Here you can find the source of toArray(List
private static final double[] toArray(List<Double> list)
//package com.java2s; /*// w w w . j a v a2 s. co m * #%L * LA-iMageS Core * %% * Copyright (C) 2016 Marco Aur?lio Zezzi Arruda, Gustavo de Souza * Pess?a, Jos? Luis Capelo Mart?nez, Florentino Fdez-Riverola, Miguel * Reboiro-Jato, Hugo L?pez-Fdez, and Daniel Glez-Pe?a * %% * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU 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 General Public License for more details. * * You should have received a copy of the GNU General Public * License along with this program. If not, see * <http://www.gnu.org/licenses/gpl-3.0.html>. * #L% */ import java.util.List; public class Main { private static final double[] toArray(List<Double> list) { return list.stream().mapToDouble(Double::valueOf).toArray(); } }