Java Patterns

[vijay shanker]

Hi Group,

I am working on a project in which i need to date date and time values from input text.

I am planning to use Pattern class for this.

my questions are
- how feasible is to use this class for this operation
- Is there any other option i can look forward for.

For more example i made this pattern to read simple time input

  
\\d{1,2}(:)\\d{1,2}\\s{0,1}(am|AM|pm|PM){0,1}

although it is working well. but this is not all the case. if user enters 06:30a, or 06:30aM, then i am screwed.

what should i do for this. What will be the best approach for this project.

[Maneesh Godbole]

Check out Simple Date Format

[Campbell Ritchie]

Since aM is not a recognised abbreviation (it should always be am not AM) you should be throwing an Exception for erroneous input.

[vijay shanker]

Maneesh Godbole wrote:Check out Simple Date Format

ya i looked in to this class too; But i am not able to get any clear idea about how should i proceed.

Please help me out.

[Maneesh Godbole]

Recommended reading http://java.sun.com/docs/books/tutorial/uiswing/components/spinner.html , especially the formatting part

[Michael Angstadt]

vijay shanker wrote:

Maneesh Godbole wrote:Check out Simple Date Format

ya i looked in to this class too; But i am not able to get any clear idea about how should i proceed.

Please help me out.

You use the SimpleDateFormat class to take a String and convert it into a Date object. The Date object holds time information too, not just date information. Once you have your Date object, you can use the Calendar class to extract the time information out of it.

DateFormat df = new SimpleDateFormat("format string");
Date d = df.parse("06:45am");
Calendar c = Calendar.getInstance();
c.setTime(d);
int hour = c.get(Calendar.HOUR);
int minute = c.get(Calendar.MINUTE);
int amPm = c.get(Calendar.AM_PM);

[vijay shanker]

There is something missing in my requirement and your suggestions.

1. i am not aware of what format user enters to input time values. It can be like i said 9:30PM or 9:30 PM or 9:30 pm or 9:30pm or 9:30p.
2. i see SimpleDateFormat supports to fetch time formats from any input text. but not able to identify how to set variable format like i have given above.
3. Throwing exception is not my motive. I want to perceive what any user has given in the input. and i want it to be correctively perceived,

[Michael Angstadt]

vijay shanker wrote:i am not aware of what format user enters to input time values.

As with any input you get from the user, you should (1) clean it so that it matches the format you're looking for, (2) force the user to input it in a specific way, or (3) use a combination of both. Maybe something like this:

String input = "6:30 Pm";
input = input.replaceAll(" ", ""); //remove spaces
input = input.toLowerCase(); //uniform case
if (input.matches("\\d{1,2}(:)\\d{2}(am|pm){0,1}")){
  //use DateFormat to parse the time
}

[Garrett Rowe]

Campbell Ritchie wrote:Since aM is not a recognised abbreviation (it should always be am not AM) you should be throwing an Exception for erroneous input.

I have not seen a reference that agrees with this. That must be unique to the UK (or is it U.K. ). http://en.wikipedia.org/wiki/12-hour_clock I bet you also put your curly braces in the wrong place don't you.

[Campbell Ritchie]

I've never seen capitals for am or pm. But the 12-hours clock is now largely restricted to informal uses.

[David Newton]

I see capitals for AM/PM all the time, and most people are informal and use a 12-hour clock, at least in the US, if they're not in the military.

[Campbell Ritchie]

I concede defeat.

[Joanne Neal]

Javaranch uses PM in the posting times at the top of each individual message.
I think there may be a bug though because it doesn't change to AM when I post a message in the mornings.

Edit - just noticed it only appears in other people's posts - not in my posts.

[David Newton]

What doesn't appear? I see AM/PM in your posts :)

[Joanne Neal]

That's strange. The PM didn't appear in my post when I viewed the thread straight after posting, but it does appear now.
Edit - ignore that. i wasn't logged in when I saw the PM in my post. D'oh.

Anyway, enough of the serious stuff. Which of my posts do you see AM in ?

Edit2 - apologies to vijay for hijacking his post. Probably should stop this now as I don't think he has got an answer yet.