Why can't I catch an exception?

[glhansen]

I've been converting between dates and strings with the form "03/18/09". The code splits the string at the /'s, converts to integers, and sticks it in an instance of Calendar. There are a few different ways for that to go wrong: non-numbers, not enough numbers, and not a valid date. So I've been using try/catch blocks so that parseInt() and Calendar.set() can throw whatever they want, and I just throw my own NumberFormatException if I don't have enough numbers. The exception handling is to refocus on the date field with the text selected, so the user can try again. And that works fine with non-numbers or too few numbers.

But I get runtime errors vomiting on the screen when I try an invalid date, even from a try/catch block. That part of the code (not including diagnostic System.out.println()s) looks something like this.

		try {
			DateString.StringToCal(ds, Database.date);
		}
		catch (Exception ex) {
			dateText.requestFocus();
		}

I thought that would catch any exception that can be thrown. What's up with that?

[masijade]

try catching Throwable, but I have the feeling that something is being thrown in a spot where you are not expecting it, and so not catching it.

P.S., what is wrong with SimpleDateFormat?

SimpleDateFormat (Java Platform SE 6)

And don't forget about setting

sdf.setLenient(false);

[toadaly]

If an Exception is being thrown in a different thread, a try/catch will not help. You need to thoroughly check for invalid dates before submitting them to your database to prevent this.

[glhansen]

I didn't use a SimpleDateFormat because I couldn't figure it out, couldn't figure out how to use it to set a Calendar. I think I've figured it out now, setTime() will set the date, too. But when I parse a date, set the calendar, and get it back out, like

		SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yy");
		Date d = new Date();
		try {
			d = sdf.parse("03/16/09");
			c.setTime(d);
		}
		catch (Exception e) {System.out.println("Error -- " + e.toString()); }
		System.out.println("Month: " + c.get(Calendar.MONTH));
		System.out.println("Day: " + c.get(Calendar.DAY_OF_MONTH));
		System.out.println("Year: " + c.get(Calendar.YEAR));

is it normal for the month I get out to be one less than the month I get in? If I put "03/16/09" in, I get

Month: 2
Day: 16
Year: 2009

out.

[masijade]

Month is a zero based field (i.e. January is 0 not one). Use another SimpleDateFormat (or the same one) to format the output.

[glhansen]

I think I've figured it out. But I saw so many deprecated Date constructors I didn't know if I was even supposed to be using Dates any more, I wasn't sure if I should be storing my dates as Dates or Calendars, I didn't realize that

StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition pos)

could take a single parameter and fill a String, didn't find code examples that made sense to me... so much of this just isn't obvious to someone who's been working with Java for two weeks.