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Add comments to Maybe example in README

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Paul Campbell 2018-06-23 07:35:48 +01:00
parent d6d17a6682
commit 846bc88e4f
2 changed files with 12 additions and 1 deletions
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11
README.md
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@ -59,25 +59,36 @@ A non-final substitute for Optional with `peek()` and `stream()` methods.
class Test {
@Test
public void maybeTests() {
// Constructors: maybe(T), just(T) and nothing()
assertThat(Maybe.maybe(null)).isEqualTo(Maybe.nothing());
assertThat(Maybe.maybe(1)).isEqualTo(Maybe.just(1));
// .orElseGet(Supplier<T>)
assertThat(Maybe.nothing().orElseGet(() -> 1)).isEqualTo(1);
assertThat(Maybe.just(1).orElseGet(() -> 2)).isEqualTo(1);
// .orElse(Supplier<T>)
assertThat(Maybe.nothing().orElse(1)).isEqualTo(1);
assertThat(Maybe.just(1).orElse(2)).isEqualTo(1);
// .filter(Predicate<T>)
assertThat(Maybe.just(1).filter(v -> v > 2)).isEqualTo(Maybe.nothing());
assertThat(Maybe.just(3).filter(v -> v > 2)).isEqualTo(Maybe.just(3));
assertThat(Maybe.just(1).toOptional()).isEqualTo(Optional.of(1));
assertThat(Maybe.nothing().toOptional()).isEqualTo(Optional.empty());
// .fromOptional(Optional<T>) is deprecated
assertThat(Maybe.fromOptional(Optional.of(1))).isEqualTo(Maybe.just(1));
assertThat(Maybe.fromOptional(Optional.empty())).isEqualTo(Maybe.nothing());
// An alternative to using .fromOptional(Optional<T>)
assertThat(Optional.of(1).map(Maybe::just).orElse(Maybe::nothing)).isEqualTo(Maybe.just(1));
assertThat(Optional.empty().map(Maybe::just).orElse(Maybe::nothing)).isEqualTo(Maybe.nothing());
// .peek(Consumer<T>)
final AtomicInteger reference = new AtomicInteger(0);
assertThat(Maybe.just(1).peek(reference::set)).isEqualTo(Maybe.just(1));
assertThat(reference).hasValue(1);
assertThat(Maybe.nothing().peek(v -> reference.incrementAndGet())).isEqualTo(Maybe.nothing());
assertThat(reference).hasValue(1);
// .orElseThrow(Supplier<Exception>)
assertThatCode(() -> Maybe.just(1).orElseThrow(IllegalStateException::new)).doesNotThrowAnyException();
assertThatThrownBy(() -> Maybe.nothing().orElseThrow(IllegalStateException::new)).isInstanceOf(IllegalStateException.class);
// .stream()
assertThat(Maybe.just(1).stream()).containsExactly(1);
assertThat(Maybe.nothing().stream()).isEmpty();
}

2
src/main/java/net/kemitix/mon/maybe/Maybe.java
View file

@ -83,7 +83,7 @@ public interface Maybe<T> extends Functor<T, Maybe<?>>, MaybeStream<T>, MaybeOpt
* @return a Maybe
* @deprecated need to find a better way of converting an Optional to a Maybe, but
* without having to pass the Optional as a parameter
* Try: Optional.of(1).map(Maybe::just).orElseGet(Maybe::nothing)
* Try: Optional.of(1).map(Maybe::just).orElse(Maybe::nothing)
*/
@Deprecated
static <T> Maybe<T> fromOptional(final Optional<T> optional) {