How to change activity by receiving status code 401 in Interceptor Android

Question

When I get the status code 401 in the API, then I have to open the login activity . I don’t want to introduce change logic into every onError API method. I want a global method that is used for all APIs. Therefore, for this I created one Interceptor

public class MyInterceptor extends BaseActivity implements Interceptor {

@Override
public Response intercept(Chain chain) throws IOException {
    Response response = chain.proceed(chain.request());

    if (response.code() == 401) {

        throw new RuntimeException(" Here you got 401 from API !");
    }

    return response;
}
}

Here I add this Interceptor

OkHttpClient.Builder builder=new OkHttpClient.Builder()
            .addNetworkInterceptor(new Interceptor() {
                @Override
                public okhttp3.Response intercept(Chain chain) throws IOException {
                    Request newRequest = chain.request().newBuilder()
                            .addHeader("Content-Type", "application/json")
                            .addHeader("User-Agent", "MyApp-Android-App")
                            .build();
                    return chain.proceed(newRequest);
                }
            })
            .addNetworkInterceptor(new StethoInterceptor())
            .addNetworkInterceptor(new MyInterceptor())
            .addNetworkInterceptor(new HttpLoggingInterceptor().setLevel(HttpLoggingInterceptor.Level.BODY));

Now, where should I add a method to call activity changes. Another thing I call an API with RxRetrofit. I want a global method to handle this 401 response . Can you provide me any solution where I should put the activity change method?