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Create and edit a File object in java without physically writing to hard disc

I am trying to create and edit a text file object in java. But once I execute the code, it is physically writing the file in root folder from which the program being executed. How can I do the same without physically writing the text file to hard disc?
File file = new File("tempFile.txt"); // Now the file is not created physically
writeIntoFile(file, listOfString); // After this, the file is created in disc
private static void writeIntoFile(File file, List<String> contents) {
Writer output;
try {
output = new BufferedWriter(new FileWriter(file.getPath(), true));
for (String content : contents) {
output.append(content);
output.append("\r\n");
}
output.close();
} catch (Exception e) {
e.printStackTrace();
}
}

Thanks #Gerome Tahud. The below code did the trick!
private static byte[] writeIntoFile(List<String> contents) {
try {
if (null != contents && contents.size() > 0) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
for (String content : contents) {
content = content + "\r\n";
InputStream inputStream = new ByteArrayInputStream(content.getBytes());
byte[] buffer = new byte[8192];
int bytesRead;
while ((bytesRead = inputStream.read(buffer)) != -1) {
baos.write(buffer, 0, bytesRead);
}
}
return baos.toByteArray();
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}

Runtime error :java.rmi.NoSuchObjectException: no such object in table

i'm attempting to fetch a list of files from server and copy them to directory .
and this error prompts.
java.rmi.NoSuchObjectException: no such object in table
at javafxhomeui_1.HomeUI_2Controller.writeFileToLocalHDD(HomeUI_2Controller.java:427)
at javafxhomeui_1.HomeUI_2Controller.initialize(HomeUI_2Controller.java:312)
HomeUI_2Controller.java
RemoteInputStream ris= null;
File[] iconlist=null;
try {
File appicon=new File("D:\\SERVER\\Server Content\\Apps\\icons");
iconlist=appicon.listFiles();
for (File file1 : iconlist) {
ris = downloadcontroller.getFile(file1.getAbsolutePath());
System.out.println(file1.getName());
}
} catch (Exception ex) {
Logger.getLogger(HomeUI_2Controller.class.getName()).log(Level.SEVERE, null, ex);
}
try {
for (File file1 : iconlist) {
//System.out.println("D:\\client\\Temp\\"+file1.getName());
/*line:312 */ writeFileToLocalHDD(ris,"D:\\client\\Temp\\"+file1.getName());
}
} catch (Exception ex) {
Logger.getLogger(HomeUI_2Controller.class.getName()).log(Level.SEVERE, null, ex);
}
public static void writeFileToLocalHDD(RemoteInputStream inFile, String fileLocation) throws IOException {
// wrap RemoteInputStream as InputStream (all compression issues are dealt
// with in the wrapper code)
/* line:427*/ InputStream istream = RemoteInputStreamClient.wrap(inFile);
BufferedInputStream bis = new BufferedInputStream(istream);
//downloaded file...
File file = new File(fileLocation);
if (!file.exists()) {
file.createNewFile();
}
FileOutputStream fileOutputStream = new FileOutputStream(file);
FileChannel channel = fileOutputStream.getChannel();
byte b[] = new byte[1024];
long startTime = System.currentTimeMillis();
while (bis.available()>0) {
bis.read(b);
System.out.println((System.currentTimeMillis() - startTime)/1000);
ByteBuffer buffer = ByteBuffer.wrap(b);
channel.write(buffer);
}
bis.close();
fileOutputStream.flush();
channel.close();
fileOutputStream.close();
}
////////////////////////////////////////////////
public RemoteInputStream getFile(String fileName) throws IOException {
// create a RemoteStreamServer (note the finally block which only releases
// the RMI resources if the method fails before returning.)
//read data
RemoteInputStreamServer istream = null;
try {
File file = new File(fileName);
System.out.println(file.exists());
FileInputStream fileInputStream = new FileInputStream(file);
BufferedInputStream bufferedInputStream = new BufferedInputStream(
fileInputStream);
istream = new SimpleRemoteInputStream(bufferedInputStream);
// export the final stream for returning to the client
//send data
RemoteInputStream result = istream.export();
// after all the hard work, discard the local reference (we are passing
// responsibility to the client)
istream = null;
return result;
} finally {
// we will only close the stream here if the server fails before
// returning an exported stream
if (istream != null) {
istream.close();
}
}
}
////////////////////////////////////

rmi works on a stub and skeleton structure.
Exception that is thrown has something to do with rmi Registry. The Object is not found because it is not available from RMI resistry.
A NoSuchObjectException is thrown if an attempt is made to invoke a method on an object that no longer exists in the remote virtual machine
as in javaDoc of the Exception thrown

How to make a copy of a file in android?

In my app I want to save a copy of a certain file with a different name (which I get from user)
Do I really need to open the contents of the file and write it to another file?
What is the best way to do so?

To copy a file and save it to your destination path you can use the method below.
public static void copy(File src, File dst) throws IOException {
InputStream in = new FileInputStream(src);
try {
OutputStream out = new FileOutputStream(dst);
try {
// Transfer bytes from in to out
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
} finally {
out.close();
}
} finally {
in.close();
}
}
On API 19+ you can use Java Automatic Resource Management:
public static void copy(File src, File dst) throws IOException {
try (InputStream in = new FileInputStream(src)) {
try (OutputStream out = new FileOutputStream(dst)) {
// Transfer bytes from in to out
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
}
}
}

Alternatively, you can use FileChannel to copy a file. It might be faster than the byte copy method when copying a large file. You can't use it if your file is bigger than 2GB though.
public void copy(File src, File dst) throws IOException {
FileInputStream inStream = new FileInputStream(src);
FileOutputStream outStream = new FileOutputStream(dst);
FileChannel inChannel = inStream.getChannel();
FileChannel outChannel = outStream.getChannel();
inChannel.transferTo(0, inChannel.size(), outChannel);
inStream.close();
outStream.close();
}

Kotlin extension for it
fun File.copyTo(file: File) {
inputStream().use { input ->
file.outputStream().use { output ->
input.copyTo(output)
}
}
}

This is simple on Android O (API 26), As you see:
#RequiresApi(api = Build.VERSION_CODES.O)
public static void copy(File origin, File dest) throws IOException {
Files.copy(origin.toPath(), dest.toPath());
}

These worked nice for me
public static void copyFileOrDirectory(String srcDir, String dstDir) {
try {
File src = new File(srcDir);
File dst = new File(dstDir, src.getName());
if (src.isDirectory()) {
String files[] = src.list();
int filesLength = files.length;
for (int i = 0; i < filesLength; i++) {
String src1 = (new File(src, files[i]).getPath());
String dst1 = dst.getPath();
copyFileOrDirectory(src1, dst1);
}
} else {
copyFile(src, dst);
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static void copyFile(File sourceFile, File destFile) throws IOException {
if (!destFile.getParentFile().exists())
destFile.getParentFile().mkdirs();
if (!destFile.exists()) {
destFile.createNewFile();
}
FileChannel source = null;
FileChannel destination = null;
try {
source = new FileInputStream(sourceFile).getChannel();
destination = new FileOutputStream(destFile).getChannel();
destination.transferFrom(source, 0, source.size());
} finally {
if (source != null) {
source.close();
}
if (destination != null) {
destination.close();
}
}
}

Much simpler now with Kotlin:
File("originalFileDir", "originalFile.name")
.copyTo(File("newFileDir", "newFile.name"), true)
trueorfalse is for overwriting the destination file
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.io/java.io.-file/copy-to.html

It might be too late for an answer but the most convenient way is using
FileUtils's
static void copyFile(File srcFile, File destFile)
e.g. this is what I did
`
private String copy(String original, int copyNumber){
String copy_path = path + "_copy" + copyNumber;
try {
FileUtils.copyFile(new File(path), new File(copy_path));
return copy_path;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
`

in kotlin , just :
val fileSrc : File = File("srcPath")
val fileDest : File = File("destPath")
fileSrc.copyTo(fileDest)

Here is a solution that actually closes the input/output streams if an error occurs while copying. This solution utilizes apache Commons IO IOUtils methods for both copying and handling the closing of streams.
public void copyFile(File src, File dst) {
InputStream in = null;
OutputStream out = null;
try {
in = new FileInputStream(src);
out = new FileOutputStream(dst);
IOUtils.copy(in, out);
} catch (IOException ioe) {
Log.e(LOGTAG, "IOException occurred.", ioe);
} finally {
IOUtils.closeQuietly(out);
IOUtils.closeQuietly(in);
}
}

in Kotlin: a short way
// fromPath : Path the file you want to copy
// toPath : The path where you want to save the file
// fileName : name of the file that you want to copy
// newFileName: New name for the copied file (you can put the fileName too instead of put a new name)
val toPathF = File(toPath)
if (!toPathF.exists()) {
path.mkdir()
}
File(fromPath, fileName).copyTo(File(toPath, fileName), replace)
this is work for any file like images and videos

now in kotlin you could just use
file1.copyTo(file2)
where file1 is an object of the original file and file2 is an object of the new file you want to copy to

Simple and easy way...!
import android.os.FileUtils;
try (InputStream in = new FileInputStream(sourceFile);
OutputStream out = new FileOutputStream(destinationFile) ){
FileUtils.copy(in, out);
}catch(Exception e){
Log.d("ReactNative","Error copying file: "+e.getMessage());
}

What is the "Jodatime" / "Apache commons" of Zip/Unzip Java utilities?

I'm sure that there is a mature, widely used ZIP file utility out there, I just can't seem to find out. Something with the same maturity as Apache Commons, Google Collections, Joda Time
I'm trying to do the simplest task of getting a zip file as a byte array (ZipInputStream) and extract it to a folder. this seems like a very tedious task.
I would hope for a syntactic sugar API that does somethnig like this:
public class MyDreamZIPUtils
public static void extractToFolder(ZipInputStream zin, File outputFolderRoot){
...
}
public static void extractToFolder(ZipFile zf, File outputFolderRoot){
...
}
public static zipFolder(File folderToZip, File zippedFileLocation){
...
}
public static zipFolder(File folderToZip, ByteArrayOutputStream zipResult){
...
}
Anything like this?
Am I missing something?

http://commons.apache.org/compress/
I am sure you can write the "syntactic sugar" on top of that.
Javadoc: http://commons.apache.org/compress/apidocs/index.html

I used only Java API calls... I did not do all your methods. you can figure them out from here... Please note i do not claim that the code is bug free... use at your own risk :)
public static void extractToFolder(ZipInputStream zin, File outputFolderRoot)
throws IOException {
FileOutputStream fos = null;
byte[] buf = new byte[1024];
ZipEntry zipentry;
for (zipentry = zin.getNextEntry(); zipentry != null; zipentry = zin.getNextEntry()) {
try {
String entryName = zipentry.getName();
System.out.println("Extracting: " + entryName);
int n;
File newFile = new File(outputFolderRoot, entryName);
if (zipentry.isDirectory()) {
newFile.mkdirs();
continue;
} else {
newFile.getParentFile().mkdirs();
newFile.createNewFile();
}
fos = new FileOutputStream(newFile);
while ((n = zin.read(buf, 0, 1024)) > -1)
fos.write(buf, 0, n);
fos.close();
zin.closeEntry();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (fos != null)
try {
fos.close();
} catch (Exception ignore) {
}
}
}
zin.close();
}
public static void zipFolder(File folderToZip, File zippedFileLocation) throws IOException {
// create a ZipOutputStream to zip the data to
ZipOutputStream zos = new ZipOutputStream(new FileOutputStream(zippedFileLocation));
String path = "";
zipDir(folderToZip, zos, path);
// close the stream
zos.close();
}
private static void zipDir(File directory, ZipOutputStream zos, String path) throws IOException {
File zipDir = directory;
// get a listing of the directory content
String[] dirList = zipDir.list();
byte[] readBuffer = new byte[2156];
int bytesIn = 0;
// loop through dirList, and zip the files
for (int i = 0; i < dirList.length; i++) {
File f = new File(zipDir, dirList[i]);
if (f.isDirectory()) {
zipDir(new File(f.getPath()), zos, path + f.getName() + "/");
continue;
}
FileInputStream fis = new FileInputStream(f);
try {
ZipEntry anEntry = new ZipEntry(path + f.getName());
zos.putNextEntry(anEntry);
bytesIn = fis.read(readBuffer);
while (bytesIn != -1) {
zos.write(readBuffer, 0, bytesIn);
bytesIn = fis.read(readBuffer);
}
} finally {
fis.close();
}
}
}
Reference Java2s

Copying files from one directory to another in Java

I want to copy files from one directory to another (subdirectory) using Java. I have a directory, dir, with text files. I iterate over the first 20 files in dir, and want to copy them to another directory in the dir directory, which I have created right before the iteration.
In the code, I want to copy the review (which represents the ith text file or review) to trainingDir. How can I do this? There seems not to be such a function (or I couldn't find). Thank you.
boolean success = false;
File[] reviews = dir.listFiles();
String trainingDir = dir.getAbsolutePath() + "/trainingData";
File trDir = new File(trainingDir);
success = trDir.mkdir();
for(int i = 1; i <= 20; i++) {
File review = reviews[i];
}

For now this should solve your problem
File source = new File("H:\\work-temp\\file");
File dest = new File("H:\\work-temp\\file2");
try {
FileUtils.copyDirectory(source, dest);
} catch (IOException e) {
e.printStackTrace();
}
FileUtils class from apache commons-io library, available since version 1.2.
Using third party tools instead of writing all utilities by ourself seems to be a better idea. It can save time and other valuable resources.

There is no file copy method in the Standard API (yet). Your options are:
Write it yourself, using a FileInputStream, a FileOutputStream and a buffer to copy bytes from one to the other - or better yet, use FileChannel.transferTo()
User Apache Commons' FileUtils
Wait for NIO2 in Java 7

In Java 7, there is a standard method to copy files in java:
Files.copy.
It integrates with O/S native I/O for high performance.
See my A on Standard concise way to copy a file in Java? for a full description of usage.

The example below from Java Tips is rather straight forward. I have since switched to Groovy for operations dealing with the file system - much easier and elegant. But here is the Java Tips one I used in the past. It lacks the robust exception handling that is required to make it fool-proof.
public void copyDirectory(File sourceLocation , File targetLocation)
throws IOException {
if (sourceLocation.isDirectory()) {
if (!targetLocation.exists()) {
targetLocation.mkdir();
}
String[] children = sourceLocation.list();
for (int i=0; i<children.length; i++) {
copyDirectory(new File(sourceLocation, children[i]),
new File(targetLocation, children[i]));
}
} else {
InputStream in = new FileInputStream(sourceLocation);
OutputStream out = new FileOutputStream(targetLocation);
// Copy the bits from instream to outstream
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
out.close();
}
}

If you want to copy a file and not move it you can code like this.
private static void copyFile(File sourceFile, File destFile)
throws IOException {
if (!sourceFile.exists()) {
return;
}
if (!destFile.exists()) {
destFile.createNewFile();
}
FileChannel source = null;
FileChannel destination = null;
source = new FileInputStream(sourceFile).getChannel();
destination = new FileOutputStream(destFile).getChannel();
if (destination != null && source != null) {
destination.transferFrom(source, 0, source.size());
}
if (source != null) {
source.close();
}
if (destination != null) {
destination.close();
}
}

apache commons Fileutils is handy.
you can do below activities.
copying file from one directory to another directory.
use copyFileToDirectory(File srcFile, File destDir)
copying directory from one directory to another directory.
use copyDirectory(File srcDir, File destDir)
copying contents of one file to another
use static void copyFile(File srcFile, File destFile)

Spring Framework has many similar util classes like Apache Commons Lang. So there is org.springframework.util.FileSystemUtils
File src = new File("/home/user/src");
File dest = new File("/home/user/dest");
FileSystemUtils.copyRecursively(src, dest);

You seem to be looking for the simple solution (a good thing). I recommend using Apache Common's FileUtils.copyDirectory:
Copies a whole directory to a new
location preserving the file dates.
This method copies the specified
directory and all its child
directories and files to the specified
destination. The destination is the
new location and name of the
directory.
The destination directory is created
if it does not exist. If the
destination directory did exist, then
this method merges the source with the
destination, with the source taking
precedence.
Your code could like nice and simple like this:
File trgDir = new File("/tmp/myTarget/");
File srcDir = new File("/tmp/mySource/");
FileUtils.copyDirectory(srcDir, trgDir);

File sourceFile = new File("C:\\Users\\Demo\\Downloads\\employee\\"+img);
File destinationFile = new File("\\images\\" + sourceFile.getName());
FileInputStream fileInputStream = new FileInputStream(sourceFile);
FileOutputStream fileOutputStream = new FileOutputStream(
destinationFile);
int bufferSize;
byte[] bufffer = new byte[512];
while ((bufferSize = fileInputStream.read(bufffer)) > 0) {
fileOutputStream.write(bufffer, 0, bufferSize);
}
fileInputStream.close();
fileOutputStream.close();

Java 8
Path sourcepath = Paths.get("C:\\data\\temp\\mydir");
Path destinationepath = Paths.get("C:\\data\\temp\\destinationDir");
Files.walk(sourcepath)
.forEach(source -> copy(source, destinationepath.resolve(sourcepath.relativize(source))));
Copy Method
static void copy(Path source, Path dest) {
try {
Files.copy(source, dest, StandardCopyOption.REPLACE_EXISTING);
} catch (Exception e) {
throw new RuntimeException(e.getMessage(), e);
}
}

import static java.nio.file.StandardCopyOption.*;
...
Files.copy(source, target, REPLACE_EXISTING);
Source: https://docs.oracle.com/javase/tutorial/essential/io/copy.html

Apache commons FileUtils will be handy, if you want only to move files from the source to target directory rather than copy the whole directory, you can do:
for (File srcFile: srcDir.listFiles()) {
if (srcFile.isDirectory()) {
FileUtils.copyDirectoryToDirectory(srcFile, dstDir);
} else {
FileUtils.copyFileToDirectory(srcFile, dstDir);
}
}
If you want to skip directories, you can do:
for (File srcFile: srcDir.listFiles()) {
if (!srcFile.isDirectory()) {
FileUtils.copyFileToDirectory(srcFile, dstDir);
}
}

Inspired by Mohit's answer in this thread. Applicable only for Java 8.
The following can be used to copy everything recursively from one folder to another:
public static void main(String[] args) throws IOException {
Path source = Paths.get("/path/to/source/dir");
Path destination = Paths.get("/path/to/dest/dir");
List<Path> sources = Files.walk(source).collect(toList());
List<Path> destinations = sources.stream()
.map(source::relativize)
.map(destination::resolve)
.collect(toList());
for (int i = 0; i < sources.size(); i++) {
Files.copy(sources.get(i), destinations.get(i));
}
}
Stream-style FTW.
Upd 2019-06-10: important note - close the stream (e.g. using try-with-resource) acquired by Files.walk call. Thanks to #jannis for the point.

Below is Brian's modified code which copies files from source location to destination location.
public class CopyFiles {
public static void copyFiles(File sourceLocation , File targetLocation)
throws IOException {
if (sourceLocation.isDirectory()) {
if (!targetLocation.exists()) {
targetLocation.mkdir();
}
File[] files = sourceLocation.listFiles();
for(File file:files){
InputStream in = new FileInputStream(file);
OutputStream out = new FileOutputStream(targetLocation+"/"+file.getName());
// Copy the bits from input stream to output stream
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
out.close();
}
}
}

You can workaround with copy the source file to a new file and delete the original.
public class MoveFileExample {
public static void main(String[] args) {
InputStream inStream = null;
OutputStream outStream = null;
try {
File afile = new File("C:\\folderA\\Afile.txt");
File bfile = new File("C:\\folderB\\Afile.txt");
inStream = new FileInputStream(afile);
outStream = new FileOutputStream(bfile);
byte[] buffer = new byte[1024];
int length;
//copy the file content in bytes
while ((length = inStream.read(buffer)) > 0) {
outStream.write(buffer, 0, length);
}
inStream.close();
outStream.close();
//delete the original file
afile.delete();
System.out.println("File is copied successful!");
} catch(IOException e) {
e.printStackTrace();
}
}
}

This prevents file from being corrupted!
Just download the following jar!
Jar File
Download Page
import org.springframework.util.FileCopyUtils;
private static void copyFile(File source, File dest) throws IOException {
//This is safe and don't corrupt files as FileOutputStream does
File src = source;
File destination = dest;
FileCopyUtils.copy(src, dest);
}

File dir = new File("D:\\mital\\filestore");
File[] files = dir.listFiles(new File_Filter("*"+ strLine + "*.txt"));
for (File file : files){
System.out.println(file.getName());
try {
String sourceFile=dir+"\\"+file.getName();
String destinationFile="D:\\mital\\storefile\\"+file.getName();
FileInputStream fileInputStream = new FileInputStream(sourceFile);
FileOutputStream fileOutputStream = new FileOutputStream(
destinationFile);
int bufferSize;
byte[] bufffer = new byte[512];
while ((bufferSize = fileInputStream.read(bufffer)) > 0) {
fileOutputStream.write(bufffer, 0, bufferSize);
}
fileInputStream.close();
fileOutputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}

The NIO classes make this pretty simple.
http://www.javalobby.org/java/forums/t17036.html

Use
org.apache.commons.io.FileUtils
It's so handy

i use the following code to transfer a uploaded CommonMultipartFile to a folder and copy that file to a destination folder in webapps (i.e) web project folder,
String resourcepath = "C:/resources/images/" + commonsMultipartFile.getOriginalFilename();
File file = new File(resourcepath);
commonsMultipartFile.transferTo(file);
//Copy File to a Destination folder
File destinationDir = new File("C:/Tomcat/webapps/myProject/resources/images/");
FileUtils.copyFileToDirectory(file, destinationDir);

Copy file from one directory to another directory...
FileChannel source=new FileInputStream(new File("source file path")).getChannel();
FileChannel desti=new FileOutputStream(new File("destination file path")).getChannel();
desti.transferFrom(source, 0, source.size());
source.close();
desti.close();

here is simply a java code to copy data from one folder to another, you have to just give the input of the source and destination.
import java.io.*;
public class CopyData {
static String source;
static String des;
static void dr(File fl,boolean first) throws IOException
{
if(fl.isDirectory())
{
createDir(fl.getPath(),first);
File flist[]=fl.listFiles();
for(int i=0;i<flist.length;i++)
{
if(flist[i].isDirectory())
{
dr(flist[i],false);
}
else
{
copyData(flist[i].getPath());
}
}
}
else
{
copyData(fl.getPath());
}
}
private static void copyData(String name) throws IOException {
int i;
String str=des;
for(i=source.length();i<name.length();i++)
{
str=str+name.charAt(i);
}
System.out.println(str);
FileInputStream fis=new FileInputStream(name);
FileOutputStream fos=new FileOutputStream(str);
byte[] buffer = new byte[1024];
int noOfBytes = 0;
while ((noOfBytes = fis.read(buffer)) != -1) {
fos.write(buffer, 0, noOfBytes);
}
}
private static void createDir(String name, boolean first) {
int i;
if(first==true)
{
for(i=name.length()-1;i>0;i--)
{
if(name.charAt(i)==92)
{
break;
}
}
for(;i<name.length();i++)
{
des=des+name.charAt(i);
}
}
else
{
String str=des;
for(i=source.length();i<name.length();i++)
{
str=str+name.charAt(i);
}
(new File(str)).mkdirs();
}
}
public static void main(String args[]) throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("program to copy data from source to destination \n");
System.out.print("enter source path : ");
source=br.readLine();
System.out.print("enter destination path : ");
des=br.readLine();
long startTime = System.currentTimeMillis();
dr(new File(source),true);
long endTime = System.currentTimeMillis();
long time=endTime-startTime;
System.out.println("\n\n Time taken = "+time+" mili sec");
}
}
this a working code for what you want..let me know if it helped

Best way as per my knowledge is as follows:
public static void main(String[] args) {
String sourceFolder = "E:\\Source";
String targetFolder = "E:\\Target";
File sFile = new File(sourceFolder);
File[] sourceFiles = sFile.listFiles();
for (File fSource : sourceFiles) {
File fTarget = new File(new File(targetFolder), fSource.getName());
copyFileUsingStream(fSource, fTarget);
deleteFiles(fSource);
}
}
private static void deleteFiles(File fSource) {
if(fSource.exists()) {
try {
FileUtils.forceDelete(fSource);
} catch (IOException e) {
e.printStackTrace();
}
}
}
private static void copyFileUsingStream(File source, File dest) {
InputStream is = null;
OutputStream os = null;
try {
is = new FileInputStream(source);
os = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer)) > 0) {
os.write(buffer, 0, length);
}
} catch (Exception ex) {
System.out.println("Unable to copy file:" + ex.getMessage());
} finally {
try {
is.close();
os.close();
} catch (Exception ex) {
}
}
}

You can use the following code to copy files from one directory to another
// parent folders of dest must exist before calling this function
public static void copyTo( File src, File dest ) throws IOException {
// recursively copy all the files of src folder if src is a directory
if( src.isDirectory() ) {
// creating parent folders where source files is to be copied
dest.mkdirs();
for( File sourceChild : src.listFiles() ) {
File destChild = new File( dest, sourceChild.getName() );
copyTo( sourceChild, destChild );
}
}
// copy the source file
else {
InputStream in = new FileInputStream( src );
OutputStream out = new FileOutputStream( dest );
writeThrough( in, out );
in.close();
out.close();
}
}

File file = fileChooser.getSelectedFile();
String selected = fc.getSelectedFile().getAbsolutePath();
File srcDir = new File(selected);
FileInputStream fii;
FileOutputStream fio;
try {
fii = new FileInputStream(srcDir);
fio = new FileOutputStream("C:\\LOvE.txt");
byte [] b=new byte[1024];
int i=0;
try {
while ((fii.read(b)) > 0)
{
System.out.println(b);
fio.write(b);
}
fii.close();
fio.close();

following code to copy files from one directory to another
File destFile = new File(targetDir.getAbsolutePath() + File.separator
+ file.getName());
try {
showMessage("Copying " + file.getName());
in = new BufferedInputStream(new FileInputStream(file));
out = new BufferedOutputStream(new FileOutputStream(destFile));
int n;
while ((n = in.read()) != -1) {
out.write(n);
}
showMessage("Copied " + file.getName());
} catch (Exception e) {
showMessage("Cannot copy file " + file.getAbsolutePath());
} finally {
if (in != null)
try {
in.close();
} catch (Exception e) {
}
if (out != null)
try {
out.close();
} catch (Exception e) {
}
}

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 CopyFiles {
private File targetFolder;
private int noOfFiles;
public void copyDirectory(File sourceLocation, String destLocation)
throws IOException {
targetFolder = new File(destLocation);
if (sourceLocation.isDirectory()) {
if (!targetFolder.exists()) {
targetFolder.mkdir();
}
String[] children = sourceLocation.list();
for (int i = 0; i < children.length; i++) {
copyDirectory(new File(sourceLocation, children[i]),
destLocation);
}
} else {
InputStream in = new FileInputStream(sourceLocation);
OutputStream out = new FileOutputStream(targetFolder + "\\"+ sourceLocation.getName(), true);
System.out.println("Destination Path ::"+targetFolder + "\\"+ sourceLocation.getName());
// Copy the bits from instream to outstream
byte[] buf = new byte[1024];
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
in.close();
out.close();
noOfFiles++;
}
}
public static void main(String[] args) throws IOException {
File srcFolder = new File("C:\\sourceLocation\\");
String destFolder = new String("C:\\targetLocation\\");
CopyFiles cf = new CopyFiles();
cf.copyDirectory(srcFolder, destFolder);
System.out.println("No Of Files got Retrieved from Source ::"+cf.noOfFiles);
System.out.println("Successfully Retrieved");
}
}

Not even that complicated and no imports required in Java 7:
The renameTo( ) method changes the name of a file:
public boolean renameTo( File destination)
For example, to change the name of the file src.txt in the current working directory to dst.txt, you would write:
File src = new File(" src.txt"); File dst = new File(" dst.txt"); src.renameTo( dst);
That's it.
Reference:
Harold, Elliotte Rusty (2006-05-16). Java I/O (p. 393). O'Reilly Media. Kindle Edition.

You can use the following code to copy files from one directory to another
public static void copyFile(File sourceFile, File destFile) throws IOException {
InputStream in = null;
OutputStream out = null;
try {
in = new FileInputStream(sourceFile);
out = new FileOutputStream(destFile);
byte[] buffer = new byte[1024];
int length;
while ((length = in.read(buffer)) > 0) {
out.write(buffer, 0, length);
}
} catch(Exception e){
e.printStackTrace();
}
finally {
in.close();
out.close();
}
}

Following recursive function I have written, if it helps anyone. It will copy all the files inside sourcedirectory to destinationDirectory.
example:
rfunction("D:/MyDirectory", "D:/MyDirectoryNew", "D:/MyDirectory");
public static void rfunction(String sourcePath, String destinationPath, String currentPath) {
File file = new File(currentPath);
FileInputStream fi = null;
FileOutputStream fo = null;
if (file.isDirectory()) {
String[] fileFolderNamesArray = file.list();
File folderDes = new File(destinationPath);
if (!folderDes.exists()) {
folderDes.mkdirs();
}
for (String fileFolderName : fileFolderNamesArray) {
rfunction(sourcePath, destinationPath + "/" + fileFolderName, currentPath + "/" + fileFolderName);
}
} else {
try {
File destinationFile = new File(destinationPath);
fi = new FileInputStream(file);
fo = new FileOutputStream(destinationPath);
byte[] buffer = new byte[1024];
int ind = 0;
while ((ind = fi.read(buffer))>0) {
fo.write(buffer, 0, ind);
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally {
if (null != fi) {
try {
fi.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (null != fo) {
try {
fo.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}