Here you can find the source of sleep(long millis)
static void sleep(long millis)
//package com.java2s; /*// www. j a v a2 s .c om * Copyright (C) 2011-2017 Cojen.org * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ public class Main { static void sleep(long millis) { if (millis <= 0) { if (millis < 0) { throw new IllegalArgumentException("" + millis); } return; } long end = System.currentTimeMillis() + millis; do { try { Thread.sleep(millis); } catch (InterruptedException e) { } } while ((millis = end - System.currentTimeMillis()) > 0); } }