How To Return A Variable From A Listener Method

In the below code, I am declaring class variable downloadUrl which is set later in the method ImageLoad. And i am trying to set the variable and return it when the method is called

Solution 1:

You can do it as follows:

publicclassImageActions {

publicinterfaceOntaskCompleted{
   voidonSuccess(Uri returnurl);
   voidonfail();
}

private Uri downloadUrl;

publicvoidImageLoad(final OntaskCompleted listener)
{
    FirebaseStoragestorage= FirebaseStorage.getInstance();
    StorageReferencestorageRef= storage.getReferenceFromUrl("gs://apptest.appspot.com");

    Urifile= Uri.fromFile(newFile("sdcard/DCIM/Camera/1466831822883.jpg"));

    StorageMetadatametadata=newStorageMetadata.Builder().setContentType("image/jpeg").build();

    UploadTaskuploadTask= storageRef.child("images/"+file.getLastPathSegment()).putFile(file, metadata);

    uploadTask.addOnProgressListener(newOnProgressListener<UploadTask.TaskSnapshot>() {
        @OverridepublicvoidonProgress(UploadTask.TaskSnapshot taskSnapshot) {

        }
    }).addOnPausedListener(newOnPausedListener<UploadTask.TaskSnapshot>() {
        @OverridepublicvoidonPaused(UploadTask.TaskSnapshot taskSnapshot) {
            System.out.println("Upload is paused");
        }
    }).addOnFailureListener(newOnFailureListener() {
        @OverridepublicvoidonFailure(@NonNull Exception exception) {
            // Handle unsuccessful uploads
            listener.onfail();
        }
    }).addOnSuccessListener(newOnSuccessListener<UploadTask.TaskSnapshot>() {
        @OverridepublicvoidonSuccess(UploadTask.TaskSnapshot taskSnapshot) {
            // Handle successful uploads on complete
            downloadUrl = taskSnapshot.getMetadata().getDownloadUrl();
                  System.out.println("Upload completed");  
            listenr.onSuccess(downloadurl)              
        }
    });

 }
}

Now call this function as follows:

ImageLoadObject.ImageLoad(new OntaskCompleted(){

   @Override
   void onSuccess(Uri url){
      //Here you will get the url after upload complete
   }
   @Override
   void onFail(){

   }
});

Hope this helps you.