This is a comprehensive exercise of stream stream collection. Before, I also wrote some common methods, such as conveyor belt: Java 8 set operation easy to use in work , this article is a supplement, more specific and structural, for everyone to learn, code can run, code can run, code can run!!! In addition, for the relevant usage of functional interface, please refer to: New features of Java 8 - functional interface

/**
	 * It is also a common skill in development to practice the integrated practice of the flow operation of the set, which makes good use of half the effort with twice the effort
	 * It's similar to the operation of sql statement
	 * 1. Find out all transaction lines occurred in 2011 and sort by transaction amount
	 * 2. Which cities have traders worked in
	 * 3. Find all traders from Cambridge and sort by name
	 * 4. Do traders work in Milan
	 * 5. Print the total of all trades of all traders in Cambridge
	 * 6. What is the smallest of all transactions
	 * 7. What is the highest of all transactions
	 * 8. Find the smallest transaction
	 */
	private List<Transaction> list;
	@Before
	public void init() {
		Trader raloul = new Trader("Raoul", "Cambridge");
		Trader mario = new Trader("Mario", "Milan");
		Trader alan = new Trader("Alan", "Cambridge");
		Trader brian = new Trader("Brian", "Cambridge");
		list=Arrays.asList(
				new Transaction(brian, 2011, 300),
				new Transaction(raloul, 2012, 1000),
				new Transaction(raloul, 2011, 400),
				new Transaction(mario, 2012, 710),
				new Transaction(mario, 2012, 700),
				new Transaction(alan, 2012, 950)
				);
				
	}
	// Find out all transaction lines occurred in 2011 and sort by transaction amount
	@Test
	public void transaction1() {
		 list.stream()
		 .filter((e)->e.getYear()==2011)
		 .sorted((t1,t2)->Integer.compare(t1.getDeal(), t2.getDeal()))
		 .forEach(System.out::println);
	}
	// Which cities have traders worked in
	@Test
	public void transaction2() {
		list.stream()
		.map(t->t.getTrader().getAddress())
		.distinct()
		.forEach(System.out::println);
	}
	// Find all traders from Cambridge and sort by name
	@Test
	public void transaction3() {
		list.stream()
		.filter(t->t.getTrader().getAddress().equals("Cambridge"))
		.map(t->t.getTrader().getName())
		.sorted()
		.forEach(System.out::println);
	}
	//Do traders work in Milan
	@Test
	public void transaction4() {
		boolean b = list.stream()
		.anyMatch(t->t.getTrader().getAddress().equals("Milan"));
	}
	
	//Print the total of all trades of all traders in Cambridge
	@Test
	public void transaction5() {
		 Optional<Integer> reduce = list.stream()
		.filter(t->t.getTrader().getAddress().equals("Cambridge"))
		.map(Transaction::getDeal)
		.reduce(Integer::sum);
		System.out.println(reduce.get());
	}
	//What is the smallest of all transactions
	@Test
	public void transaction6() {
		list.stream()
		.map(t->t.getDeal())
		.sorted()
		.limit(1)
		.forEach(System.out::println);
	}
	//What is the highest of all transactions
	@Test
	public void transaction7() {
		Optional<Integer> max = list.stream()
		.map(t->t.getDeal())
		.max(Integer::compare);
		System.out.println(max.get());
	}
	//Find the smallest transaction
	@Test
	public void transaction8() {
		Optional<Transaction> min = list.stream()
				.min((t1,t2)->Integer.compare(t1.getDeal(), t2.getDeal()));
		System.out.println(min.get());
	}