1 public class DateUtils extends org.apache.commons.lang.time.DateUtils{
2 //自定义日期格式
3 public static final String SIMPLE_DATEFORMAT = "yyyy-MM-dd HH:mm:ss";
5 public static final String SIMPLE_DATEFORMAT_YMD = "yyyy-MM-dd";
6 //日期比较方法
7 public static int compareDate(Date first, Date second){
8 return first.compareTo(second);
10 //日期转string
11 public static String formatDateYMDHMS(Date date){
12 if(date==null){
13 return null;
14 }
15 return format(date,SIMPLE_DATEFORMAT);
16 }
17 //通用格式化
18 public static String format(Date date, String pattern) {
19 if (date == null) {
20 return null;
21 }
22 SimpleDateFormat format = new SimpleDateFormat(pattern);
23 return format.format(date);
24 }
1 public static void main(String[] args) {
2 int i = 0;
3 List<TimeTest> timeList = new ArrayList<>();
4 while (++i <= 5) {
5 TimeTest time = new TimeTest();
6 time.setTime(DateUtils.addMonths(DateUtils.now(), i));
7 timeList.add(time);
9 //插入一个空值
10 TimeTest time = new TimeTest();
11 timeList.add(time);
12 System.out.println("---------------初始值------------------");
13 timeList.forEach(o -> {
14 System.out.println(DateUtils.formatDateYMDHMS(o.getTime()));
15 });
16 System.out.println("---------------------------------------");
17 //下面有两种写法 推荐使用方法一
18 //代码解释: 将timeList流首先过滤时间不为空的,将需要比较的值转出map然后去重,最后取出最大值/最小值
19 //方法一 min(DateUtils::compareDate) 这种写法需要自己写工具类,且compareDate必须是static修饰
20 Date min = timeList.stream().filter(o -> o.getTime() != null).map(TimeTest::getTime).distinct().min(DateUtils::compareDate).get();
21 //方法二 max((e1, e2) -> e1.compareTo(e2))这种写法需要类里面含有比较方法
22 Date max = timeList.stream().filter(o -> o.getTime() != null).map(TimeTest::getTime).distinct().max((e1, e2) -> e1.compareTo(e2)).get();
23 System.out.println("min=" + DateUtils.formatDateYMDHMS(min));
24 System.out.println("max=" + DateUtils.formatDateYMDHMS(max));
1 ---------------初始值------------------
2 2019-09-09 14:35:53
3 2019-10-09 14:35:53
4 2019-11-09 14:35:53
5 2019-12-09 14:35:53
6 2020-01-09 14:35:53
7 null
8 ---------------------------------------
9 min=2019-09-09 14:35:53
10 max=2020-01-09 14:35:53
12 Process finished with exit code 0
