很实用的Android日期计算类

package com.utils.datecount;  import java.text.SimpleDateFormat; import java.util.Date; import java.util.GregorianCalendar;  public class DateCount {   /**   * datelevel 0为7天内，1为7到15天，2为15天以上   */  public static int datelevel = 0;  public static int positionweek = -1;  public static int position2week = -1;    /**   * 获取与今天时间差   * @param endTime   * @return   */  public static double countDate(String startTime) {      Date curDate = new Date(System.currentTimeMillis());// 获取当前时间   SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");// 输入日期的格式   Date date = null;    try {     date = simpleDateFormat.parse(startTime);     if (date == null) return 0;    } catch (java.text.ParseException e) {     return 0; //    e.printStackTrace();    }   GregorianCalendar cal1 = new GregorianCalendar();   GregorianCalendar cal2 = new GregorianCalendar();   cal1.setTime(date);   cal2.setTime(curDate);   double dayCount = (cal2.getTimeInMillis() - cal1.getTimeInMillis()) / (1000 * 3600 * 24);// 从间隔毫秒变成间隔天数   return dayCount;  } } 

package com.utils.tools;  import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date;  import android.text.TextUtils; import android.text.format.DateFormat;  /**  * 日期格式化工具类  *  * @author Harryxu  *  */ public class DateUtil {    public static Date convert2Date(String format, String dateStr) {   Date date = null;   try {    if (TextUtils.isEmpty(format)) format = "yyyy-MM-dd HH:mm:ss";    return new java.sql.Date(new SimpleDateFormat(format).parse(dateStr).getTime());   } catch (IllegalArgumentException e) {    e.printStackTrace();   } catch (Exception e) {    e.printStackTrace();   }   return date;  }   public static CharSequence formatDate(String format, String dateStr) {   Date date = null;   try {    date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(dateStr);   } catch (IllegalArgumentException e) {    e.printStackTrace();   } catch (Exception e) {    e.printStackTrace();   }   if (date == null) date = new Date();   if (TextUtils.isEmpty(format)) format = "yyyy-MM-dd";   return DateFormat.format(format, date);  }   /**   * 根据偏量值取得传入时间的前后天数   *   * @param date   * @param offset 时间偏量值   * @return   */  public static Date getNextPreDay(Date date, int offset) {   Calendar calendar = Calendar.getInstance();   calendar.setTime(date);   calendar.add(Calendar.DAY_OF_MONTH, offset);   date = calendar.getTime();   return date;  }    public static int getDays(Date date1, Date date2) {   Date kaishi = date1, jieshu = date2;   if (date1.compareTo(date2) > 0) {    kaishi = date2;    jieshu = date1;   }      long diff = jieshu.getTime() - kaishi.getTime();   float days = diff / 24f / 60 / 60 / 1000;   return (int) ((days - (int) days) >= 0 ? (days + 1) : days);  }    public static String addMinites( String time, int addminite){   SimpleDateFormat myFormatter = new SimpleDateFormat("HH:mm");    Calendar totime = Calendar.getInstance();   java.util.Date date = null;   try {    date = myFormatter.parse(time);   } catch (ParseException e) {    e.printStackTrace();   }   if (date == null) return null;   totime.setTime(date);   totime.add(Calendar.MINUTE, addminite);   date = totime.getTime();   return myFormatter.format(date);     } }