Hi ha dues classes per donar format a les dates a Java: DateFormat i SimpleDateFormat.

La classe java.text.DateFormat proporciona diversos mètodes per formatar i analitzar la data i l'hora en java de manera independent de l'idioma. La classe DateFormat és una classe abstracta. java.text. El format és la classe principal i java.text.SimpleDateFormat és la subclasse de la classe java.text.DateFormat.

A Java, convertir la data en la cadena s'anomena formatació i viceversa. En altres paraules, format significa data a cadena, i anàlisi significa cadena fins a la data .

Camps java.text.DateFormat

 protected Calendar calendar protected NumberFormat numberFormat public static final int ERA_FIELD public static final int YEAR_FIELD public static final int MONTH_FIELD public static final int DATE_FIELD public static final int HOUR_OF_DAY1_FIELD public static final int HOUR_OF_DAY0_FIELD public static final int MINUTE_FIELD public static final int SECOND_FIELD public static final int MILLISECOND_FIELD public static final int DAY_OF_WEEK_FIELD public static final int DAY_OF_YEAR_FIELD public static final int DAY_OF_WEEK_IN_MONTH_FIELD public static final int WEEK_OF_YEAR_FIELD public static final int WEEK_OF_MONTH_FIELD public static final int AM_PM_FIELD public static final int HOUR1_FIELD public static final int HOUR0_FIELD public static final int TIMEZONE_FIELD public static final int FULL public static final int LONG public static final int MEDIUM public static final int SHORT public static final int DEFAULT 

java.text.DateFormat Mètodes

Exemple de format de data de Java: data a cadena

Vegem un exemple senzill format de data i hora en Java utilitzant la classe java.text.DateFormat.

Nom de l'arxiu: DateFormatExample.java

 import java.text.DateFormat; import java.util.Date; public class DateFormatExample { public static void main(String[] args) { Date currentDate = new Date(); System.out.println('Current Date: '+currentDate); String dateToStr = DateFormat.getInstance().format(currentDate); System.out.println('Date Format using getInstance(): '+dateToStr); } } 

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str a int

Current Date: Tue Mar 31 14:37:23 IST 2015 Date Format using getInstance(): 31/3/15 2:37 PM 

Vegem l'exemple complet format de data i hora en Java utilitzant la classe java.text.DateFormat.

Nom de l'arxiu: DateFormatExample2.java

 import java.text.DateFormat; import java.util.Date; public class DateFormatExample2 { public static void main(String[] args) { Date currentDate = new Date(); System.out.println('Current Date: '+currentDate); String dateToStr = DateFormat.getInstance().format(currentDate); System.out.println('Date Format using getInstance(): '+dateToStr); dateToStr = DateFormat.getDateInstance().format(currentDate); System.out.println('Date Format using getDateInstance(): '+dateToStr); dateToStr = DateFormat.getTimeInstance().format(currentDate); System.out.println('Date Format using getTimeInstance(): '+dateToStr); dateToStr = DateFormat.getDateTimeInstance().format(currentDate); System.out.println('Date Format using getDateTimeInstance(): '+dateToStr); dateToStr = DateFormat.getTimeInstance(DateFormat.SHORT).format(currentDate); System.out.println('Date Format using getTimeInstance(DateFormat.SHORT): '+dateToStr); dateToStr = DateFormat.getTimeInstance(DateFormat.MEDIUM).format(currentDate); System.out.println('Date Format using getTimeInstance(DateFormat.MEDIUM): '+dateToStr); dateToStr = DateFormat.getTimeInstance(DateFormat.LONG).format(currentDate); System.out.println('Date Format using getTimeInstance(DateFormat.LONG): '+dateToStr); dateToStr = DateFormat.getDateTimeInstance(DateFormat.LONG,DateFormat.SHORT).format(currentDate); System.out.println('Date Format using getDateTimeInstance(DateFormat.LONG,DateFormat.SHORT): '+dateToStr); } } 

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Current Date: Tue Mar 31 14:37:23 IST 2015 Date Format using getInstance(): 31/3/15 2:37 PM Date Format using getDateInstance(): 31 Mar, 2015 Date Format using getTimeInstance(): 2:37:23 PM Date Format using getDateTimeInstance(): 31 Mar, 2015 2:37:23 PM Date Format using getTimeInstance(DateFormat.SHORT): 2:37 PM Date Format using getTimeInstance(DateFormat.MEDIUM): 2:37:23 PM Date Format using getTimeInstance(DateFormat.LONG): 2:37:23 PM IST Date Format using getDateTimeInstance(DateFormat.LONG,DateFormat.SHORT): 31 March, 2015 2:37 PM 

Exemple Java DataFormat: String to Date

Vegem un exemple senzill convertir la cadena en data utilitzant la classe java.text.DateFormat.

Nom de l'arxiu: DateFormatExample3.java

 import java.text.DateFormat; import java.util.Date; public class DateFormatExample3 { public static void main(String[] args)throws Exception { Date d = DateFormat.getDateInstance().parse('31 Mar, 2015'); System.out.println('Date is: '+d); } } 

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doble en java

 Date is: Tue Mar 31 00:00:00 IST 2015 

Exemple de format de data de Java: getTimeInstance (estil int, configuració regional)

Vegem el funcionament del mètode getTimeInstance (estil int, Locale locale).

Nom de l'arxiu: GetTimeInstanceExample.java

 // important important statements import java.util.Date; import java.util.Locale; import java.text.DateFormat; public class GetTimeInstanceExample { // main method public static void main(String argvs[]) throws Exception { // locale is French here. Locale lcl = Locale.FRENCH; // creating an object of the class Date Date d = new Date(); // getting the instance by invoking the getTimeInstance(int, Locale) method DateFormat dFormat = DateFormat.getTimeInstance(DateFormat.SHORT, lcl); String str = dFormat.format(d); System.out.println(str); } } 

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 13:12 

Exemple Java DataFormat: getDateInstance (estil int)

Vegem el funcionament del mètode getDateInstance (estil int).

Nom de l'arxiu: GetDateInstanceExample.java

 // important important statements import java.util.Date; import java.util.Locale; import java.text.DateFormat; public class GetDateInstanceExample { // main method public static void main(String argvs[]) throws Exception { // creating an object of the class Date Date d = new Date(); // getting the instance by invoking the getDateInstance(int) method // here default locale is used DateFormat dFormat = DateFormat.getDateInstance(DateFormat.SHORT); String str = dFormat.format(d); System.out.println(str); } } 

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 12/2/21 

Exemple de format de data de Java: getDateInstance (estil int, configuració regional)

Vegem el funcionament del mètode getDateInstance(estil int, Locale locale).

Nom de l'arxiu: GetDateInstanceExample1.java

negació matemàtiques discretes

 // important important statements import java.util.Date; import java.util.Locale; import java.text.DateFormat; public class GetDateInstanceExample1 { // main method public static void main(String argvs[]) throws Exception { // locale is French here. Locale lcl = Locale.FRENCH; // creating an object of the class Date Date d = new Date(); // getting the instance by invoking the getDateInstance(int, Locale) method DateFormat dFormat = DateFormat.getDateInstance(DateFormat.SHORT, lcl); String str = dFormat.format(d); System.out.println(str); } } 

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 02/12/2021 

Exemple de format de data Java: getDateTimeInstance(int dataStyle, int timeStyle, Locale locale)

Vegem el funcionament del mètode getDateTimeInstance(int dateStyle, int timeStyle, Locale locale).

Nom de l'arxiu: GetDateTimeInstanceExample.java

 // important important statements import java.util.Date; import java.util.Locale; import java.text.DateFormat; public class GetDateTimeInstanceExample { // main method public static void main(String argvs[]) throws Exception { // locale is French here. Locale lcl = Locale.FRENCH; // creating an object of the class Date Date d = new Date(); // getting the instance by invoking the getDateTimeInstance(int, int, Locale) method DateFormat dFormat = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.LONG, lcl); String str = dFormat.format(d); System.out.println(str); } } 

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 02/12/2021 14:16:34 GMT 

Exemple de format de data de Java: getCalender()

Vegem el funcionament del mètode getCalender().

Nom de l'arxiu: GetCalenderExample.java

 // important import statements import java.util.Date; import java.text.DateFormat; import java.text.*; public class GetCalenderExample { // main method public static void main(String argvs[]) throws Exception { // getting the instance DateFormat dFormat = DateFormat.getDateTimeInstance(); // invoking the method getCalender(); System.out.println(dFormat.getCalendar()); } } 

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La cadena conté java

 java.util.GregorianCalendar[time = -886152493222, areFieldsSet = true, areAllFieldsSet = true, lenient = true, zone = sun.util.calendar.ZoneInfo[id = 'GMT', offset=0, dstSavings = 0, useDaylight = false, transitions = 0, lastRule = null], firstDayOfWeek = 1, minimalDaysInFirstWeek = 1,ERA = 1, YEAR = 1941, MONTH = 11, WEEK_OF_YEAR = 49, WEEK_OF_MONTH = 1, DAY_OF_MONTH = 2, DAY_OF_YEAR = 336, DAY_OF_WEEK = 3, DAY_OF_WEEK_IN_MONTH = 1, AM_PM = 1, HOUR = 2, HOUR_OF_DAY = 14, MINUTE = 31, SECOND = 46, MILLISECOND = 778, ZONE_OFFSET = 0, DST_OFFSET = 0] 

Exemple Java DataFormat: getNumberFormat()

Vegem el funcionament del mètode getNumberFormat().

Nom de l'arxiu: GetNumberFormatExample.java

 // important import statements import java.text.NumberFormat; import java.text.DateFormat; public class DateFormatDemo { // main method public static void main(String[] argvs) { // getting the instance by invoking the getTimeInstance() method DateFormat dFormat = DateFormat.getTimeInstance(DateFormat.SHORT); // invoking the method getNumberFormat() NumberFormat numFormat = dFormat.getNumberFormat(); System.out.println('The format is: ' + numFormat); } } 

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 The format is: java.text.DecimalFormat@674dc