blocks.stream()
      .map(block ‑> block.squash())
      .filter(block ‑> block.getColor() != YELLOW)
      .forEach(block ‑> block.display());

		Stream.of(1, 2, 3, 4, 5)
		      .peek((e) -> System.out.println("Stream element:" + e))
		      .filter((e)-> e>1)
		      .peek((e) -> System.out.println("Filtered element:" + e))
		      .map(String::valueOf)
		      .peek((e) -> System.out.println("Mapped element:" + e))
		      .collect(Collectors.toList());

Stream element:1
Stream element:2
Filtered element:2
Mapped element:2
Stream element:3
Filtered element:3
Mapped element:3
Stream element:4
Filtered element:4
Mapped element:4
Stream element:5
Filtered element:5
Mapped element:5

The intermediate operations are classifiable in:

Stateful
    distinct()
    sorted()
    limit (long l)
    skip (long l)

Stateless
    map (Function f)
    flatMap (Function f)
    filter (Predicate p)
    peek (Consumer c)

No storage. A stream is not a data structure that stores elements; instead, it conveys elements from a source such as a data structure, an array, a generator function, or an I/O channel, through a pipeline of computational operations.

Stream<Integer> stream = Stream.of(1, 2, 3);
		
long count = stream.count();
System.out.println(count);
//count = stream.count(); // java.lang.IllegalStateException: stream has already been operated upon or closed
		
Stream<Integer> stream2 = Stream.of(1, 2, 3);
		
Stream<Integer> stream3 = stream2.sorted();
// long count2 = stream2.count(); // java.lang.IllegalStateException: stream has already been operated upon or closed

// long count2 = stream2.count(); // java.lang.IllegalStateException: stream has already been operated upon or closed

		
Stream<Integer> stream4 = Stream.of(1, 3, 4, 0);
stream4.filter(e->e>0);
stream4.map(e->e); // Exception ...

		List<Integer> list = new ArrayList<>(100);
		for(int i=0; i<1000; i++)
			list.add(i);

		Thread t1 = new Thread(() -> {
			try {
				Thread.sleep(1000);
				for (int i=10;i<1000;i++) {
					list.add(i);
					System.out.println(Thread.currentThread().getName() + i);
				}	
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		});

		t1.start();
		Thread.sleep(1000);
		list.stream().peek(i->System.out.println(Thread.currentThread().getName())).forEach(System.out::println);

Exception in thread "main" java.util.ConcurrentModificationException
	at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(Unknown Source)

		Integer[] array = new Integer[1100];
		for(int i=0; i<100; i++)
			array[i] = i;

		Thread t1 = new Thread(() -> {
			try {
				Thread.sleep(1100);
				for (int i=100;i<1000;i++) {
					array[i] = i;
					System.out.println(Thread.currentThread().getName() + ":" + i);
				}	
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		});

		t1.start();
		Thread.sleep(1000);
		Stream.of(array).peek(e->{
			try {
				Thread.sleep(1);
			} catch (InterruptedException e1) {
				e1.printStackTrace();
			}
		}).forEach(System.out::println);
		
		System.out.println(Arrays.toString(array));

0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Thread-0:100
Thread-0:101
Thread-0:102
Thread-0:103

...

Thread-0:997
Thread-0:998
Thread-0:999
16
17
18
19
20
21
22

....

100
101

...