public static void main(String[] args) {

List<String> stringCollection = new ArrayList<>();

stringCollection.add("ddd2");

stringCollection.add("aaa2");

stringCollection.add("bbb1");

stringCollection.add("aaa1");

stringCollection.add("bbb3");

stringCollection.add("ccc");

stringCollection.add("bbb2");

stringCollection.add("ddd1");

// filtering

stringCollection

.stream()

.filter((s) -> s.startsWith("a"))

.forEach(System.out::println);

// "aaa2", "aaa1"

// sorting

stringCollection

.stream()

.sorted()

.filter((s) -> s.startsWith("a"))

.forEach(System.out::println);

// "aaa1", "aaa2"

// mapping

stringCollection

.stream()

.map(String::toUpperCase)

.sorted((a, b) -> b.compareTo(a))

.forEach(System.out::println);

// "DDD2", "DDD1", "CCC", "BBB3", "BBB2", "AAA2", "AAA1"

// matching

boolean anyStartsWithA = stringCollection

.stream()

.anyMatch((s) -> s.startsWith("a"));

System.out.println(anyStartsWithA); // true

boolean allStartsWithA = stringCollection

.stream()

.allMatch((s) -> s.startsWith("a"));

System.out.println(allStartsWithA); // false

boolean noneStartsWithZ = stringCollection

.stream()

.noneMatch((s) -> s.startsWith("z"));

System.out.println(noneStartsWithZ); // true

// counting

long startsWithB = stringCollection

.stream()

.filter((s) -> s.startsWith("b"))

.count();

System.out.println(startsWithB); // 3

// reducing

Optional<String> reduced =

stringCollection

.stream()

.sorted()

.reduce((s1, s2) -> s1 + "#" + s2);

reduced.ifPresent(System.out::println);

// "aaa1#aaa2#bbb1#bbb2#bbb3#ccc#ddd1#ddd2"

}