Getting the number of objects stored under S3 bucket

I need to know the number of files that are stored under S3 bucket. Currently, ObjectListening doesn't has a method such as count or numberOfObject.

However, it has a method that will return a List of S3ObjectSummary.

public java.util.List<S3ObjectSummary> getObjectSummaries()

Since it is a List, I can call size() method but is it accurate and right thing to assume that the size of getObjectSummaries() List is the same number of objects that are stored under a bucket?