The Java Tutorials have been written for JDK 8.Java教程是为JDK 8编写的。Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.本页中描述的示例和实践没有利用后续版本中引入的改进，并且可能使用不再可用的技术。See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.有关Java SE 9及其后续版本中更新的语言特性的摘要，请参阅Java语言更改。
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.有关所有JDK版本的新功能、增强功能以及已删除或不推荐的选项的信息，请参阅JDK发行说明。
This tutorial does not discuss the java.time.chrono package in any detail. However, it might be useful to know that this package provides several predefined chronologies that are not ISO-based, such as Japanese, Hijrah, Minguo, and Thai Buddhist. You can also use this package to create your own chronology.
This section shows you how to convert between an ISO-based date and a date in one of the other predefined chronologies.
You can convert an ISO-based date to a date in another chronology by using the from(TemporalAccessor) method, such as JapaneseDate.from(TemporalAccessor). This method throws a DateTimeException if it is unable to convert the date to a valid instance. The following code converts a LocalDateTime instance to several predefined non-ISO calendar dates:
LocalDateTime date = LocalDateTime.of(2013, Month.JULY, 20, 19, 30); JapaneseDate jdate = JapaneseDate.from(date); HijrahDate hdate = HijrahDate.from(date); MinguoDate mdate = MinguoDate.from(date); ThaiBuddhistDate tdate = ThaiBuddhistDate.from(date);
The StringConverter example converts from a LocalDate to a ChronoLocalDate to a String and back. The toString method takes an instance of LocalDate and a Chronology and returns the converted string by using the provided Chronology. The DateTimeFormatterBuilder is used to build a string that can be used for printing the date:
/**
* Converts a LocalDate (ISO) value to a ChronoLocalDate date
* using the provided Chronology, and then formats the
* ChronoLocalDate to a String using a DateTimeFormatter with a
* SHORT pattern based on the Chronology and the current Locale.
*
* @param localDate - the ISO date to convert and format.
* @param chrono - an optional Chronology. If null, then IsoChronology is used.
*/
public static String toString(LocalDate localDate, Chronology chrono) {
if (localDate != null) {
Locale locale = Locale.getDefault(Locale.Category.FORMAT);
ChronoLocalDate cDate;
if (chrono == null) {
chrono = IsoChronology.INSTANCE;
}
try {
cDate = chrono.date(localDate);
} catch (DateTimeException ex) {
System.err.println(ex);
chrono = IsoChronology.INSTANCE;
cDate = localDate;
}
DateTimeFormatter dateFormatter =
DateTimeFormatter.ofLocalizedDate(FormatStyle.SHORT)
.withLocale(locale)
.withChronology(chrono)
.withDecimalStyle(DecimalStyle.of(locale));
String pattern = "M/d/yyyy GGGGG";
return dateFormatter.format(cDate);
} else {
return "";
}
}When the method is invoked with the following date for the predefined chronologies:
LocalDate date = LocalDate.of(1996, Month.OCTOBER, 29);
System.out.printf("%s%n",
StringConverter.toString(date, JapaneseChronology.INSTANCE));
System.out.printf("%s%n",
StringConverter.toString(date, MinguoChronology.INSTANCE));
System.out.printf("%s%n",
StringConverter.toString(date, ThaiBuddhistChronology.INSTANCE));
System.out.printf("%s%n",
StringConverter.toString(date, HijrahChronology.INSTANCE));The output looks like this:
10/29/0008 H 10/29/0085 1 10/29/2539 B.E. 6/16/1417 1
You can convert from a non-ISO date to a LocalDate instance using the static LocalDate.from method, as shown in the following example:
LocalDate date = LocalDate.from(JapaneseDate.now());
Other temporal-based classes also provide this method, which throws a DateTimeException if the date cannot be converted.
The fromString method, from the StringConverter example, parses a String containing a non-ISO date and returns a LocalDate instance.
/**
* Parses a String to a ChronoLocalDate using a DateTimeFormatter
* with a short pattern based on the current Locale and the
* provided Chronology, then converts this to a LocalDate (ISO)
* value.
*
* @param text - the input date text in the SHORT format expected
* for the Chronology and the current Locale.
*
* @param chrono - an optional Chronology. If null, then IsoChronology
* is used.
*/
public static LocalDate fromString(String text, Chronology chrono) {
if (text != null && !text.isEmpty()) {
Locale locale = Locale.getDefault(Locale.Category.FORMAT);
if (chrono == null) {
chrono = IsoChronology.INSTANCE;
}
String pattern = "M/d/yyyy GGGGG";
DateTimeFormatter df = new DateTimeFormatterBuilder().parseLenient()
.appendPattern(pattern)
.toFormatter()
.withChronology(chrono)
.withDecimalStyle(DecimalStyle.of(locale));
TemporalAccessor temporal = df.parse(text);
ChronoLocalDate cDate = chrono.date(temporal);
return LocalDate.from(cDate);
}
return null;
}When the method is invoked with the following strings:
System.out.printf("%s%n", StringConverter.fromString("10/29/0008 H",
JapaneseChronology.INSTANCE));
System.out.printf("%s%n", StringConverter.fromString("10/29/0085 1",
MinguoChronology.INSTANCE));
System.out.printf("%s%n", StringConverter.fromString("10/29/2539 B.E.",
ThaiBuddhistChronology.INSTANCE));
System.out.printf("%s%n", StringConverter.fromString("6/16/1417 1",
HijrahChronology.INSTANCE));The printed strings should all convert back to October 29th, 1996:
1996-10-29 1996-10-29 1996-10-29 1996-10-29