Android Studio实施Youtube API v3，找不到重复的订阅

Question

我希望代码能够识别重复或重复订阅事件中的错误，

在YouTube API引入之初，我从代码段中摘录了上述代码段，并对其进行了修改，即订阅插入：

 private List<String> getDataFromApi() throws IOException {
         String channelId = "UCEgdi0XIXXZ-qJOFPf4JSKw";
         // Create a resourceId that identifies the channel ID.
         ResourceId resourceId = new ResourceId();
         resourceId.setChannelId(channelId);
         resourceId.setKind("youtube#channel");

         // Create a snippet that contains the resourceId.
         SubscriptionSnippet snippet = new SubscriptionSnippet();
         snippet.setResourceId(resourceId);

         // Create a request to add the subscription and send the request.
         // The request identifies subscription metadata to insert as well
         // as information that the API server should return in its response.
         Subscription subscription = new Subscription();
         subscription.setSnippet(snippet);
         YouTube.Subscriptions.Insert subscriptionInsert =
                 mService.subscriptions().insert("snippet,contentDetails", subscription);
         try {
             Subscription returnedSubscription = subscriptionInsert.execute();
             if (returnedSubscription != null){
                 System.out.println("\n================== Returned Subscription ==================\n");
                 System.out.println("  - Id: " + returnedSubscription.getId());
                 System.out.println("  - Title: " + returnedSubscription.getSnippet().getTitle());
                 etNama1.setText(returnedSubscription.getId());
                 etNama2.setText(returnedSubscription.getSnippet().getTitle());
             }
         } catch (GoogleJsonResponseException e) {
             etNama1.setText(e.getDetails().getCode() + " : "
                     + e.getDetails().getMessage());
             System.err.println("GoogleJsonResponseException code: " + e.getDetails().getCode() + " : "
                     + e.getDetails().getMessage());
             e.printStackTrace();

         } catch (IOException e) {
             etNama1.setText(e.getMessage());
             System.err.println("IOException: " + e.getMessage());
             e.printStackTrace();
         } catch (Throwable t) {
             etNama1.setText(t.getMessage());
             System.err.println("Throwable: " + t.getMessage());
             t.printStackTrace();
         }

         // Print information from the API response.


     return null;

 }