极客教程Java Instant getLong()方法及示例
Instant类的 getLong(TemporalField field) 方法是用来从这个瞬间获取作为参数传递的指定字段的长值。这个方法查询这个瞬间的字段值，返回的值总是在该字段的有效范围内。当字段不被支持，方法无法返回int值时，就会产生一个异常。
语法
public int getLong(TemporalField field)
参数： 该方法接受一个参数 字段 ，它是要获取的字段。它不应该是空的。
返回： 该方法返回该字段的 长值 。
异常： 该方法会抛出以下异常。
- DateTimeException ：如果不能获得该字段的值，或者该值超出了该字段的有效值范围。
- UnsupportedTemporalTypeException ：如果该字段不被支持，或者数值范围超过了一个int。
- ArithmeticException : 如果发生数字溢出。
下面的程序说明了Instant.getLong()方法。
程序1 :
// Java program to demonstrate
// Instant.getLong(TemporalField field) method
import java.time.*;
import java.time.temporal.ChronoField;
public class GFG {
public static void main(String[] args)
{
// create a Instant object
Instant instant
= Instant.parse("2018-12-30T01:34:50.93Z");
// get all enum of chronofield
// and iterate through all enum values
for (ChronoField field : ChronoField.values()) {
try {
// get long value of field
long value = instant.getLong(field);
System.out.println("field : " + field
+ " || value : " + value);
}
catch (Exception e) {
System.out.println("field : " + field
+ " is not supported");
}
}
}
}
输出:
field : NanoOfSecond || value : 930000000
field : NanoOfDay is not supported
field : MicroOfSecond || value : 930000
field : MicroOfDay is not supported
field : MilliOfSecond || value : 930
field : MilliOfDay is not supported
field : SecondOfMinute is not supported
field : SecondOfDay is not supported
field : MinuteOfHour is not supported
field : MinuteOfDay is not supported
field : HourOfAmPm is not supported
field : ClockHourOfAmPm is not supported
field : HourOfDay is not supported
field : ClockHourOfDay is not supported
field : AmPmOfDay is not supported
field : DayOfWeek is not supported
field : AlignedDayOfWeekInMonth is not supported
field : AlignedDayOfWeekInYear is not supported
field : DayOfMonth is not supported
field : DayOfYear is not supported
field : EpochDay is not supported
field : AlignedWeekOfMonth is not supported
field : AlignedWeekOfYear is not supported
field : MonthOfYear is not supported
field : ProlepticMonth is not supported
field : YearOfEra is not supported
field : Year is not supported
field : Era is not supported
field : InstantSeconds || value : 1546133690
field : OffsetSeconds is not supported
程序2
// Java program to demonstrate
// Instant.getLong(TemporalField field) method
import java.time.*;
import java.time.temporal.ChronoField;
public class GFG {
public static void main(String[] args)
{
// create a Instant object
Instant instant
= Instant.parse("2018-12-30T01:34:50.93Z");
// get Instant second value from this Instant
// using getLong method
long secondvalue
= instant.getLong(
ChronoField.INSTANT_SECONDS);
// print result
System.out.println("Instant Seconds: "
+ secondvalue);
}
}
输出:
Instant Seconds: 1546133690
程序3： 获取UnsupportedTemporalTypeException
// Java program to demonstrate
// Instant.getLong(TemporalField field) method
import java.time.*;
import java.time.temporal.ChronoField;
public class GFG {
public static void main(String[] args)
{
// create a Instant object
Instant instant
= Instant.parse("2018-12-30T01:34:50.93Z");
// try to find AMPM_OF_DAY
// using ChronoField.AMPM_OF_DAY
// in getLong method
try {
long secondvalue
= instant.getLong(
ChronoField.AMPM_OF_DAY);
}
catch (Exception e) {
// print exception
System.out.println("Exception: " + e);
}
}
}
输出:
Exception:
java.time.temporal.UnsupportedTemporalTypeException:
Unsupported field: AmPmOfDay
参考资料: https://docs.oracle.com/javase/10/docs/api/java/time/Instant.html#get(java.time.temporal.TemporalField)