java如何获取两个日期的时间差

 @SuppressLint("SimpleDateFormat")
 SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 df.setTimeZone(TimeZone.getTimeZone("GMT+08"));// 这里一定要设置GMT时区
 String currentTime = df.format(new Date());
 Date date1 = MyDateUtil.parseDate(trainBeginTime.replace("T"," "), "yyyy-MM-dd HH:mm:ss");
 Date date2 = MyDateUtil.parseDate(currentTime, "yyyy-MM-dd HH:mm:ss");
 // 获取相差的天数
 Calendar calendar = Calendar.getInstance();
 calendar.setTime(date1);
 long timeInMillis1 = calendar.getTimeInMillis();
 calendar.setTime(date2);
 long timeInMillis2 = calendar.getTimeInMillis();
 long betweenDays = ((timeInMillis2 - timeInMillis1) / (1000L*3600L*24L))+2;
textView.setText("时间相差"+betweenDays+"天");

import android.os.Build;
import androidx.annotation.RequiresApi;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.Calendar;
import java.util.Date;

/**
 * Description: 日期工具类
 */
public class MyDateUtil {
 /**
 * 将指定的日期字符串转换成日期
 * @param dateStr 日期字符串
 * @param pattern 格式
 * @return 日期对象
 */
 public static Date parseDate(String dateStr, String pattern)
 {
 SimpleDateFormat sdf = new SimpleDateFormat(pattern);
 Date date;
 try {
  date = sdf.parse(dateStr);
 } catch (ParseException e) {
  throw new RuntimeException("日期转化错误");
 }
 return date;
 }
 /**
 * 将指定的日期格式化成指定的日期字符串
 * @param date 日期对象
 * @param pattern 格式
 * @return 格式化后的日期字符串
 */
 public static String dateFormate(Date date, String pattern)
 {
 SimpleDateFormat sdf = new SimpleDateFormat(pattern);
 String dateStr;
 if(date == null)
 {
  return "";
 }
 dateStr = sdf.format(date);
 return dateStr;
 }
 /**
 * 查询指定日期前后指定的天数
 * @param date 日期对象
 * @param days 天数
 * @return 日期对象
 */
 public static Date incr(Date date, int days)
 {
 if (date == null){
  return null;
 }
 Calendar calendar = Calendar.getInstance();
 calendar.setTime(date);
 calendar.add(Calendar.DAY_OF_MONTH, days);
 return calendar.getTime();
 }

 /**
 * 将LocalDate日期转化成Date
 * @param localDate LocalDate对象
 * @return Date对象
 */
 @RequiresApi(api = Build.VERSION_CODES.O)
 public static Date localDateToDate(LocalDate localDate)
 {
 if (localDate == null)
 {
  return null;
 }
 ZoneId zoneId = ZoneId.systemDefault();
 ZonedDateTime zonedDateTime = localDate.atStartOfDay(zoneId);
 Date date = Date.from(zonedDateTime.toInstant());
 return date;
 }
 /**
 * 将Date转成LocalDate对象
 * @param date Date对象
 * @return LocalDate对象
 */
 @RequiresApi(api = Build.VERSION_CODES.O)
 public static LocalDate dateToLocalDate(Date date)
 {
 if (date == null)
 {
  return null;
 }
 ZoneId zoneId = ZoneId.systemDefault();
 Instant instant = date.toInstant();
 LocalDate localDate = instant.atZone(zoneId).toLocalDate();
 return localDate;
 }
}