The from() method of the ZoneId class used to get instance of ZoneId from TemporalAccessor object passed as parameter.This method obtains a zone based on the TemporalAccessor which represents an arbitrary set of date and time information, which this method converts to an instance of ZoneId.
Syntax:
public static ZoneId from(TemporalAccessor temporal)
Parameters: This method accepts a single parameter temporal which represents the temporal object to convert, It can’t be null.
Return value: This method returns the zone ID, which can not be null.
Exception: This method throws the DateTimeException if this method is unable to convert temporal to a ZoneId.
Below programs illustrate the from() method:
Program 1:
// Java program to demonstrate// ZoneId.from() method  import java.time.*;  public class GFG {    public static void main(String[] args)    {          // create TemporalAccessor object        ZonedDateTime zoneddatetime            = ZonedDateTime.parse("2018-10-25T23:12:31.123+02:00[Europe/Paris]");          // get ZoneId from this TemporalAccessor        ZoneId response = ZoneId.from(zoneddatetime);          // print result        System.out.println("Zone Id got from "                           + "TemporalAccessor object \n"                           + zoneddatetime + "\nis " + response);    }} |
Zone Id got from TemporalAccessor object 2018-10-25T23:12:31.123+02:00[Europe/Paris] is Europe/Paris
Program 2:
// Java program to demonstrate// ZoneId.from() method  import java.time.*;  public class GFG {    public static void main(String[] args)    {          // create TemporalAccessor object        ZonedDateTime zoneddatetime            = ZonedDateTime.now();          // get ZoneId from this TemporalAccessor        ZoneId response = ZoneId.from(zoneddatetime);          // print result        System.out.println("Zone Id got from "                           + "TemporalAccessor object \n"                           + zoneddatetime + "\nis " + response);    }} |
Zone Id got from TemporalAccessor object 2018-12-10T18:20:03.637Z[Etc/UTC] is Etc/UTC
References:
https://docs.oracle.com/javase/10/docs/api/java/time/ZoneId.html#from(java.lang.Object)
