3 ms·

A quick google would have found: new SimpleDateFormat("HH MM YYYY").format(new Date()); new SimpleDateFormat("HH MM YYYY").parse("17 02 2014");

by Bgill 13y ago

bane 13y ago
Well geez, there you go. My google fu obviously failed me, I definitely did not come across this yet another Date Formatting library in the Java Standard Library. Why isn't all this garbage just bundled into the Date class? It seems to me that among the many things somebody might want to do on a date, converting the String representation might be one of them. okay here's what I'm talking about. From the API docs on Date toGMTString() - *Deprecated.* As of JDK version 1.1, replaced by DateFormat.format(Date date), using a GMT TimeZone. toLocaleString() - *Deprecated.* As of JDK version 1.1, replaced by DateFormat.format(Date date). toString() - Converts this Date object to a String of the form: dow mon dd hh:mm:ss zzz yyyy All either deprecated or useless (dow mon dd hh:mm:ss zzz yyyy? really?). And the documentation doesn't point to the better classes to do what I want. Okay, so what's a DateFormat? DateFormat is an abstract class for date/time formatting subclasses which formats and parses dates or time in a language-independent manner. Okay that sounds promising, of course they're admitting they don't have the concept of a "Date Format" object type since it's all just static stuff, so shouldn't all this just be in the Date class? That feels weird. Wait there's a DateFormatter, that sounds promising, it's all verby sounding. DateFormatter is an InternationalFormatter that does its formatting by way of an instance of java.text.DateFormat. Well what the hell is an InternationalFormatter? And down the rabbit hole I went. I did eventually figure it out. But it was so inelegant and stupid I felt ashamed to have it in my code. If I had read one more line in the DateFormatter doc I suppose I could have found SimpleDateFormat, but the bizarre complexity about converting formats was already so mind bendingly dumb. This is stupid and obtuse design, overly parsing the problem and unnecessarily separating what should be connected pieces of the puzzle. Solution (needs revision, but this would be a useful point to start a discussion): Classes Date - a representation of a specific date and time down to millionths of a second resolution methods: add, sub Dates - returns Duration add,sub Duration, returns Dates one of the constructors takes a String that ostensibly contains a Date of some sort, and a format String to parse it, throws exception if the date isn't valid setOutPutFormat - takes a Format string and the next call toString() emits on that format. all the get, set hour minute day year methods so you can pick it apart change pieces as you want setOutPutCalendar - changes the Date to whatever recognized calendar system (Chinese, Arabic, Hebrew, etc.), setOutPutFormat is context aware of this all the timezone stuff after and before get/set 2 digit year Date comparison methods like isBefore(Date) to see if another Date object is before or after this one Done. All of Date, DateFormat and SimpleDateFormat is there, problems solved Duration - an representation of a time Duration (6 days, 7 minutes, 14 second), and since all time intervals are durations, that's it. Methods: Constructor can be an ISO 8601 String for Duration or two Date objects representing the beginning and end of a duration. Since Date objects should have their own timezone and locals, the magic black box of this class should figure out the duration for me. It's not my problem to sort this out. If the begin and end dates produce a negative duration that's cool because now I have a countdown. Duration comparison methods, like isWithin(Duration) to check if another duration object is within this one or isWithin(Date) to see if a Date is within the duration or isLongerthan(Duration) Duration math like add/subtract other durations from the begin and end of the Duration Done.
- barrkel 13y ago
  Most of what you want sounds like DateTime and TimeSpan from .net. However Joda does a lot more, like taking into account the various historical, political changes in time zone, and the distinction between a duration between two human-understandable semantic times, versus a duration as a fixed span of time.
  - bane 13y ago
    I'm probably looking at the issue too simply, but shouldn't all that be abstracted away into the library, with maybe some notes on particularly weird cases? I'm also not sure I understand the distinction between the two durations, if I set a startDate object up on the Islamic Tabular Fatimid calendar and say it's year 14 and endDate is some pre-reformation Julian calendar and say it's year 231, shouldn't the Duration class be able to figure out a fixed span of time from that? I really could care less how it does it, just that the right number of years, months and days fall out of it. Or if I just want to create the object with some defined span, they're the same thing.
    - kbolino 13y ago
      Given a date, how do you obtain a new date equal to the same month and day of month in the following year? You can't do that consistently with a duration measured in milliseconds or nanoseconds. Instead, you need a more abstract representation of time, something akin to "increment only the year field of a date". That's what Periods are for.

A quick google would have found: new SimpleDateFormat("HH MM YYYY").format(new Date()); new SimpleDateFormat("HH MM YYYY").parse("17 02 2014");

by Bgill 13y ago

A quick google would have found: new SimpleDateFormat("HH MM YYYY").format(new Date()); new SimpleDateFormat("HH MM YYYY").parse("17 02 2014");

bane 13y ago

Well geez, there you go. My google fu obviously failed me, I definitely did not come across this yet another Date Formatting library in the Java Standard Library. Why isn't all this garbage just bundled into the Date class? It seems to me that among the many things somebody might want to do on a date, converting the String representation might be one of them. okay here's what I'm talking about. From the API docs on Date toGMTString() - *Deprecated.* As of JDK version 1.1, replaced by DateFormat.format(Date date), using a GMT TimeZone. toLocaleString() - *Deprecated.* As of JDK version 1.1, replaced by DateFormat.format(Date date). toString() - Converts this Date object to a String of the form: dow mon dd hh:mm:ss zzz yyyy All either deprecated or useless (dow mon dd hh:mm:ss zzz yyyy? really?). And the documentation doesn't point to the better classes to do what I want. Okay, so what's a DateFormat? DateFormat is an abstract class for date/time formatting subclasses which formats and parses dates or time in a language-independent manner. Okay that sounds promising, of course they're admitting they don't have the concept of a "Date Format" object type since it's all just static stuff, so shouldn't all this just be in the Date class? That feels weird. Wait there's a DateFormatter, that sounds promising, it's all verby sounding. DateFormatter is an InternationalFormatter that does its formatting by way of an instance of java.text.DateFormat. Well what the hell is an InternationalFormatter? And down the rabbit hole I went. I did eventually figure it out. But it was so inelegant and stupid I felt ashamed to have it in my code. If I had read one more line in the DateFormatter doc I suppose I could have found SimpleDateFormat, but the bizarre complexity about converting formats was already so mind bendingly dumb. This is stupid and obtuse design, overly parsing the problem and unnecessarily separating what should be connected pieces of the puzzle. Solution (needs revision, but this would be a useful point to start a discussion): Classes Date - a representation of a specific date and time down to millionths of a second resolution methods: add, sub Dates - returns Duration add,sub Duration, returns Dates one of the constructors takes a String that ostensibly contains a Date of some sort, and a format String to parse it, throws exception if the date isn't valid setOutPutFormat - takes a Format string and the next call toString() emits on that format. all the get, set hour minute day year methods so you can pick it apart change pieces as you want setOutPutCalendar - changes the Date to whatever recognized calendar system (Chinese, Arabic, Hebrew, etc.), setOutPutFormat is context aware of this all the timezone stuff after and before get/set 2 digit year Date comparison methods like isBefore(Date) to see if another Date object is before or after this one Done. All of Date, DateFormat and SimpleDateFormat is there, problems solved Duration - an representation of a time Duration (6 days, 7 minutes, 14 second), and since all time intervals are durations, that's it. Methods: Constructor can be an ISO 8601 String for Duration or two Date objects representing the beginning and end of a duration. Since Date objects should have their own timezone and locals, the magic black box of this class should figure out the duration for me. It's not my problem to sort this out. If the begin and end dates produce a negative duration that's cool because now I have a countdown. Duration comparison methods, like isWithin(Duration) to check if another duration object is within this one or isWithin(Date) to see if a Date is within the duration or isLongerthan(Duration) Duration math like add/subtract other durations from the begin and end of the Duration Done.

barrkel 13y ago
Most of what you want sounds like DateTime and TimeSpan from .net. However Joda does a lot more, like taking into account the various historical, political changes in time zone, and the distinction between a duration between two human-understandable semantic times, versus a duration as a fixed span of time.
- bane 13y ago
  I'm probably looking at the issue too simply, but shouldn't all that be abstracted away into the library, with maybe some notes on particularly weird cases? I'm also not sure I understand the distinction between the two durations, if I set a startDate object up on the Islamic Tabular Fatimid calendar and say it's year 14 and endDate is some pre-reformation Julian calendar and say it's year 231, shouldn't the Duration class be able to figure out a fixed span of time from that? I really could care less how it does it, just that the right number of years, months and days fall out of it. Or if I just want to create the object with some defined span, they're the same thing.
  - kbolino 13y ago
    Given a date, how do you obtain a new date equal to the same month and day of month in the following year? You can't do that consistently with a duration measured in milliseconds or nanoseconds. Instead, you need a more abstract representation of time, something akin to "increment only the year field of a date". That's what Periods are for.