OptionalRules

SUGGESTION

Simplification

View source code on GitHub

Suppression

Disable all rules by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$).* as compiler argument.

Table of contents

OptionalEmpty
OptionalOfNullable
OptionalIsEmpty
OptionalIsPresent
OptionalOrElseThrow
OptionalOrElseThrowMethodReference
OptionalEqualsOptional
OptionalFirstIteratorElement
TernaryOperatorOptionalPositiveFiltering
TernaryOperatorOptionalNegativeFiltering
MapOptionalToBoolean
MapToNullable
FlatMapToOptional
OrOrElseThrow
OptionalOrElse
StreamFlatMapOptional
StreamMapToOptionalGet
FilterOuterOptionalAfterFlatMap
MapOuterOptionalAfterFlatMap
FlatMapOuterOptionalAfterFlatMap
OptionalOrOtherOptional
OptionalIdentity
OptionalFilter
OptionalMap
OptionalStream

OptionalEmpty

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalEmpty") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalEmpty).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Optional<String> testOptionalEmpty() {
-  return Optional.ofNullable(null);
+  return Optional.empty();
 }

OptionalOfNullable

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalOfNullable") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalOfNullable).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Optional<String>> testOptionalOfNullable() {
-  return ImmutableSet.of(
-      toString() == null ? Optional.empty() : Optional.of(toString()),
-      toString() != null ? Optional.of(toString()) : Optional.empty());
+  return ImmutableSet.of(Optional.ofNullable(toString()), Optional.ofNullable(toString()));
 }

OptionalIsEmpty

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalIsEmpty") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalIsEmpty).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Boolean> testOptionalIsEmpty() {
-  return ImmutableSet.of(!Optional.empty().isPresent(), !Optional.of("foo").isPresent());
+  return ImmutableSet.of(Optional.empty().isEmpty(), Optional.of("foo").isEmpty());
 }

OptionalIsPresent

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalIsPresent") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalIsPresent).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Boolean> testOptionalIsPresent() {
-  return ImmutableSet.of(!Optional.empty().isEmpty(), !Optional.of("foo").isEmpty());
+  return ImmutableSet.of(Optional.empty().isPresent(), Optional.of("foo").isPresent());
 }

OptionalOrElseThrow

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalOrElseThrow") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalOrElseThrow).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 String testOptionalOrElseThrow() {
-  return Optional.of("foo").get();
+  return Optional.of("foo").orElseThrow();
 }

OptionalOrElseThrowMethodReference

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalOrElseThrowMethodReference") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalOrElseThrowMethodReference).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Function<Optional<Integer>, Integer> testOptionalOrElseThrowMethodReference() {
-  return Optional::get;
+  return Optional::orElseThrow;
 }

OptionalEqualsOptional

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalEqualsOptional") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalEqualsOptional).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Boolean> testOptionalEqualsOptional() {
   return ImmutableSet.of(
-      Optional.of("foo").filter("bar"::equals).isPresent(),
-      Optional.of("baz").stream().anyMatch("qux"::equals));
+      Optional.of("foo").equals(Optional.of("bar")),
+      Optional.of("baz").equals(Optional.of("qux")));
 }

OptionalFirstIteratorElement

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalFirstIteratorElement") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalFirstIteratorElement).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Optional<String>> testOptionalFirstIteratorElement() {
   return ImmutableSet.of(
-      ImmutableSet.of("foo").iterator().hasNext()
-          ? Optional.of(ImmutableSet.of("foo").iterator().next())
-          : Optional.empty(),
-      !ImmutableSet.of("foo").iterator().hasNext()
-          ? Optional.empty()
-          : Optional.of(ImmutableSet.of("foo").iterator().next()));
+      stream(ImmutableSet.of("foo").iterator()).findFirst(),
+      stream(ImmutableSet.of("foo").iterator()).findFirst());
 }

TernaryOperatorOptionalPositiveFiltering

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("TernaryOperatorOptionalPositiveFiltering") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$TernaryOperatorOptionalPositiveFiltering).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Optional<String> testTernaryOperatorOptionalPositiveFiltering() {
-  return "foo".length() > 5 ? Optional.of("foo") : Optional.empty();
+  return /* Or Optional.ofNullable (can't auto-infer). */ Optional.of("foo")
+      .filter(v -> v.length() > 5);
 }

TernaryOperatorOptionalNegativeFiltering

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("TernaryOperatorOptionalNegativeFiltering") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$TernaryOperatorOptionalNegativeFiltering).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Optional<String> testTernaryOperatorOptionalNegativeFiltering() {
-  return "foo".length() > 5 ? Optional.empty() : Optional.of("foo");
+  return /* Or Optional.ofNullable (can't auto-infer). */ Optional.of("foo")
+      .filter(v -> v.length() <= 5);
 }

MapOptionalToBoolean

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("MapOptionalToBoolean") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$MapOptionalToBoolean).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 boolean testMapOptionalToBoolean() {
-  return Optional.of("foo").map(String::isEmpty).orElse(false);
+  return Optional.of("foo").filter(String::isEmpty).isPresent();
 }

MapToNullable

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("MapToNullable") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$MapToNullable).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Optional<String>> testMapToNullable() {
   return ImmutableSet.of(
-      Optional.of(1).flatMap(n -> Optional.of(String.valueOf(n))),
-      Optional.of(2).flatMap(n -> Optional.ofNullable(String.valueOf(n))));
+      Optional.of(1).map(n -> String.valueOf(n)), Optional.of(2).map(n -> String.valueOf(n)));
 }

FlatMapToOptional

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("FlatMapToOptional") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$FlatMapToOptional).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Optional<String> testFlatMapToOptional() {
-  return Optional.of(1).map(n -> Optional.of(String.valueOf(n)).orElseThrow());
+  return Optional.of(1).flatMap(n -> Optional.of(String.valueOf(n)));
 }

OrOrElseThrow

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OrOrElseThrow") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OrOrElseThrow).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 String testOrOrElseThrow() {
-  return Optional.of("foo").orElseGet(() -> Optional.of("bar").orElseThrow());
+  return Optional.of("foo").or(() -> Optional.of("bar")).orElseThrow();
 }

OptionalOrElse

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalOrElse") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalOrElse).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<String> testOptionalOrElse() {
   return ImmutableSet.of(
-      Optional.of("foo").orElseGet(() -> "bar"), Optional.of("baz").orElseGet(() -> toString()));
+      Optional.of("foo").orElse("bar"), Optional.of("baz").orElseGet(() -> toString()));
 }

StreamFlatMapOptional

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("StreamFlatMapOptional") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$StreamFlatMapOptional).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Object> testStreamFlatMapOptional() {
   return ImmutableSet.of(
-      Stream.of(Optional.empty()).filter(Optional::isPresent).map(Optional::orElseThrow),
-      Stream.of(Optional.of("foo")).flatMap(Streams::stream));
+      Stream.of(Optional.empty()).flatMap(Optional::stream),
+      Stream.of(Optional.of("foo")).flatMap(Optional::stream));
 }

StreamMapToOptionalGet

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("StreamMapToOptionalGet") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$StreamMapToOptionalGet).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Stream<String> testStreamMapToOptionalGet() {
-  return Stream.of(1).map(n -> Optional.of(String.valueOf(n)).orElseThrow());
+  return Stream.of(1).flatMap(n -> Optional.of(String.valueOf(n)).stream());
 }

FilterOuterOptionalAfterFlatMap

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("FilterOuterOptionalAfterFlatMap") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$FilterOuterOptionalAfterFlatMap).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Optional<Integer> testFilterOuterOptionalAfterFlatMap() {
-  return Optional.of("foo").flatMap(v -> Optional.of(v.length()).filter(len -> len > 0));
+  return Optional.of("foo").flatMap(v -> Optional.of(v.length())).filter(len -> len > 0);
 }

MapOuterOptionalAfterFlatMap

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("MapOuterOptionalAfterFlatMap") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$MapOuterOptionalAfterFlatMap).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Optional<Integer> testMapOuterOptionalAfterFlatMap() {
-  return Optional.of("foo").flatMap(v -> Optional.of(v.length()).map(len -> len * 0));
+  return Optional.of("foo").flatMap(v -> Optional.of(v.length())).map(len -> len * 0);
 }

FlatMapOuterOptionalAfterFlatMap

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("FlatMapOuterOptionalAfterFlatMap") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$FlatMapOuterOptionalAfterFlatMap).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Optional<Integer> testFlatMapOuterOptionalAfterFlatMap() {
-  return Optional.of("foo").flatMap(v -> Optional.of(v.length()).flatMap(Optional::of));
+  return Optional.of("foo").flatMap(v -> Optional.of(v.length())).flatMap(Optional::of);
 }

OptionalOrOtherOptional

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalOrOtherOptional") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalOrOtherOptional).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Optional<String>> testOptionalOrOtherOptional() {
   return ImmutableSet.of(
-      Optional.of("foo").map(Optional::of).orElse(Optional.of("bar")),
-      Optional.of("baz").map(Optional::of).orElseGet(() -> Optional.of("qux")),
-      Stream.of(Optional.of("quux"), Optional.of("quuz")).flatMap(Optional::stream).findFirst(),
-      Optional.of("corge").isPresent() ? Optional.of("corge") : Optional.of("grault"));
+      Optional.of("foo").or(() -> Optional.of("bar")),
+      Optional.of("baz").or(() -> Optional.of("qux")),
+      Optional.of("quux").or(() -> Optional.of("quuz")),
+      Optional.of("corge").or(() -> Optional.of("grault")));
 }

OptionalIdentity

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalIdentity") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalIdentity).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Optional<String>> testOptionalIdentity() {
   return ImmutableSet.of(
-      Optional.of("foo").or(() -> Optional.empty()),
-      Optional.of("bar").or(Optional::empty),
-      Optional.of("baz").map(Optional::of).orElseGet(() -> Optional.empty()),
-      Optional.of("qux").map(Optional::of).orElseGet(Optional::empty),
-      Optional.of("quux").stream().findFirst(),
-      Optional.of("quuz").stream().findAny(),
-      Optional.of("corge").stream().min(String::compareTo),
-      Optional.of("grault").stream().max(String::compareTo));
+      Optional.of("foo"),
+      Optional.of("bar"),
+      Optional.of("baz"),
+      Optional.of("qux"),
+      Optional.of("quux"),
+      Optional.of("quuz"),
+      Optional.of("corge"),
+      Optional.of("grault"));
 }

OptionalFilter

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalFilter") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalFilter).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 ImmutableSet<Optional<String>> testOptionalFilter() {
   return ImmutableSet.of(
-      Optional.of("foo").stream().filter(String::isEmpty).findFirst(),
-      Optional.of("bar").stream().filter(String::isEmpty).findAny());
+      Optional.of("foo").filter(String::isEmpty), Optional.of("bar").filter(String::isEmpty));
 }

OptionalMap

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalMap") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalMap).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Optional<String> testOptionalMap() {
-  return Optional.of(1).stream().map(String::valueOf).findAny();
+  return Optional.of(1).map(String::valueOf);
 }

OptionalStream

SUGGESTION

Simplification

Suppression

Suppress false positives by adding the suppression annotation @SuppressWarnings("OptionalStream") to the enclosing element.

Disable this rule by adding -XepOpt:Refaster:NamePattern=^(?!OptionalRules\$OptionalStream).* as compiler argument.

Samples

Shows the difference in example code before and after the Refaster rule is applied.

 Stream<String> testOptionalStream() {
-  return Optional.of("foo").map(Stream::of).orElseGet(Stream::empty);
+  return Optional.of("foo").stream();
 }