The method java.time.Clock.fixed() returns a clock that always returns the same time. This type of clock is mainly useful in testing.

The signature of the java.time.Clock.fixed() method is as follows:

public static Clock fixed(Instant fixedInstant, ZoneId zone)

The method is available since Java 8.

• Instant fixedInstant: the instant to use, not null
• ZoneId zone: the time-zone that will be used to convert the instant to date-time, not null

Returns a clock that always returns the same time.

The method throws no exceptions.

In the following code we use java.time.Clock.fixed():

package com.farenda.java.time;

import java.time.Clock;
import java.time.ZoneId;
import java.util.concurrent.TimeUnit;

import static java.time.Instant.ofEpochMilli;

public class ClockExample {

    public static void main(String[] args) {
        Clock clock = Clock.fixed(
                ofEpochMilli(0),
                ZoneId.systemDefault());
        System.out.println("Current millis: " + clock.millis());
        try {
            // wait for a while:
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Current millis: " + clock.millis());
    }
}

The above code produces the following output:

Current millis: 0
Current millis: 0