How do their APIs compare?

API design comparison: okhttputils vs. RxJava

These two projects operate at completely different levels of abstraction and solve different problems, so "API" means something quite different in each.

hongyangandroid/okhttputils — a thin, fluent HTTP request builder

okhttputils wraps OkHttp with a builder-pattern, callback-based API. Its surface area is organized around HTTP verbs and a shared callback interface:

• Requests are constructed with a chained builder: .url(), .addParams(), .build(), then .execute(callback). This pattern is identical across verbs, e.g. GET [README.md:L139-L164] and POST [README.md:L165-L177].
• Less common verbs (HEAD, DELETE, PUT, PATCH) reuse the same builder shape, just swapping the entry method and optionally supplying a RequestBody [README.md:L336-L350].
• Cross-cutting concerns (timeouts, logging, cookies, HTTPS/TLS) are not part of the request-builder API at all — they're configured once, globally, via a standard OkHttpClient.Builder and then registered through a static OkHttpUtils.initClient(...) call, typically in Application.onCreate() [sample-okhttp/src/main/java/com/zhy/sample_okhttp/MyApplication.java:L44-L68].
• Results are delivered via callback objects (e.g., StringCallback) with onError(Request, Exception) / onResponse(...) methods — there's no concept of streams, composition operators, or cancellation tokens beyond OkHttp's own Call.cancel(). This is a synchronous-configuration, asynchronous-callback API, typical of pre-coroutine/pre-Rx Android HTTP helpers.
• Supporting APIs are narrow utility classes rather than a cohesive framework: HttpsUtils for SSL factory construction [okhttputils/src/main/java/com/zhy/http/okhttp/https/HttpsUtils.java:L147-L186], PersistentCookieStore implementing OkHttp's CookieStore/CookieJar contracts [okhttputils/src/main/java/com/zhy/http/okhttp/cookie/store/PersistentCookieStore.java:L43-L82], and a Platform class for OS-version-specific executor/handler selection [okhttputils/src/main/java/com/zhy/http/okhttp/utils/Platform.java:L1-L24].

Overall shape: imperative, one-shot request/response, single global client, callback-driven.

reactivex/rxjava — a full reactive-composition API

RxJava's API is a type system of asynchronous/streaming sources (Completable, Single, Observable, Flowable, and the newer Streamable) with hundreds of composable operators, rather than a fixed set of "actions."

• Instead of a builder tied to a single action (like an HTTP verb), each reactive type exposes a create() factory that lets you bridge arbitrary async APIs into the reactive world. For example, Completable.create(CompletableOnSubscribe source) wraps a callback-based API and returns a Completable, internally going through RxJavaPlugins.onAssembly(new CompletableCreate(source)) [src/main/java/io/reactivex/rxjava4/core/Completable.java:L348-L379]. The CompletableOnSubscribe functional interface receives a CompletableEmitter to push completion/error events safely, including cancellation support via Cancellable [src/main/java/io/reactivex/rxjava4/core/CompletableOnSubscribe.java:L1-L23].
• Every operator/class documents its threading behavior through the @SchedulerSupport annotation, with constants like NONE (no scheduler involvement) and CUSTOM (caller must supply one) [src/main/java/io/reactivex/rxjava4/annotations/SchedulerSupport.java:L28-L38]. There's no analog to this in okhttputils — timeouts/threading there come entirely from OkHttp's own client configuration, not from the request API itself.
• RxJava is actively evolving its API surface — the Streamable type appears extensively in JMH microbenchmarks (e.g., StreamableCollectPerf, StreamableSkipPerf, StreamableConcatIterablePerf)