lambda表达式的一些小案例

public class Trader {
	private String name;
	private String city;
	public Trader() {
		super();
		// TODO Auto-generated constructor stub
	}
	public Trader(String name, String city) {
		super();
		this.name = name;
		this.city = city;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getCity() {
		return city;
	}
	public void setCity(String city) {
		this.city = city;
	}
	
}

public class Test {
	List<Transaction> transactions = null;
	Trader keke = new Trader("keke","hunan");
	Trader array = new Trader("array","sichuan");
	Trader object = new Trader("object","beijing");
	Trader vicky = new Trader("vicky","hunan");
	
	
	public void test(){
		Integer[] nums=  new Integer[]{2,5,1,3,6};
		Arrays.asList(nums)
		.stream().map(x->x*x)
		.forEach(System.out::println);;
		
		
	}
	
	//找出2001年发生的所有交易并按交易额排序
	@org.junit.Test
	public void test1(){
		transactions = Arrays.asList(	
				new Transaction(array, "2001", 998),
				new Transaction(keke, "2001", 999),
				new Transaction(object, "2001", 200),
				new Transaction(vicky, "2018", 1998),
				new Transaction(keke, "2017", 500));
		transactions.stream()
		.filter(x->x.getTime().equals("2001"))
		.sorted((x,y)->Integer.compare(x.getAccount(), y.getAccount()))
		.map(Transaction::getAccount)
		
		.forEach(System.out::println);
		
	}
	
	//交易员都在那些城市呆过
		
		public void test2(){
			transactions = Arrays.asList(	
					new Transaction(array, "2001", 998),
					new Transaction(keke, "2001", 999),
					new Transaction(object, "2008", 200),
					new Transaction(vicky, "2018", 1998),
					new Transaction(keke, "2017", 500));
			transactions.stream()
			.map(x->x.getTrader())
			.map(x->x.getCity())
			.distinct()
			.forEach(System.out::println);
			
		}
		
		//查找所有来自湖南的交易员，并按姓名排序
		
		public void test3(){
			transactions = Arrays.asList(	
					new Transaction(array, "2001", 998),
					new Transaction(keke, "2001", 999),
					new Transaction(object, "2008", 200),
					new Transaction(vicky, "2018", 1998),
					new Transaction(keke, "2017", 500));
			transactions.stream()
			.filter(x->x.getTrader().getCity().equals("hunan"))
			.map(Transaction::getTrader)
			.sorted((x,y)->x.getName().compareTo(y.getName()))
			
			.forEach(System.out::println);
			
		}
		//返回所有交易员的姓名字符串，并按字符顺序排序
		//@org.junit.Test
		public void test4(){
			transactions = Arrays.asList(	
					new Transaction(array, "2001", 998),
					new Transaction(keke, "2001", 999),
					new Transaction(object, "2008", 200),
					new Transaction(vicky, "2018", 1998),
					new Transaction(keke, "2017", 500));
			String string = transactions.stream()
			.map(x->x.getTrader().getName())
			.sorted()
			
			.reduce("",String::concat);
			System.out.println(string);
			System.out.println("================="
					);
			
			String string2 = transactions.stream()
					.map(x->x.getTrader().getName())
					.sorted()
					.collect(Collectors.joining(","));
			System.out.println(string2);
					
		}
		//有没有交易员在上海工作的
		@org.junit.Test
		public void test5(){
			transactions = Arrays.asList(	
					new Transaction(array, "2001", 998),
					new Transaction(keke, "2001", 999),
					new Transaction(object, "2008", 200),
					new Transaction(vicky, "2018", 1998),
					new Transaction(keke, "2017", 500));
			boolean b = transactions.stream()
					.anyMatch(x->x.getTrader().getCity().equals("shanghai"));
			
			System.out.println("有交易员是否在上海生活"+b);	
			System.out.println("==============================");
		}
		//打印所有生活在湖南的交易员的所有交易额
		@org.junit.Test
		public void test6() {
			transactions = Arrays.asList(	
					new Transaction(array, "2001", 998),
					new Transaction(keke, "2001", 999),
					new Transaction(object, "2008", 200),
					new Transaction(vicky, "2018", 1998),
					new Transaction(keke, "2017", 500));
			Optional<Integer> all = transactions.stream()
					 .filter(x->x.getTrader().getCity().equals("hunan"))
					.map(Transaction::getAccount)
					.reduce(Integer::sum);
			System.out.println("生活在湖南的交易员的所有交易额"+all.get());
			 System.out.println("========================");
		}
		//所有交易中最高的交易额
		@org.junit.Test
		public void test7() {
			transactions = Arrays.asList(	
					new Transaction(array, "2001", 998),
					new Transaction(keke, "2001", 999),
					new Transaction(object, "2008", 200),
					new Transaction(vicky, "2018", 1998),
					new Transaction(keke, "2017", 500));
				Optional<Integer> min = 	transactions.stream()
					.map(Transaction::getAccount)
					.reduce(Integer::min);
				System.out.println("所有交易中最高的交易额"+min.get());
				System.out.println("====================");
		}
		//找到交易额最小的交易
		@org.junit.Test
		public void test8() {
			transactions = Arrays.asList(	
					new Transaction(array, "2001", 998),
					new Transaction(keke, "2001", 999),
					new Transaction(object, "2008", 200),
					new Transaction(vicky, "2018", 1998),
					new Transaction(keke, "2017", 500));
					Optional<Transaction> transaction = transactions.stream()
					.sorted((x,y)->x.getAccount().compareTo(y.getAccount()))
					.findFirst();
					System.out.println(transaction.get().getTrader().getName()+transaction.get().getTrader().getCity()+transaction.get().getAccount());
			
		}
}