Here you can find the source of writeBigInteger(BigInteger integer, DataOutputStream out)
public static void writeBigInteger(BigInteger integer, DataOutputStream out) throws IOException
//package com.java2s; /*/*from w w w. j a va 2 s . c om*/ * This file is part of dhcp4java, a DHCP API for the Java language. * (c) 2006 Stephan Hadinger * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ import java.io.DataOutputStream; import java.io.IOException; import java.math.BigInteger; public class Main { /** * Write a (reasonably short) BigInteger to a stream. * <at> param integer the BigInteger to write * <at> param out the stream to write it to */ public static void writeBigInteger(BigInteger integer, DataOutputStream out) throws IOException { if (integer.signum() == -1) { //dump("Negative BigInteger", Logger.ERROR, true); throw new IllegalStateException("Negative BigInteger!"); } byte[] buf = integer.toByteArray(); if (buf.length > Short.MAX_VALUE) { throw new IllegalStateException("Too long: " + buf.length); } out.writeShort((short) buf.length); out.write(buf); } }