java 根据类名示例化类_Java即时类| from（）方法与示例

java 根据类名示例化类

即时类from()方法 (Instant Class from() method)

from() method is available in java.time package.
from()方法在java.time包中可用。
from() method is used to return a copy of the Instant from the given TemporalAccessor object.
from()方法用于从给定的TemporalAccessor对象返回Instant的副本。
from() method is a static method, it is accessible with the class name and if we try to access the method with the class object then we will not get an error.
from()方法是一个静态方法，可以使用类名进行访问，如果尝试使用类对象访问该方法，则不会收到错误。
from() method may throw an exception at the time of returning Instant from the given temp_acc.
从给定的temp_acc返回Instant时， from()方法可能会引发异常。

DateTimeException: This exception may throw when the given templ_acc couldn't convert into Instant.
DateTimeException ：当给定的templ_acc无法转换为Instant时，可能抛出此异常。

Syntax:

句法：

    public static Instant from(TemporalAccessor temp_acc);

Parameter(s):

参数：

TemporalAccessor temp_acc – represents the temporal accessor to convert to Instant.
TemporalAccessor temp_acc –表示要转换为Instant的临时访问器。

Return value:

返回值：

The return type of this method is Instant, it returns the Instant that the holds the same value from the given object.

此方法的返回类型为Instant ，它返回Instant，该Instant具有给定对象的相同值。

Example:

例：

// Java program to demonstrate the example 
// of Instant from(TemporalAccessor temp_acc)
// method of Instant
import java.time.*;
public class FromOfInstant {
public static void main(String args[]) {
// Instantiates a OffsetDateTime 
// and a ZonedDateTime object
OffsetDateTime off_da_time = OffsetDateTime.now();
ZonedDateTime zo_da_time = ZonedDateTime.parse("2008-07-06T20:25:30.213+03:00[Africa/Asmara]");
// Display off_da_time
// and zo_da_time
System.out.println("OffsetDateTime off_da_time: ");
System.out.println("off_da_time: " + off_da_time);
System.out.println();
System.out.println("ZonedDateTime zo_da_time: ");
System.out.println("zo_da_time: " + zo_da_time);
System.out.println();
// Here, this method creates an Instant
// from the given TemporalAccessor i.e.
// here we are creating an Instant(ins)
// from the given OffsetDateTime(off_da_time)
Instant inst = Instant.from(off_da_time);
// Display inst
System.out.println("Instant.from(off_da_time): " + inst);
// Here, this method creates an Instant
// from the given TemporalAccessor i.e.
// here we are creating an Instant(ins)
// from the given ZonedDateTime(zo_da_time)
inst = Instant.from(zo_da_time);
// Display inst
System.out.println("Instant.from(zo_da_time): " + inst);
}
}

Output

输出量

OffsetDateTime off_da_time: 
off_da_time: 2020-05-21T22:00:46.891244ZZonedDateTime zo_da_time: 
zo_da_time: 2008-07-06T20:25:30.213+03:00[Africa/Asmara]Instant.from(off_da_time): 2020-05-21T22:00:46.891244Z
Instant.from(zo_da_time): 2008-07-06T17:25:30.213Z