常用的java日期比较和日期计算方法小结

本文为大家分享的都是常用的日期之间的比较方法，供以后参考。

热身：获取当前时间

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//设置日期格式
String nowDate = df.format(new Date());// new Date()为获取当前系统时间

注：楼主一直以为date类型不如string类型随心所欲，所以下面的比较都是string类型的date进行比较。如果你真的真的就是那么倔强，ok，下面是date转string的方法：

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//设置日期格式
String date = df.format(Date类型的时间);

1.两个string类型的日期比较大小

public static int compare_date(String DATE1, String DATE2) {     DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");     try {       Date dt1 = df.parse(DATE1);       Date dt2 = df.parse(DATE2);       if (dt1.getTime() > dt2.getTime()) {         System.out.println("dt1 在dt2前");         return 1;       } else if (dt1.getTime() < dt2.getTime()) {         System.out.println("dt1在dt2后");         return -1;       } else {         return 0;       }     } catch (Exception exception) {       exception.printStackTrace();     }     return 0;   }

2.返回两个string类型日期之间相差的天数

public static int daysBetween(String smdate,String bdate){      SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");      Calendar cal = Calendar.getInstance();       long time1 = 0;     long time2 = 0;          try{       cal.setTime(sdf.parse(smdate));         time1 = cal.getTimeInMillis();         cal.setTime(sdf.parse(bdate));        time2 = cal.getTimeInMillis();      }catch(Exception e){       e.printStackTrace();     }     long between_days=(time2-time1)/(1000*3600*24);            return Integer.parseInt(String.valueOf(between_days));      }

3.返回两个string类型日期相差的小时数

public static int daysBetween2(String startTime, String endTime) {     SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH");      Calendar cal = Calendar.getInstance();       long time1 = 0;     long time2 = 0;          try{        cal.setTime(sdf.parse(startTime));          time1 = cal.getTimeInMillis();          cal.setTime(sdf.parse(endTime));         time2 = cal.getTimeInMillis();      }catch(Exception e){       e.printStackTrace();     }     long between_days=(time2-time1)/(1000*3600);             return Integer.parseInt(String.valueOf(between_days));      }

4.计算两段日期的重合日期

/**   * 计算两段日期的重合日期   * @param str1 开始日期1   * @param str2 结束日期1   * @param str3 开始日期2   * @param str4 结束日期2   * @return   * @throws Exception   */  public static Map<String,Object> comparisonRQ(String str1, String str2, String str3,      String str4) throws Exception {    String mesg = "";    DateFormat df = new SimpleDateFormat("yyyy-MM-dd");    String startdate = "";    String enddate = "";    try {      Date dt1 = df.parse(str1);      Date dt2 = df.parse(str2);      Date dt3 = df.parse(str3);      Date dt4 = df.parse(str4);      if (dt1.getTime()<=dt3.getTime()&&dt3.getTime()<=dt2.getTime()&&dt2.getTime()<=dt4.getTime()) {        mesg = "f";//重合        startdate = str3;        enddate = str2;      }      if (dt1.getTime()>=dt3.getTime()&&dt3.getTime()<=dt2.getTime()&&dt2.getTime()<=dt4.getTime()) {        mesg = "f";//重合        startdate = str1;        enddate = str2;      }            if (dt3.getTime()<=dt1.getTime()&&dt1.getTime()<=dt4.getTime()&&dt4.getTime()<=dt2.getTime()) {        mesg = "f";//重合        startdate = str1;        enddate = str4;      }      if (dt3.getTime()>=dt1.getTime()&&dt1.getTime()<=dt4.getTime()&&dt4.getTime()<=dt2.getTime()) {        mesg = "f";//重合        startdate = str3;        enddate = str4;      }            System.out.println(startdate+"----"+enddate);                }catch (ParseException e) {      e.printStackTrace();      throw new ParseException(e.getMessage(), 0);    }catch(Exception e){      e.printStackTrace();      throw new Exception(e);    }    Map<String,Object> map = new HashMap<String,Object>();    map.put("startdate", startdate);    map.put("enddate", enddate);    return map;  }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。