import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import static java.util.Comparator.comparing;
import static java.util.stream.Collectors.*;
public class Exercise {
public static void main(String[] args) {
Trader raoul = new Trader("Raoul", "Cambridge");
Trader mario = new Trader("Mario", "Milan");
Trader alan = new Trader("Alan", "Cambridge");
Trader brian = new Trader("Brian", "Cambridge");
List<Transaction> transactions = Arrays.asList(
new Transaction(brian, 2011, 300),
new Transaction(raoul, 2012, 1000),
new Transaction(raoul, 2011, 400),
new Transaction(mario, 2012, 710),
new Transaction(mario, 2012, 700),
new Transaction(alan, 2012, 950)
);
// 找出2011年发生的所有交易,并按交易额排序
transactions.stream()
.filter(tran -> 2011 == tran.getYear())
.sorted(comparing(Transaction::getValue))
.collect(Collectors.toList());
// 交易员在哪些不同的城市工作过
transactions.stream()
.map(transaction -> transaction.getTrader().getName() + "---" + transaction.getTrader().getCity())
.distinct()
.collect(toList());
// 查找所有来自剑桥的交易员,并按姓名排序
transactions.stream()
.map(Transaction::getTrader)
.filter(trader -> "Cambridge".equals(trader.getCity()))
.sorted(comparing(Trader::getName))
.distinct()
.collect(toList());
// 返回所有交易员的姓名字符串,并按字母顺序排序
String reduce = transactions.stream()
.map(transaction -> transaction.getTrader().getName())
.distinct()
.sorted()
.reduce("", (n1, n2) -> n1 + n2);
// 有没有交易员在米兰工作的?
// .anyMatch表示一组数据中,是否包含一条或多条该数据
boolean anyMatch = transactions.stream()
.anyMatch(transaction -> transaction.getTrader().getCity().equals("Milan"));
System.out.println(anyMatch ? "有交易员在米兰" : "没有");
// 打印生活在剑桥的交易员的所有交易额
Map<String, Integer> cambridge = transactions.stream()
.filter(transaction -> transaction.getTrader().getCity().equals("Cambridge"))
.collect(groupingBy(transaction -> transaction.getTrader().getName(), summingInt(Transaction::getValue)));
System.out.println(cambridge);
// 所有交易中,最高的交易额是多少
transactions.stream()
.map(Transaction::getValue)
.reduce(0, Integer::max);
// 找到交易额最小的交易
transactions.stream()
.map(Transaction::getValue)
.reduce(Integer::min).get();
}
}