Common Java Date comparison and date calculation methods summary _java

This article for everyone to share is the commonly used date comparison method, for future reference.

Warm-up: get current time

SimpleDateFormat df = new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss");//Set Date format
String nowdate = Df.format (new date ())//new date () to get current system time

Note: The landlord has always thought that the date type is not as arbitrary as the string type, so the following comparisons are all string-type date comparisons. If you really are that stubborn, OK, here's how to date to string:

SimpleDateFormat df = new SimpleDateFormat ("Yyyy-mm-dd HH:mm:ss");//Set Date format
String date = Df.format (time of date type);

1. Two string-type date comparison size

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 before DT2");
         return 1;
       } else if (Dt1.gettime () < Dt2.gettime ()) {
         System.out.println ("dt1 after DT2");
         return-1;
       } else {return
         0;
       }
     catch (Exception Exception) {
       exception.printstacktrace ();
     }
     return 0;
   }

2. Returns the number of days between two string dates

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. Returns the number of hours of the two string type date difference

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. Calculate the date of overlap between two periods

/** * Calculates the coincidence date of two dates * @param str1 start date 1 * @param str2 End date 1 * @param str3 start date 2 * @param STR4 End Date 2 * @re Turn * @throws Exception */public static map<string,object> Comparisonrq (String str1, String str2, string s
    TR3, 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";//coincident startdate = STR3;
      EndDate = str2; } if (Dt1.gettime () >=dt3.gettime () &&dt3.gettime () <=dt2.gettime () &&dt2.gettime () <=
        Dt4.gettime ()) {MESG = "F";//coincident startdate = str1;
      EndDate = str2; } if (dt3.geTtime () <=dt1.gettime () &&dt1.gettime () <=dt4.gettime () &&dt4.gettime ()) {
        MESG = "F";//coincident startdate = str1;
      EndDate = STR4; } if (Dt3.gettime () >=dt1.gettime () &&dt1.gettime () <=dt4.gettime () &&dt4.gettime () <=
        Dt2.gettime ()) {MESG = "F";//coincident 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;
 }

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