Java tutorial
//package com.java2s; /* Copyright 2012-2013, Polyvi Inc. (http://polyvi.github.io/openxface) This program is distributed under the terms of the GNU General Public License. This file is part of xFace. xFace 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. xFace 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 xFace. If not, see <http://www.gnu.org/licenses/>. */ import java.io.FileNotFoundException; import java.io.IOException; import java.io.RandomAccessFile; import java.nio.channels.FileChannel; public class Main { public static long truncateFile(String fileName, long size) throws FileNotFoundException, IOException { RandomAccessFile raf = new RandomAccessFile(fileName, "rw"); if (raf.length() >= size) { FileChannel channel = raf.getChannel(); channel.truncate(size); return size; } return raf.length(); } }