Extract a repeated @Nullable invocation into a local variable
io.moderne.nullability.ExtractRepeatedNullableInvocationToLocalio.moderne.recipe:rewrite-nullabilityWhen the same side-effect-free @Nullable method invocation (textually identical receiver, name, and no arguments — e.g. source.get()) appears two or more times in one block, hoists it into a single local @Nullable Type x = source.get(); declared just before the first use and replaces every occurrence with x. NullAway cannot refine a @Nullable return across two separate calls — the second could return a different value — so if (source.get() != null) { source.get().foo(); } is rejected; one local gives the checker a single narrowing point. The rewrite is strictly gated: the call must be provably @Nullable (resolved from the nullability model), side-effect free (only a no-argument getter-style call whose receiver is a simple identifier or this, never an argument-bearing or unresolved-type call), all occurrences must be in the same block, and the receiver must not be reassigned anywhere in that block (which could change the value between calls). A pure call evaluated once rather than N times yields the same value, so runtime behavior is unchanged. Idempotent and conservative; only Java sources are modified.
Usage
This recipe has no required configuration options. You’ll need the Moderne CLI configured before running the command below.
mod run . --recipe io.moderne.nullability.ExtractRepeatedNullableInvocationToLocalIf the recipe isn’t available locally, install it with:
mod config recipes jar install io.moderne.recipe:rewrite-nullability:0.3.1Options
| Name | Type | Description |
|---|---|---|
annotatedPackages | String | Comma-separated package prefixes to limit the fix to (matching NullAway's AnnotatedPackages option). When unset, the recipe fixes all packages.e.g. com.example |
Data tables
Structured output this recipe can produce.
- Null-safety fixes by rungEach residual null-safety fix applied, tagged with the precedence rung that produced it, so the share bottoming out at a last-resort `requireNonNull` assertion can be tracked.
io.moderne.nullability.table.NullFixes - Declined null-safety fixes needing reviewEach site the recipe declined to auto-fix because the fix is a design decision (the value is explicitly `null` on some path, so the slot likely should be `@Nullable`), for human triage.
io.moderne.nullability.table.DeclinedNullFixes - Source files that had resultsSource files that were modified by the recipe run.
org.openrewrite.table.SourcesFileResults - Source files that had search resultsSearch results that were found during the recipe run.
org.openrewrite.table.SearchResults - Source files that errored on a recipeThe details of all errors produced by a recipe run.
org.openrewrite.table.SourcesFileErrors - Recipe performanceStatistics used in analyzing the performance of recipes.
org.openrewrite.table.RecipeRunStats