Java ChronoLocalDateTime getLong()方法及示例

Java中 ChronoLocalDateTime 接口的 getLong() 方法用于从ChronoLocalDateTime中获取作为输入的指定字段的长值。该方法向ChronoLocalDateTime查询该字段的值，返回值总是在该字段的有效范围内。当该字段不被支持且该方法无法返回int值时，就会抛出一个异常。

语法

long getLong(TemporalField field)

参数： 该方法接受一个单一的参数 字段 ，代表要获取的字段。这是一个强制性参数，它不应该是空的。

返回值： 该方法返回该字段的一个 int 值。

异常： 该方法会抛出以下异常。

以下程序说明了getLong()方法：

程序1 :

// Java program to demonstrate// ChronoLocalDateTime.getLong() method  import java.time.*;import java.time.chrono.*;import java.time.temporal.ChronoField;  public class GFG {    public static void main(String[] args)    {          // create a ChronoLocalDateTime object        ChronoLocalDateTime localDT            = LocalDateTime                  .parse("2019-12-31T19:15:30");          // get all enum of chronofield        // and iterate through all enum values        for (ChronoField field : ChronoField.values()) {              try {                // get long value of field                long value = localDT.getLong(field);                System.out.println(field                                   + " : "                                   + value);            }            catch (Exception e) {                System.out.println("e " + field);            }        }    }}

输出:

NanoOfSecond : 0NanoOfDay : 69330000000000MicroOfSecond : 0MicroOfDay : 69330000000MilliOfSecond : 0MilliOfDay : 69330000SecondOfMinute : 30SecondOfDay : 69330MinuteOfHour : 15MinuteOfDay : 1155HourOfAmPm : 7ClockHourOfAmPm : 7HourOfDay : 19ClockHourOfDay : 19AmPmOfDay : 1DayOfWeek : 2AlignedDayOfWeekInMonth : 3AlignedDayOfWeekInYear : 1DayOfMonth : 31DayOfYear : 365EpochDay : 18261AlignedWeekOfMonth : 5AlignedWeekOfYear : 53MonthOfYear : 12ProlepticMonth : 24239YearOfEra : 2019Year : 2019Era : 1e InstantSecondse OffsetSeconds

程序2

// Java program to demonstrate// ChronoLocalDateTime.getLong() method  import java.time.*;import java.time.chrono.*;import java.time.temporal.ChronoField;  public class GFG {    public static void main(String[] args)    {          // create a ChronoLocalDateTime object        ChronoLocalDateTime localDT            = LocalDateTime                  .parse("2018-10-25T23:12:31.123");          // try to find AMPM_OF_DAY        // using ChronoField.AMPM_OF_DAY        // in getLong method        try {              long value                = localDT.getLong(                    ChronoField.AMPM_OF_DAY);              // print result            System.out.println("AMPM_OF_DAY value: "                               + value);        }        catch (Exception e) {              // print exception            System.out.println("Exception: " + e);        }    }}

输出:

AMPM_OF_DAY value: 1

参考资料: https://docs.oracle.com/javase/9/docs/api/java/time/temporal/TemporalAccessor.html#getLong-java.time.temporal.TemporalField-