The method java.time.Clock.offset(Clock,Duration) returns a wrapper around given Clock with the specified Duration added. This clock implementation allows easily to jump into the past and future.

The signature of the java.time.Clock.offset(Clock,Duration) method is as follows:

public static Clock offset(
        Clock baseClock,
        Duration offsetDuration)

The method is available since Java 8.

• Clock baseClock: the clock to which add the duration to, not null,
• Duration offset: the duration to add, not null.

Returns a clock based on the given clock with the duration added, never null.

• NullPointerException: when any of the parameters is null.

In the following code we use java.time.Clock.offset(Clock baseClock, Duration offset):

package com.farenda.java.time;

import java.time.Clock;
import java.time.Duration;
import java.time.ZoneId;

import static java.time.Instant.ofEpochMilli;

public class ClockExample {

    public static void main(String[] args) {
        Clock constClock = Clock.fixed(
                ofEpochMilli(0), ZoneId.systemDefault());
        System.out.println("Current millis: "
                + constClock.millis());

        // go to the future:
        Clock clock = Clock.offset(
                constClock, Duration.ofSeconds(10));
        System.out.println("Current millis: "
                + clock.millis());

        // revind back with negative value:
        clock = Clock.offset(clock, Duration.ofSeconds(-5));
        System.out.println("Current millis: "
                + clock.millis());

        // The duration 0 returns the same clock:
        clock = Clock.offset(constClock, Duration.ZERO);
        System.out.println("Current millis: "
                + clock.millis());
        System.out.println("Identical? "
                + (constClock == clock));
    }
}

The above code produces the following output:

Current millis: 0
Current millis: 10000
Current millis: 5000
Current millis: 0
Identical? true

• More about Fixed Clock