Best way to read file and process content in java

I'm curious about the best way to read files and then process each line of the file. Assuming that the resource that needs to be read from can grow in size (e.g. a very large file) and the reading and processing of files can be swapped with a different implementation (e.g. reading an xml source instead of a file containing Strings). Please consider the following approaches:

1. 
   

   Create 2 services. First service is used to extract data from the file and return a list. Second service takes the list and iterate thru it to process each item. Pros for this approach is that it adheres to SRP and makes it posible to switch services(e.g. get the data from a different source like XML JSON). The only con i could think about is that the performance hit of iterating thru the collection again (first time is when reading then putting in a collection) to do the processing.

   
   


2. 
   

   Have only 1 service that will do both tasks. This way you can do the processing inside the initial loop. Trade offs would be the coupling between the reading and processing functionality which breaks the SRP.

   
   

If you have other suggestions on how to accomplish this all ideas are very welcome! TYIA!!!