Stream API introduced from Java 8 There are many convenient processes for operating Collection (Although it will be even more now) I will list it like a memo.
What is Stream API? Recognize that Stream itself is not a Collection element such as List or Map, but a pipeline for adding generation processing, intermediate processing, and termination processing to elements such as arrays and lists and replacing them with new elements.
Stream#of
Stream<String> stream = Stream.of("a","b","c");
Collection#stream
Generate from List
List<String> list = Arrays.asList("a","b","c");
Stream<String> stream = list.stream();
Generated from Map
Map<String,String> map = new HashMap<>();
Stream<Entry<String,String>> stream = map.entrySet().stream();
Arrays#Stream
String[] array = {"a","b","c"};
Stream<String> stream = Arrays.stream(array);
BufferedReader#lines
BufferedReader reader = new BufferedReader(newInputStreamReader(System.in, directory));
Stream<String> reader.lines();