如何在flatmap上创建链运算符

Question

在下面的代码中，在companion对象中，create方法应该返回Single。正如代码所示，我使用的最后一个操作符是flatmap（），用于将改装对象转换为Maybe。只是为了确保它不是空的。然而，当我使用这个操作符时

                 .flatMap {retrofit->Maybe.just(retrofit)}

我无法链接任何其他操作符来将上述flatmap返回的值转换为Single。请让我知道为什么我不能在上述代码上链接任何其他操作员，也请查找下面发布的代码

代码

interface WikiApiService {
@GET("api.php")
fun hitCountCheck(
    @Query("action") action: String,
    @Query("format") format: String,
    @Query("list") list: String,
    @Query("srsearch") srsearch: String
):
        Observable<ResponseObjectModelForQuery.ResultOfQuery>

@GET("api.php")
fun hitContinue2(
    @Query("action") action: String,
    @Query("format") format: String,
    @Query("list") list: String,
    @Query("srsearch") srsearch: String
):
        Observable<ResponseObjectModelForContinueSrOffset.ResultOfContinueSrOffset>

@GET("api.php")
fun hitContinue3(
    @Query("action") action: String,
    @Query("format") format: String,
    @Query("list") list: String,
    @Query("srsearch") srsearch: String
):
        Observable<ResponseObjectModelForContinueContinue.Continue>

//why do we need a companion object
companion object {
    fun create(): Single<WikiApiService>? {
        return Single.just(
            Retrofit.Builder()
                .addCallAdapterFactory(
                    RxJava2CallAdapterFactory.create()
                )
                .addConverterFactory(
                    GsonConverterFactory.create()
                )
                .baseUrl("https://en.wikipedia.org/w/")
                .build())
            //workin.flatMap { Maybe.just(it.create(WikiApiService::class.java)).toSingle()}
            .flatMap {retrofit->Maybe.just(retrofit)}
            .//cant chain any further operators

            }
    }
}

Answer 1

你有没有尝试使用平地图也许（）来代替：

    companion object {
    fun create(): Single<WikiApiService>? {
        return Single.just(
            Retrofit.Builder()
                .addCallAdapterFactory(
                    RxJava2CallAdapterFactory.create()
                )
                .addConverterFactory(
                    GsonConverterFactory.create()
                )
                .baseUrl("https://en.wikipedia.org/w/")
                .build())
            //workin.flatMap {  Maybe.just(it.create(WikiApiService::class.java)).toSingle()}
            .flatMapMaybe {retrofit->Maybe.just(retrofit)}
            .//cant chain any further operators

            }
    }
}

？或者根据您希望链接的内容将可能转换为单个：

    companion object {
    fun create(): Single<WikiApiService>? {
        return Single.just(
            Retrofit.Builder()
                .addCallAdapterFactory(
                    RxJava2CallAdapterFactory.create()
                )
                .addConverterFactory(
                    GsonConverterFactory.create()
                )
                .baseUrl("https://en.wikipedia.org/w/")
                .build())
            //workin.flatMap {  Maybe.just(it.create(WikiApiService::class.java)).toSingle()}
            .flatMap {retrofit->Maybe.just(retrofit).toSingle() }
            .//cant chain any further operators

            }
    }
}