Java获取两个字符串日期的间隔天数

代码示例：

import java.time.*;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeParseException;

public class DateUtil {

    public static void main(String[] args) {
        long subDays = subDaysByDate("2021-10-01", "2021-11-20");
        System.out.println(subDays);

        long subDays2 = subDaysByDate2("2021-10-01", "2021-11-20");
        System.out.println(subDays2);

        long subDays3 = subDaysByDateTime("2021-10-01 10:00:00", "2021-11-20 11:00:00");
        System.out.println(subDays3);

    }

    private static final String DATE_PATTERN = "yyyy-MM-dd";
    private static final String DATETIME_PATTERN = "yyyy-MM-dd HH:mm:ss";

    /**
     * 获取两个日期相差的天数  方法一
     *
     * @param startDate 开始日期的字符串  yyyy-MM-dd
     * @param endDate   结束日期的字符串  yyyy-MM-dd
     * @return 相差天数，如果解析失败则返回-1
     **/
    public static long subDaysByDate(String startDate, String endDate) {
        long sub;
        try {
            DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(DATE_PATTERN);
            LocalDate start = LocalDate.parse(startDate, dateTimeFormatter);
            LocalDate end = LocalDate.parse(endDate, dateTimeFormatter);
            sub = Duration.between(LocalDateTime.of(start, LocalTime.of(0,0,0)),
                    LocalDateTime.of(end, LocalTime.of(0,0,0))).toDays();
        } catch (DateTimeParseException e) {
            sub = -1;
        }
        return sub;
    }


    /**
     * 获取两个日期相差的天数  方法二
     *
     * @param startDate 开始日期的字符串
     * @param endDate   结束日期的字符串
     * @return 相差天数，如果解析失败则返回-1
     **/
    public static long subDaysByDate2(String startDate, String endDate) {
        long sub;
        try {
            DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(DATE_PATTERN);
            LocalDate start = LocalDate.parse(startDate, dateTimeFormatter);
            LocalDate end = LocalDate.parse(endDate, dateTimeFormatter);

            sub = end.toEpochDay() - start.toEpochDay();
        } catch (DateTimeParseException e) {
            sub = -1;
        }
        return sub;
    }


    /**
     * 获取两个日期相差的天数,丢球最后的时间
     * @param startDate 开始日期的字符串
     * @param endDate   结束日期的字符串
     * @return 相差天数，如果解析失败则返回-1
     **/
    public static long subDaysByDateTime(String startDate, String endDate) {
        long sub;
        try {
            DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(DATETIME_PATTERN);
            LocalDateTime start = LocalDateTime.parse(startDate, dateTimeFormatter);
            LocalDateTime end = LocalDateTime.parse(endDate, dateTimeFormatter);
            sub = Duration.between(start, end).toDays();
        } catch (DateTimeParseException e) {
            sub = -1;
        }
        return sub;
    }

}