Here you can find the source of roundValue(Double value)
protected static double roundValue(Double value)
//package com.java2s; /*// w w w . ja v a 2 s .c om * Boltzmann 3D, a kinetic theory demonstrator * Copyright (C) 2013 Dr. Randall B. Shirts * * 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/>. */ public class Main { /** Rounds to 2 significant figures. */ protected static double roundValue(Double value) { if (value.isInfinite() || value.isNaN() || value == 0) return value; double val = value; int shift = 0; if (Math.abs(val) >= 1) // |val| >= 1 { //Make sure we're starting with a value >= 10 (2 digits). val *= 10; //Consider the two leading numbers. while (Math.abs(val) > 100) { val /= 10.0; shift++; } //Set all lesser numbers to zero. val = Math.round(val); //Restore original magnitude. for (; shift > 0; shift--) val *= 10; //One last divide to offset the first multiplication. val /= 10; } else // 0 < |val| < 1 { //Consider the two leading numbers. while (Math.abs(val) < 10) { val *= 10; shift++; } //Set all lesser numbers to zero. val = Math.round(val); //Restore original magnitude. for (; shift > 0; shift--) val /= 10.0; } return val; } }