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use function comparator #112

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25 changes: 19 additions & 6 deletions src/main/java/com/github/hcsp/functional/Order.java
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
import java.math.BigDecimal;
import java.time.Instant;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import java.util.TreeSet;

Expand Down Expand Up @@ -58,17 +59,29 @@ public String toString() {
// 2.然后按照订单金额排序，订单金额大的靠前；
// 3.然后按照下单时间排序，下单时间早的靠前
public static TreeSet<Order> toTreeSet(List<Order> orders) {
return null;
Comparator<Order> compareOrders = Comparator.
comparing(Order::isOpen, Boolean::compareTo).
thenComparing(Order::getAmount, BigDecimal::compareTo).reversed().
thenComparing(Order::getOrderTime, Instant::compareTo).
thenComparing(Order::getId, Integer::compareTo);
TreeSet<Order> result = new TreeSet<>(compareOrders);
result.addAll(orders);
return result;
}

public static void main(String[] args) {
Instant now = Instant.now();
System.out.println(
TreeSet<Order> orderTreeSet =
toTreeSet(
Arrays.asList(
new Order(1, now, false, new BigDecimal("1")),
new Order(2, now.minusSeconds(1), true, new BigDecimal("2")),
new Order(3, now.minusSeconds(-1), true, new BigDecimal("3")),
new Order(4, now.minusSeconds(2), false, new BigDecimal("4")))));
new Order(1, now, false, new BigDecimal("2")),
new Order(2, now, true, new BigDecimal("1")),
new Order(3, now.minusSeconds(1), true, new BigDecimal("1")),
new Order(4, now.minusSeconds(-1), true, new BigDecimal("3")),
new Order(5, now.minusSeconds(2), false, new BigDecimal("4")),
new Order(6, now.minusSeconds(2), false, new BigDecimal("4"))));
for (Order order : orderTreeSet) {
System.out.println(order);
}
}
}