Esercizi

universitystudyingsubject-2201

Esercizi

Ingegneria del Software

L21_JavaStreamParte2.pdf

es. 1

String prefix = "kek";

Stream<String> elementi = Stream.of(“author”, “auto”, “autocorrect”, “begin”, “big”, “bigger”, “biggish”)
	.filter(x -> x.substring(0, prefix.length()).equals(prefix));

es. 2

String str = Stream.of(“to”, “speak”, “the”, “truth”, “and”, “pay”,
“your”, “debts”)
	.map(x -> x.substring(0, 1))
	.reduce("", (accumulator, prefixChar) -> accumulator + prefixChar);

es. 3

Stream<int> x = Stream.of(new ArrayList<int>(Array.asList(2, 3, 4)), ...)
	.filter(x -> x.size() == 3
			  && x.get(0) + x.get(1) > x.get(2)
			  && x.get(1) + x.get(2) > x.get(0)
			  && x.get(2) + x.get(0) > x.get(1))
	.map(x -> x.stream().sum());

es. 4

List<int> listaNumeriInteri = new ArrayList<int>(Array.asList(2, 3, 5, 7, 8));

List<int[]> l = IntStream.rangeClosed(0, listaNumeriInteri.length() - 3)
	.mapToObj(x -> new int[] {listaNumeriInteri.get(x),
						 listaNumeriInteri.get(x + 1),
						 listaNumeriInteri.get(x + 2)})
	.filter(x -> x.size() == 3 // todo: occhio che non è un arraylist
			  && x.get(0) + x.get(1) > x.get(2)
			  && x.get(1) + x.get(2) > x.get(0)
			  && x.get(2) + x.get(0) > x.get(1))
	.collect(Collectors.toList())

es. 5

List<int> myList = new ArrayList(2, 4, 5);

bool isOrdered = IntStream.rangeClosed(0, myList.length())
	.filter(x -> myList.get(x) > myList.get(x + 1))
	.findAny()
	.isEmpty()

System.out.println("la lista è " + isOrdered ? "ORDINATA" : "NON ORDINATA")