Java8中处理日期时间

一时失言乱红尘 2023-06-28 04:53 36阅读 0赞

首先看一个对比

public class LocalDateDemo {
    
        public static void main(String[] args) {
                   
            //对比
            Calendar cal = Calendar.getInstance();
            System.out.println(cal.get(Calendar.YEAR));
            System.out.println(cal.get(Calendar.MONTH)); // 0 - 11
            System.out.println(cal.get(Calendar.DATE));
            System.out.println(cal.get(Calendar.HOUR_OF_DAY));
            System.out.println(cal.get(Calendar.MINUTE));
            System.out.println(cal.get(Calendar.SECOND));
            // Java 8
            LocalDateTime dt = LocalDateTime.now();
            System.out.println(dt.getYear());
            System.out.println(dt.getMonthValue()); // 1 - 12
            System.out.println(dt.getDayOfMonth());
            System.out.println(dt.getHour());
            System.out.println(dt.getMinute());
            System.out.println(dt.getSecond());
        }

输出结果：

2020
    0
    7
    14
    51
    44
    2020
    1
    7
    14
    51
    44

Java8中LocalDate的部分使用

/**
     * @program: java8_demo
     * @description: java8中处理日期和时间
     * @author: XZQ
     * @create: 2020-01-07 14:37
     **/
    public class LocalDateDemo {
    
        public static void main(String[] args) {
            LocalDate now = LocalDate.now();//当前日期
            System.out.println(now);//2020-01-07
            System.out.println(now.getYear());//获取年份 2020
            System.out.println(now.getMonthValue());//获取月份值 1
            System.out.println(now.getMonth());//获取月份 JANUARY
            System.out.println(now.getDayOfMonth());//获取日期 7
    
    
            LocalDate date = LocalDate.of(2018, 06, 20);//处理特定日期
            System.out.println(date);//2018-06-20
    
    
            System.out.println("----------------------");
            LocalTime localTime = LocalTime.now();//获取当前之间 只包含时间信息 无日期
            System.out.println(localTime);//14:45:24.562016700
    
    
            System.out.println("----------------------");
            LocalTime localTime1 = LocalTime.now();
            System.out.println("当前时间" + localTime);//当前时间14:45:24.562016700
            LocalTime localTime2 = localTime.plusHours(2);//增加2小时
            System.out.println("当前时间增加两小时" + localTime1);//当前时间增加两小时14:45:24.562016700
    
    
            LocalDate plusDate = now.plus(1, ChronoUnit.WEEKS);//一周后的日期
            System.out.println(plusDate);//2020-01-14
    
    
            LocalDate minusDate = now.minus(1, ChronoUnit.YEARS);//一年前的日期
            LocalDate plusDate1 = now.plus(1, ChronoUnit.YEARS);//一年后的日期
            System.out.println(minusDate);//2019-01-07
            System.out.println(plusDate1);//2021-01-07
    
            
            //Java 判断日期是早于还是晚于另一个日期
            LocalDate tomorrow = LocalDate.of(2018, 6, 20);
            if (tomorrow.isAfter(now)) {
                System.out.println("Tomorrow comes after today");
            }
            LocalDate yesterday = now.minus(1, ChronoUnit.DAYS);
            if (yesterday.isBefore(now)) {
                System.out.println("Yesterday is day before today");
            }
        }
    }

输出结果：

2020-01-07
    2020
    1
    JANUARY
    7
    2018-06-20
    ----------------------
    14:56:16.466634900
    ----------------------
    当前时间14:56:16.466634900
    当前时间增加两小时14:56:16.466634900
    2020-01-14
    2019-01-07
    2021-01-07
    Yesterday is day before today