我试图根据选项值返回Either
值。我的目标是如果存在该选项,则返回Either.right(),否则代码应返回Either.left()。
我使用Java 8和vavr 0.9.2
我想避免有条件的禁忌
public Either<String, Integer> doSomething() {
Optional<Integer> optionalInteger = Optional.of(Integer.MIN_VALUE);
Option<Integer> integerOption = Option.ofOptional(optionalInteger);
return integerOption.map(value -> {
//some other actions here
return Either.right(value);
}).orElse(() -> {
//some other checks her also
return Either.left("Error message");
});
}
编译器失败并显示此消息
Error:(58, 7) java: no suitable method found for orElse(()->Either[...]age"))
method io.vavr.control.Option.orElse(io.vavr.control.Option<? extends io.vavr.control.Either<java.lang.Object,java.lang.Integer>>) is not applicable
(argument mismatch; io.vavr.control.Option is not a functional interface
multiple non-overriding abstract methods found in interface io.vavr.control.Option)
method io.vavr.control.Option.orElse(java.util.function.Supplier<? extends io.vavr.control.Option<? extends io.vavr.control.Either<java.lang.Object,java.lang.Integer>>>) is not applicable
(argument mismatch; bad return type in lambda expression
no instance(s) of type variable(s) L,R exist so that io.vavr.control.Either<L,R> conforms to io.vavr.control.Option<? extends io.vavr.control.Either<java.lang.Object,java.lang.Integer>>)
最佳答案
orElse
返回Option<T>
,而doSomething
返回类型需要Either<String, Integer>
。
而是尝试使用返回getOrElse
的T
:
public Either<String, Integer> doSomething() {
// ...
return integerOption.map(
Either::<String, Integer>right).getOrElse(
() -> Either.left("Error message"));
}