<dependency> <groupId>io.timely</groupId> <artifactId>timely-core</artifactId> <version>1.0.0</version> </dependency> long timestamp = 1631913600000L; // 2021-09-18 00:00:00 UTC Date date = Timely.Timestamp.toDate(timestamp); Date date = new Date(); long timestamp = Timely.Timestamp.fromDate(date); long timestamp = 1631913600000L; // 2021-09-18 00:00:00 UTC String strDate = Timely.Timestamp.toString(timestamp); long timestamp1 = 1631913600000L; // 2021-09-18 00:00:00 UTC long timestamp2 = 1632000000000L; // 2021-09-19 00:00:00 UTC long diffSeconds = Timely.Timestamp.diff(timestamp1, timestamp2);