public static void main(String[] args) {

        DateTimeFormatter dateTimeFormatter=DateTimeFormatter.ofPattern("yy-MM-dd");
        LocalDate localDateTime=LocalDate.now();
        localDateTime.format(dateTimeFormatter);
        System.out.println(localDateTime);

        String time="2018-05-18 23:24:25";
        DateTimeFormatter dateTimeFormatter2=DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");//嚴格遵守大小寫
        LocalDateTime localDate=LocalDateTime.parse(time,dateTimeFormatter2);
        LocalDate localDate1=LocalDate.of(localDate.getYear(),localDate.getMonth(),localDate.getDayOfMonth());
        System.out.println(localDate1);//2018-05-18

}

　　說明: jdk1.8 嚴格區分LocalDate(日期) LocalDateTime(時間日期) LocalTime(時間)

JDK1.8 LocalDateTime 時間類與字符互轉