Java Date Time - ZonedDateTime.query() Examples

package com.logicbig.example.zoneddatetime;

import java.time.*;
import java.time.chrono.Chronology;
import java.time.temporal.TemporalQueries;
import java.time.temporal.TemporalUnit;

public class QueryExample {

    public static void main(String... args) {
        ZonedDateTime d = ZonedDateTime.now();
        System.out.println(d);

        LocalTime t = d.query(TemporalQueries.localTime());
        System.out.println(t);

        ZoneOffset z = d.query(TemporalQueries.offset());
        System.out.println(z);

        TemporalUnit p = d.query(TemporalQueries.precision());
        System.out.println(p);

        ZoneId z2 = d.query(TemporalQueries.zone());
        System.out.println(z2);

        LocalDate d2 = d.query(TemporalQueries.localDate());
        System.out.println(d2);

        Chronology c = d.query(TemporalQueries.chronology());
        System.out.println(c);
    }
}

package com.logicbig.example.zoneddatetime;

import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.temporal.TemporalAccessor;
import java.time.temporal.TemporalQuery;

public class QueryExample2 {

    public static void main(String... args) {
        ZonedDateTime d = ZonedDateTime.now(ZoneId.of("Asia/Tokyo"));
        System.out.println(d);

        Boolean b = d.query(ValidTimeQuery);
        System.out.println("Is the given time zone in Asia? " + b);
    }

    public static final TemporalQuery<Boolean> ValidTimeQuery = new TemporalQuery<Boolean>() {
        @Override
        public Boolean queryFrom(TemporalAccessor temporal) {
            //check if the underlying time  zone is in Asia
            ZoneId id = ZoneId.from(temporal);
            String stringId = id.getId();
            return stringId.startsWith("Asia");
        }
    };
}