[S3] Register TransferListener before submitting a transfer job (#961)

Author: Karthikeyan

CHANGELOG.md

@@ -4,6 +4,9 @@
 
 ### Bug Fixes
 
+* **Amazon S3**
+  * Fix a bug where the `TransferListener` is not triggered when the preferred network type is not available. See [issue #958](https://github.com/aws-amplify/aws-sdk-android/issues/958) for details.
+  
 * **AWS Core Runtime**
   * Fixed a bug where generating RSA keys for encryption of the credentials failed due to `setKeySize(int)` method not available in Android API level 18. See [issue #964](https://github.com/aws-amplify/aws-sdk-android/issues/964) for details.
 

aws-android-sdk-s3/src/main/java/com/amazonaws/mobileconnectors/s3/transferutility/TransferUtility.java

@@ -389,8 +389,11 @@ public TransferObserver download(String bucket, String key, File file, TransferL
             file.delete();
         }
 
+        // Creating the observer before the job is submitted because the listener needs to be registered
+        // with TransferStatusUpdater when the job is being submitted.
+        TransferObserver transferObserver = new TransferObserver(recordId, dbUtil, bucket, key, file, listener);
         submitTransferJob(TRANSFER_ADD, recordId);
-        return new TransferObserver(recordId, dbUtil, bucket, key, file, listener);
+        return transferObserver;
     }
 
     /**
@@ -551,8 +554,11 @@ public TransferObserver upload(String bucket, String key, File file, ObjectMetad
             recordId = Integer.parseInt(uri.getLastPathSegment());
         }
 
+        // Creating the observer before the job is submitted because the listener needs to be registered
+        // with TransferStatusUpdater when the job is being submitted.
+        TransferObserver transferObserver = new TransferObserver(recordId, dbUtil, bucket, key, file, listener);
         submitTransferJob(TRANSFER_ADD, recordId);
-        return new TransferObserver(recordId, dbUtil, bucket, key, file, listener);
+        return transferObserver;
     }
 
     /**