Interface is an integral part of java and has become so powerful over the years, that it shifted the way a Java programmer thinks.
To use the partitioningBy Collector, you have to pass the Collectors.partitioningBy in the collect() method of Stream API.
how you can iterate over a List, be it ArrayList, LinkedList or any other. Basic loop to iteration to Stream API. And also, figure out which one is best suitable for our code.
Using Functional interfaces provided by Java we can become more functional. And Knowing them would help us utilise Stream API fully