Here you can find the source of getStartOfDay(ZoneId zoneId, ZonedDateTime time)
public static ZonedDateTime getStartOfDay(ZoneId zoneId, ZonedDateTime time)
//package com.java2s; /******************************************************************************* * Copyright (c) 2017 Stichting Yona Foundation This Source Code Form is subject to the terms of the Mozilla Public License, v. * 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/. *******************************************************************************/ import java.time.ZoneId; import java.time.ZonedDateTime; import java.time.temporal.ChronoUnit; public class Main { public static ZonedDateTime getStartOfDay(ZoneId zoneId, ZonedDateTime time) { return time.withZoneSameInstant(zoneId).truncatedTo(ChronoUnit.DAYS); }//w ww . ja v a 2s .c o m }