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Thursday, February 16, 2017

Calculate Time Difference Between Two Clocks in String Format

The other day I was looking for calculating the time difference between two clocks in String format. I could find a better solution, so I wrote a custom one. Take a look at the Java Code below:

   1:  public static String calTimeDifference(String startHour, 
       String startMin, String endHour, String endMin){
   2:   
   3:  String total = "0";     
   4:   
   5:  if (!StringUtils.isEmpty(startHour) && 
       !StringUtils.isEmpty(startMin) && 
       !StringUtils.isEmpty(endHour) && 
       !StringUtils.isEmpty(endMin){
   6:   
   7:   int stHr = Integer.parseInt(startHour) * 60 ;
   8:   
   9:   int stMn = Integer.parseInt(startMin);
  10:   
  11:   int enHr = Integer.parseInt(endHour) * 60 ;
  12:   
  13:   int enMn = Integer.parseInt(endMin);
  14:   
  15:   int startTime = stHr + stMn;
  16:   
  17:   int endTime = enHr + enMn;
  18:   
  19:    if (endTime > startTime){
  20:   
  21:     int durationHr = (endTime - startTime)/60;
  22:   
  23:     int durationMn = (endTime - startTime)%60;
  24:   
  25:     total = Integer.toString(durationHr) + " Hr and "
         + Integer.toString(durationMn) + " Min" ;
  26:   
  27:      }
  28:   
  29:     else{
  30:   
  31:      total = "Ending Time cannot be before Starting Time";
  32:   
  33:      }
  34:   
  35:    }       
  36:   
  37:   return total;
  38:   
  39:  }


The above code should work as long as you keep in mind the pre and post conditions.

Pre-Condition:
This function assumes that all four parameters are present so if even one of them is missing it will return zero.

Post-Condition:
This function will also make sure that the ending time cannot be before the starting time if it is it will return the error message.

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