
    activeRecipe("org.openrewrite.staticanalysis.AnnotateNullableParameters")
    setExportDatatables(true)
}

repositories {
    mavenCentral()
}

dependencies {
    rewrite("org.openrewrite.recipe:rewrite-static-analysis:2.12.0")
}
  1. Run gradle rewriteRun to run the recipe.

See how this recipe works across multiple open-source repositories​

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Data Tables​

Source files that had results​

org.openrewrite.table.SourcesFileResults

Source files that were modified by the recipe run.

Column NameDescription
Source path before the runThe source path of the file before the run. null when a source file was created during the run.
Source path after the runA recipe may modify the source path. This is the path after the run. null when a source file was deleted during the run.
Parent of the recipe that made changesIn a hierarchical recipe, the parent of the recipe that made a change. Empty if this is the root of a hierarchy or if the recipe is not hierarchical at all.
Recipe that made changesThe specific recipe that made a change.
Estimated time savingAn estimated effort that a developer to fix manually instead of using this recipe, in unit of seconds.
CycleThe recipe cycle in which the change was made.

Contributors​

Stefano Dalla Palma, Tim te Beek