Timestamp in ObjectId of MongoDB

MongoUtil.java

public abstract class EdpMongoUtil {

    /**
     * @param objectId ObjectId of MongoDB
     * @return time of java.time.Instant
     */
    public static Instant timeFromObjectId(String objectId) {
        return Instant.ofEpochMilli(Integer.parseInt(objectId.substring(0, 8), 16) * 1000);
    }

    /**
     * @param time time of java.time.Instant
     * @return ObjectId of MongoDB
     */
    public static String objectIdFromTime(Instant time) {
        return Integer.toString((int) (time.toEpochMilli() / 1000L), 16) + "0000000000000000";
    }
    
}