无法为io.reactivex.Observable创建调用适配器。

Question

我将使用简单的get方法向我的服务器（它是一个Rails应用程序）发送请求，并使用RxJava和Retrofit获取结果。我所做的事情如下：

我的接口：

public interface ApiCall {
    String SERVICE_ENDPOINT = "https://198.50.214.15";
    @GET("/api/post")
    io.reactivex.Observable<Post> getPost();
}

我的模型是这样的：

public class Post
{
    @SerializedName("id")
    private String id;
    @SerializedName("body")
    private String body;
    @SerializedName("title")
    private String title;

    public String getId ()
    {
        return id;
    }


    public String getBody ()
    {
        return body;
    }


    public String getTitle ()
    {
        return title;
    }

}

这是我在活动中所做的事情：

public class Javax extends AppCompatActivity {
    RecyclerView rvListContainer;
    postAdapter postAdapter;
    List<String> messageList=new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_javax);

        rvListContainer=(RecyclerView)findViewById(R.id.recyclerView);
        postAdapter=new postAdapter(messageList);

        rvListContainer.setAdapter(postAdapter);
    }
    @Override
    protected void onResume() {
        super.onResume();
        Retrofit retrofit=new Retrofit.Builder()
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .addConverterFactory(GsonConverterFactory.create())
                .baseUrl("https://198.50.214.15")
                .build();
        ApiCall apiService=retrofit.create(ApiCall.class);

        Observable<Post> observable=apiService.getPost();

        observable.subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(responseData -> {
                    messageList.add(responseData.getTitle());
                    postAdapter.notifyDataSetChanged();
                });

    }
}

我不知道为什么会出现这个错误，说我适配器有问题。我也已经在 Gradle 中包含了适配器:

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.hussein.sqlitedatabase, PID: 19445
java.lang.RuntimeException: Unable to resume activity {com.example.hussein.sqlitedatabase/com.example.hussein.sqlitedatabase.Javax}: java.lang.IllegalArgumentException: Unable to create call adapter for io.reactivex.Observable<com.example.hussein.sqlitedatabase.Post>
    for method ApiCall.getPost
    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2964)
    at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2993)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
    at android.app.ActivityThread.access$800(ActivityThread.java:151)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
    at android.os.Handler.dispatchMessage(Handler.java:110)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:5292)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
    at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.IllegalArgumentException: Unable to create call adapter for io.reactivex.Observable<com.example.hussein.sqlitedatabase.Post>
    for method ApiCall.getPost
    at retrofit2.ServiceMethod$Builder.methodError(ServiceMethod.java:751)
    at retrofit2.ServiceMethod$Builder.createCallAdapter(ServiceMethod.java:236)
    at retrofit2.ServiceMethod$Builder.build(ServiceMethod.java:161)
    at retrofit2.Retrofit.loadServiceMethod(Retrofit.java:169)
    at retrofit2.Retrofit$1.invoke(Retrofit.java:146)
    at $Proxy0.getPost(Native Method)
    at com.example.hussein.sqlitedatabase.Javax.onResume(Javax.java:42)
    at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1197)
    at android.app.Activity.performResume(Activity.java:5343)
    at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2950)
        ... 12 more
 Caused by: java.lang.IllegalArgumentException: Could not locate call adapter for io.reactivex.Observable<com.example.hussein.sqlitedatabase.Post>.
  Tried:
   * retrofit2.adapter.rxjava.RxJavaCallAdapterFactory
   * retrofit2.ExecutorCallAdapterFactory
    at retrofit2.Retrofit.nextCallAdapter(Retrofit.java:240)
    at retrofit2.Retrofit.callAdapter(Retrofit.java:204)
    at retrofit2.ServiceMethod$Builder.createCallAdapter(ServiceMethod.java:234)
        ... 20 more

这是我的Gradle依赖：

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    compile 'com.android.support:appcompat-v7:25.3.1'
    testCompile 'junit:junit:4.12'

    compile 'com.squareup.retrofit2:retrofit:2.2.0'

    compile 'com.android.support:recyclerview-v7:25.3.1'
    compile 'com.android.support:design:25.3.1'

    compile 'io.reactivex.rxjava2:rxandroid:2.0.1'
    compile 'io.reactivex.rxjava2:rxjava:2.0.1'

    compile 'com.jakewharton.retrofit:retrofit2-rxjava2-adapter:1.0.0'
    compile 'com.squareup.retrofit2:adapter-rxjava:2.0.2'

    compile 'com.squareup.retrofit2:converter-gson:2.0.0'

    compile 'com.google.code.gson:gson:2.4'

}

- Hussein Ojaghi

Answer 1

您需要告诉Retrofit您想使用RxJava 2，使用以下方式：

addCallAdapterFactory(RxJava2CallAdapterFactory.create())

因此，要创建Retrofit对象，您将需要类似于以下内容：

Retrofit retrofit = new Retrofit.Builder()
    .baseUrl(SERVICE_ENDPOINT)
    .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
    .build();

- GVillani82

---

谢谢，但我遇到的另一个问题是关于我的URL，它显示为--->无法连接到/198.50.214.15:80。 - Hussein Ojaghi

我改成了 .baseUrl("http://198.50.214.15/")，但仍然出现相同的错误。 - Hussein Ojaghi

这是包含 RxJava2CallAdapterFactory 的库的链接：https://github.com/square/retrofit/tree/master/retrofit-adapters/rxjava2。 - VKostenc

Answer 2

我遇到了同样的问题。你可以添加Jake Wharton库的依赖，而不是添加新的仓库：

implementation 'com.jakewharton.retrofit:retrofit2-rxjava2-adapter:1.0.0'

然后您可以添加工厂：

Retrofit retrofit = new Retrofit.Builder()
    .baseUrl("https://api.example.com")
    .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
    .build();

适配器版本为2并不意味着它是用于RxJava 2的，就像我之前认为的那样。

implementation 'com.squareup.retrofit2:adapter-rxjava2:2.1.0'

- Raut Darpan

---

@ShaktisinhJadeja 谢谢，感觉很好能帮到你。 - Raut Darpan

请使用com.squareup.retrofit2:adapter-rxjava2。注意你漏掉了数字2 :) - dleal

RxJava2CallAdapterFactory已过时 - 现在RxJavaCallAdapterFactory支持全部。 - Konrad Krakowiak

Answer 3

问题出在使用的库上。 我已经替换了。

implementation 'com.squareup.retrofit2:adapter-rxjava:2.4.0'

随着

implementation 'com.squareup.retrofit2:adapter-rxjava2:2.4.0'

并使用

Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(BASE_URL).client(client)
                .addConverterFactory(GsonConverterFactory.create(gson))
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .build();

- Anudeep

---

你的两个成绩条目是相同的吗？ - Nadeem Shukoor

我已经将rxjava:2.4.0替换为rxjava2:2.4.0。 - Anudeep

Answer 4

使用Android Studio 2022.3.1（长颈鹿版）和Retrofit 2.9.0，问题已得到修复。

proguard-rules.pro

# With R8 full mode generic signatures are stripped for classes that are not
# kept. Suspend functions are wrapped in continuations where the type 
argument
# is used.
-keep,allowobfuscation,allowshrinking class kotlin.coroutines.Continuation
-keep,allowobfuscation,allowshrinking interface retrofit2.Call
-keep,allowobfuscation,allowshrinking class retrofit2.Response

# R8 full mode strips generic signatures from return types if not kept.
-if interface * { @retrofit2.http.* public *** *(...); }
-keep,allowoptimization,allowshrinking,allowobfuscation class <3>

- norbDEV

---

https://github.com/square/retrofit/issues/3898 - norbDEV