Java集合List按日期升序或降序四种方法

四种方法快速预览//Method 1、不管是Date、String、Long类型的日期都可以排序，无需转换orders.sort((t1, t2) -> t2.getPayTime().compareTo(t1.getPayTime()));

//Method 2、利用stream，需要把字符串日期转换为时间戳orders = orders.stream().sorted((t1,t2) -> Long.compare(convertTimeToLong(t2.getPayTime()), convertTimeToLong(t1.getPayTime()))). collect(Collectors.toList());

//Method 3、利用Comparator接口实现，java8的写法Collections.sort(orders, Comparator.comparing(Order::getPayTime, (t1, t2) -> t2.compareTo(t1)));

//Method 4、利用Comparator接口实现，java8之前通常这样写Collections.sort(orders,new Comparator(){ @Override public int compare(Order o1, Order o2) { return o2.getPayTime().compareTo(o1.getPayTime()); }});

准备的类import lombok.AllArgsConstructor;import lombok.Data;

@AllArgsConstructor@Dataclass Order { /** * 订单号 */ private String orderNum;

/** * 付款时间 */ private String payTime;

/** * 支付金额 */ private Integer actualAmount;}

方法一import java.util.ArrayList;import java.util.List;

public class TestTimeSort { public static void main(String[] args) { Order order1 = new Order("1101", "2019-11-03 00:30:31", 100); Order order2 = new Order("1102", "2019-11-03 00:30:32", 200); Order order3 = new Order("1103", "2019-11-03 00:30:33", 300); Order order4 = new Order("1104", "2019-11-03 00:30:34", 400); Order order5 = new Order("1105", "2019-11-03 00:30:35", 500); List orders = new ArrayList(); orders.add(order2); orders.add(order1); orders.add(order4); orders.add(order3); orders.add(order5); System.out.println("------------排序前-----------------"); for (Order order : orders) { System.out.println("orderNum=" + order.getOrderNum() + ",payTime=" + order.getPayTime()); } //不管是Date、String、Long类型的日期都可以排序，无需转换 orders.sort((t1, t2) -> t2.getPayTime().compareTo(t1.getPayTime())); System.out.println("------------倒序后-----------------"); for (Order order : orders) { System.out.println("orderNum=" + order.getOrderNum() + ",payTime=" + order.getPayTime()); } }}

方法二import java.time.LocalDateTime;import java.time.ZoneId;import java.time.format.DateTimeFormatter;import java.util.ArrayList;import java.util.List;import java.util.stream.Collectors;

public class TestTimeSort { public static void main(String[] args) { Order order1 = new Order("1101", "2019-11-03 00:30:31", 100); Order order2 = new Order("1102", "2019-11-03 00:30:32", 200); Order order3 = new Order("1103", "2019-11-03 00:30:33", 300); Order order4 = new Order("1104", "2019-11-03 00:30:34", 400); Order order5 = new Order("1105", "2019-11-03 00:30:35", 500); List orders = new ArrayList(); orders.add(order2); orders.add(order1); orders.add(order4); orders.add(order3); orders.add(order5); System.out.println("------------排序前-----------------"); for (Order order : orders) { System.out.println("orderNum=" + order.getOrderNum() + ",payTime=" + order.getPayTime()); } //利用stream，需要把字符串日期转换为时间戳 orders = orders.stream().sorted((t1,t2) -> Long.compare(convertTimeToLong(t2.getPayTime()), convertTimeToLong(t1.getPayTime()))). collect(Collectors.toList()); System.out.println("------------倒序后-----------------"); for (Order order : orders) { System.out.println("orderNum=" + order.getOrderNum() + ",payTime=" + order.getPayTime()); } }

/** * 将字符串转日期成Long类型的时间戳，格式为：yyyy-MM-dd HH:mm:ss */ public static Long convertTimeToLong(String time) { DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"); LocalDateTime parse = LocalDateTime.parse(time, formatter); return LocalDateTime.from(parse).atZone(ZoneId.systemDefault()).toInstant().toEpochMilli(); } }

方法三import java.util.ArrayList;import java.util.List;import java.util.Collections;import java.util.Comparator;

public class TestTimeSort { public static void main(String[] args) { Order order1 = new Order("1101", "2019-11-03 00:30:31", 100); Order order2 = new Order("1102", "2019-11-03 00:30:32", 200); Order order3 = new Order("1103", "2019-11-03 00:30:33", 300); Order order4 = new Order("1104", "2019-11-03 00:30:34", 400); Order order5 = new Order("1105", "2019-11-03 00:30:35", 500); List orders = new ArrayList(); orders.add(order2); orders.add(order1); orders.add(order4); orders.add(order3); orders.add(order5); System.out.println("------------排序前-----------------"); for (Order order : orders) { System.out.println("orderNum=" + order.getOrderNum() + ",payTime=" + order.getPayTime()); } //利用Comparator接口实现，java8的写法 Collections.sort(orders, Comparator.comparing(Order::getPayTime, (t1, t2) -> t2.compareTo(t1))); System.out.println("------------倒序后-----------------"); for (Order order : orders) { System.out.println("orderNum=" + order.getOrderNum() + ",payTime=" + order.getPayTime()); } }}

方法四import java.util.ArrayList;import java.util.List;import java.util.Collections;import java.util.Comparator;

public class TestTimeSort { public static void main(String[] args) { Order order1 = new Order("1101", "2019-11-03 00:30:31", 100); Order order2 = new Order("1102", "2019-11-03 00:30:32", 200); Order order3 = new Order("1103", "2019-11-03 00:30:33", 300); Order order4 = new Order("1104", "2019-11-03 00:30:34", 400); Order order5 = new Order("1105", "2019-11-03 00:30:35", 500); List orders = new ArrayList(); orders.add(order2); orders.add(order1); orders.add(order4); orders.add(order3); orders.add(order5); System.out.println("------------排序前-----------------"); for (Order order : orders) { System.out.println("orderNum=" + order.getOrderNum() + ",payTime=" + order.getPayTime()); } //利用Comparator接口实现，java8之前通常这样写 Collections.sort(orders,new Comparator(){ @Override public int compare(Order o1, Order o2) { return o2.getPayTime().compareTo(o1.getPayTime()); } }); System.out.println("------------倒序后-----------------"); for (Order order : orders) { System.out.println("orderNum=" + order.getOrderNum() + ",payTime=" + order.getPayTime()); } }}

四种方法最后输出如下------------排序前-----------------orderNum=1102,payTime=2019-11-03 00:30:32orderNum=1101,payTime=2019-11-03 00:30:31orderNum=1104,payTime=2019-11-03 00:30:34orderNum=1103,payTime=2019-11-03 00:30:33orderNum=1105,payTime=2019-11-03 00:30:35------------倒序后-----------------orderNum=1105,payTime=2019-11-03 00:30:35orderNum=1104,payTime=2019-11-03 00:30:34orderNum=1103,payTime=2019-11-03 00:30:33orderNum=1102,payTime=2019-11-03 00:30:32orderNum=1101,payTime=2019-11-03 00:30:31

参考黑马教程资料