How can I change a class to an interface in this condition?

Question

Here is my definition：

public abstract class APICallback<T extends CommonModel.APIDataModel> implements Callback<CommonModel<T>> 

I found that I can not convert APICallback back to Callback.

What is the problem?

How can I do it correctly?

Thank you!

----Update----

In fact I am using retrofit , I defined APICallback implements retrofit.Callback

Here is the exact code :

public abstract class APICallback<T extends CommonModel.APIDataModel> implements Callback<CommonModel<T>> {
private Context context;

public APICallback(Context context) {
    this.context = context;
}

public abstract void onResponse(T response);

@Override
public void onResponse(Response<CommonModel<T>> response, Retrofit retrofit) {
    T data = response.body().data;

    if (response.body().isSuccess()) {
        onResponse(data);
        onEnd();
    } else {
        dispatchError(response.body());
    }
}

@Override
public void onFailure(Throwable t) {        
    LogUtils.d("Network error or exception", t.getMessage());
    ViewUtils.showMessage(t.getMessage());
    onEnd();
}

public void dispatchError(CommonModel<T> response) {   
    LogUtils.d("API error", response.toString());
    ViewUtils.showMessage(response.data.msg);
    onEnd();
}

public void onEnd() {
    if (context instanceof BaseActivity) {
        ((BaseActivity) context).getLoading().hide();
    }
}

I am using it like this:

getClient().login(u, p).enqueue(new APICallback<UserModel>(this) {
        @Override
        public void onResponse(UserModel response) {

            Intent intent = new Intent(LoginActivity.this, MainActivity.class);
            startActivity(intent);
            finish();
        }

    });

enqueue :

void enqueue(Callback<T> callback);

login :

Call<UserModel> login(@Field("user_name") String userName, @Field("user_password") String userPassword);

The compiler tell me that can not convert anonymous APICallback<UserModel> to Callback<UserModel>

I am confused.

Answer 1

I didn't notice that my login method definition doesn't match Callback<CommonModel<T>> .

After I change it to

Call<CommonModel<UserModel>> login(@Field("user_name") String userName, @Field("user_password") String userPassword);

everything is ok.