java.lang.IllegalStateException : Expected BEGIN_ARRAY but was BEGIN_OBJECT (Retrofit 2)

Question

当从服务器接收数据时，我收到这样的错误:java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT。什么会导致这样的错误？以及如何修复它？

我从服务器收到的 JSON:

{
  "group": [
    {
      "name": "Group1",
      "description": "Test Group 1"
    },
    {
      "name": "Group2",
      "description": "Group Name Updated"
    }
  ]
}

API接口(interface)如下:

@GET("groups")
    Observable <List<Group>> getAllGroups(@Header("Authorization") String auth,
                                   @Header("Content-type") String contentType,
                                   @Header("Accept") String accept
                                  );

我接收数据的方法:

private void getAllGroups() {
    String credentials = "admin" + ":" + "admin";
    final String basic =
            "Basic " + Base64.encodeToString(credentials.getBytes(), Base64.NO_WRAP);
    String contentType = "application/json";
    String accept = "application/json";
    Subscription subscription = App.service.getAllGroups(basic, contentType, accept)
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(groups -> {
                groupList.addAll(groups);
            }, throwable -> {
                Log.e("All group error", String.valueOf(throwable));
            });

    addSubscription(subscription);
}

类(class)组:

public class Group {

    private String name;
    private String description;

    public Group(String name, String description) {
        this.name = name;
        this.description = description;
    }

}

Answer 1

我添加了类(class)组:

public class Groups {

    @SerializedName("group")
    List<Group> group;
}

并将API接口(interface)中的代码更改为:

 @GET("groups")
    Observable <Groups> getAllGroups(@Header("Authorization") String auth,
                                   @Header("Content-type") String contentType,
                                   @Header("Accept") String accept
                                  );

应用程序开始正常工作后，不会出现错误。