Here you can find the source of copyFile(File srcFile, File dstFile)
static void copyFile(File srcFile, File dstFile) throws IOException
//package com.java2s; /*//from w w w . j a v a 2 s.c om Copyright (c) 2015 James Ahlborn Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; public class Main { static void copyFile(File srcFile, File dstFile) throws IOException { // FIXME should really be using commons io FileUtils here, but don't want // to add dep for one simple test method byte[] buf = new byte[1024]; OutputStream ostream = new FileOutputStream(dstFile); InputStream istream = new FileInputStream(srcFile); try { int numBytes = 0; while ((numBytes = istream.read(buf)) >= 0) { ostream.write(buf, 0, numBytes); } } finally { ostream.close(); } } }