Java Utililty Methods File Copy nio

if (f1 == null || f2 == null || !f1.exists()) {
    return;
int length = 2097152;
FileInputStream in = new FileInputStream(f1);
FileOutputStream out = new FileOutputStream(f2);
FileChannel inC = in.getChannel();
FileChannel outC = out.getChannel();
...

if (visibleFilesOnly && isHiddenOrDotFile(source)) {
    return;
if (dest.exists()) {
    System.err.println("Destination File Already Exists: " + dest);
FileChannel in = null, out = null;
try {
...

FileInputStream input = null;
FileChannel inputChannel = null;
FileOutputStream output = null;
FileChannel outputChannel = null;
try {
    input = new FileInputStream(src);
    inputChannel = input.getChannel();
    output = new FileOutputStream(dest);
...

long r = 0;
FileOutputStream fos = new FileOutputStream(dstFile);
try {
    ByteBuffer bb = ByteBuffer.allocate(32768);
    for (int n; (n = srcFc.read(bb)) != -1;) {
        bb.flip();
        fos.write(bb.array(), 0, bb.limit());
        bb.clear();
...

if (source == null || dest == null) {
    throw new IllegalArgumentException("Ni origen ni destino de la copia pueden ser nulos"); 
final FileInputStream is = new FileInputStream(source);
final FileOutputStream os = new FileOutputStream(dest);
final FileChannel in = is.getChannel();
final FileChannel out = os.getChannel();
final MappedByteBuffer buf = in.map(FileChannel.MapMode.READ_ONLY, 0, in.size());
...

FileChannel in = new FileInputStream(source).getChannel(), out = new FileOutputStream(target).getChannel();
ByteBuffer buffer = ByteBuffer.allocate(1024);
while (in.read(buffer) != -1) {
    buffer.flip(); 
    out.write(buffer);
    buffer.clear(); 
out.close();
...

FileChannel in = null;
FileChannel out = null;
try {
    in = new FileInputStream(source).getChannel();
    out = new FileOutputStream(target).getChannel();
    ByteBuffer buffer = ByteBuffer.allocateDirect(BUFFER);
    int readSize = in.read(buffer);
    long totalRead = 0;
...

RandomAccessFile readFile = new RandomAccessFile(sourcePath, "r");
RandomAccessFile writeFile = new RandomAccessFile(targetPath, "rw");
long fileLength = readFile.length();
MappedByteBuffer in = readFile.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, fileLength);
MappedByteBuffer out = writeFile.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, fileLength);
for (int i = 0; i < fileLength; i++) {
    out.put(in.get());
readFile.close();
writeFile.close();
in.clear();
out.clear();

final FileOutputStream fos = new FileOutputStream(file);
ReadableByteChannel source = null;
FileChannel target = null;
try {
    source = Channels.newChannel(is);
    target = fos.getChannel();
    final ByteBuffer buffer = ByteBuffer.allocateDirect(16 * 1024);
    while (source.read(buffer) != -1) {
...

return copyToFile(is, File.createTempFile(prefix, suffix));