java calendar

**wdh** · March 8th, 2012, 02:41 PM

Ive made an IDCard class with a subclass called VisitorID.
The visitor ID is only valid for a certain date so ive created a method to check this. It was working for me but now it isnt and i cant see what ive done wrong.

Below is the method, when i call this method from my test class it returns ID card is not valid regardless of if its a correct or incorrect date. "dateValid" is the date string input when creating the Visitor ID card and is in the format dd/mm/yyyy.

public void isValid()
    {
        Calendar cal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
        if(sdf.format(cal.getTime()).equals(dateValid))
        {
            System.out.println("Visitor ID Card is Valid");
        }
        else
            System.out.println("Visitor ID Card is not valid");
    }

Any help appreciated

**Tjstretch** · March 8th, 2012, 03:37 PM

The problem is that your id card is going invalid within one millisecond. [Wow!] getTime returns the long in milliseconds from 1990. [I think], you should be checking that the end date of the id is greater than the current date.

In psuedo code

void isValid
  thetime = current time in milliseconds
  if thetime is greater than end time
    card is not valid
  else
    card is valid

Edit: from Calender getTime:
"Returns a Date object representing this Calendar's time value"

You are actually cheking the object that Calendar returns, which is not going to ever return true. You could use any of these methods [Depending on the rest of your program] for getting the time in milliseconds

Calendar.getTimeInMillis()
System.currentTimeMillis()
Calendar.getTime().getTime()

or to get the day that the Calendar 'cal' was created in this month:
cal.get(Calendar.DAY_OF_MONTH)
Year:
cal.get(Calendar.YEAR)
Whatever looks best to you.

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