File file = new File(args[0]);
if (file.exists()) {
SecureRandom random = new SecureRandom();
RandomAccessFile raf = new RandomAccessFile(file, "rw");
FileChannel channel = raf.getChannel();
MappedByteBuffer buffer
= channel.map(FileChannel.MapMode.READ_WRITE, 0, raf.length());
// overwrite with zeros
while (buffer.hasRemaining()) {
buffer.put((byte) 0);
}
buffer.force();
buffer.rewind();
// overwrite with ones
while (buffer.hasRemaining()) {
buffer.put((byte) 0xFF);
}
buffer.force();
buffer.rewind();
// overwrite with random data; one byte at a time
byte[] data = new byte[1];
while (buffer.hasRemaining()) {
random.nextBytes(data);
buffer.put(data[0]);
}
buffer.force();
file.delete();
}
