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How to copy lines from a text file to another text file? [duplicate]

I want to copy a file from one location to another location in Java. What is the best way to do this?
Here is what I have so far:
import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.List;
public class TestArrayList {
public static void main(String[] args) {
File f = new File(
"D:\\CBSE_Demo\\Demo_original\\fscommand\\contentplayer\\config");
List<String>temp=new ArrayList<String>();
temp.add(0, "N33");
temp.add(1, "N1417");
temp.add(2, "N331");
File[] matchingFiles = null;
for(final String temp1: temp){
matchingFiles = f.listFiles(new FilenameFilter() {
public boolean accept(File dir, String name) {
return name.startsWith(temp1);
}
});
System.out.println("size>>--"+matchingFiles.length);
}
}
}
This does not copy the file, what is the best way to do this?

You can use this (or any variant):
Files.copy(src, dst, StandardCopyOption.REPLACE_EXISTING);
Also, I'd recommend using File.separator or / instead of \\ to make it compliant across multiple OS, question/answer on this available here.
Since you're not sure how to temporarily store files, take a look at ArrayList:
List<File> files = new ArrayList();
files.add(foundFile);
To move a List of files into a single directory:
List<File> files = ...;
String path = "C:/destination/";
for(File file : files) {
Files.copy(file.toPath(),
(new File(path + file.getName())).toPath(),
StandardCopyOption.REPLACE_EXISTING);
}

Update:
see also
https://stackoverflow.com/a/67179064/1847899
Using Stream
private static void copyFileUsingStream(File source, File dest) throws IOException {
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);
}
} finally {
is.close();
os.close();
}
}
Using Channel
private static void copyFileUsingChannel(File source, File dest) throws IOException {
FileChannel sourceChannel = null;
FileChannel destChannel = null;
try {
sourceChannel = new FileInputStream(source).getChannel();
destChannel = new FileOutputStream(dest).getChannel();
destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
}finally{
sourceChannel.close();
destChannel.close();
}
}
Using Apache Commons IO lib:
private static void copyFileUsingApacheCommonsIO(File source, File dest) throws IOException {
FileUtils.copyFile(source, dest);
}
Using Java SE 7 Files class:
private static void copyFileUsingJava7Files(File source, File dest) throws IOException {
Files.copy(source.toPath(), dest.toPath());
}
Or try Googles Guava :
https://github.com/google/guava
docs:
https://guava.dev/releases/snapshot-jre/api/docs/com/google/common/io/Files.html

Use the New Java File classes in Java >=7.
Create the below method and import the necessary libs.
public static void copyFile( File from, File to ) throws IOException {
Files.copy( from.toPath(), to.toPath() );
}
Use the created method as below within main:
File dirFrom = new File(fileFrom);
File dirTo = new File(fileTo);
try {
copyFile(dirFrom, dirTo);
} catch (IOException ex) {
Logger.getLogger(TestJava8.class.getName()).log(Level.SEVERE, null, ex);
}
NB:- fileFrom is the file that you want to copy to a new file fileTo in a different folder.
Credits - #Scott: Standard concise way to copy a file in Java?

public static void copyFile(File oldLocation, File newLocation) throws IOException {
if ( oldLocation.exists( )) {
BufferedInputStream reader = new BufferedInputStream( new FileInputStream(oldLocation) );
BufferedOutputStream writer = new BufferedOutputStream( new FileOutputStream(newLocation, false));
try {
byte[] buff = new byte[8192];
int numChars;
while ( (numChars = reader.read( buff, 0, buff.length ) ) != -1) {
writer.write( buff, 0, numChars );
}
} catch( IOException ex ) {
throw new IOException("IOException when transferring " + oldLocation.getPath() + " to " + newLocation.getPath());
} finally {
try {
if ( reader != null ){
writer.close();
reader.close();
}
} catch( IOException ex ){
Log.e(TAG, "Error closing files when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}
} else {
throw new IOException("Old location does not exist when transferring " + oldLocation.getPath() + " to " + newLocation.getPath() );
}
}

Copy a file from one location to another location means,need to copy the whole content to another location.Files.copy(Path source, Path target, CopyOption... options) throws IOException this method expects source location which is original file location and target location which is a new folder location with destination same type file(as original).
Either Target location needs to exist in our system otherwise we need to create a folder location and then in that folder location we need to create a file with the same name as original filename.Then using copy function we can easily copy a file from one location to other.
public static void main(String[] args) throws IOException {
String destFolderPath = "D:/TestFile/abc";
String fileName = "pqr.xlsx";
String sourceFilePath= "D:/TestFile/xyz.xlsx";
File f = new File(destFolderPath);
if(f.mkdir()){
System.out.println("Directory created!!!!");
}
else {
System.out.println("Directory Exists!!!!");
}
f= new File(destFolderPath,fileName);
if(f.createNewFile()) {
System.out.println("File Created!!!!");
} else {
System.out.println("File exists!!!!");
}
Files.copy(Paths.get(sourceFilePath), Paths.get(destFolderPath, fileName),REPLACE_EXISTING);
System.out.println("Copy done!!!!!!!!!!!!!!");
}

You can do it with the Java 8 Streaming API, PrintWriter and the Files API
try (PrintWriter pw = new PrintWriter(new File("destination-path"), StandardCharsets.UTF_8)) {
Files.readAllLines(Path.of("src/test/resources/source-file.something"), StandardCharsets.UTF_8)
.forEach(pw::println);
}
If you want to modify the content on-the-fly while copying, check out this link for the extended example https://overflowed.dev/blog/copy-file-and-modify-with-java-streams/

I modified one of the answers to make it a bit more efficient.
public void copy(){
InputStream in = null;
try {
in = new FileInputStream(Files);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
try {
OutputStream out = new FileOutputStream();
try {
// Transfer bytes from in to out
byte[] buf = new byte[1024];
while (true) {
int len = 0;
try {
if (!((len = in.read(buf)) > 0)) break;
} catch (IOException e) {
e.printStackTrace();
}
try {
out.write(buf, 0, len);
} catch (IOException e) {
e.printStackTrace();
}
}
} finally {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
} finally {
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void moveFile() {
copy();
File dir = getFilesDir();
File file = new File(dir, "my_filename");
boolean deleted = file.delete();
}

Files.exists()
Files.createDirectory()
Files.copy()
Overwriting Existing Files:
Files.move()
Files.delete()
Files.walkFileTree()
enter link description here

You can use
FileUtils.copy(sourceFile, destinationFile);
https://commons.apache.org/proper/commons-io/apidocs/org/apache/commons/io/FileUtils.html

obtain force lock on file using java used by other process in windows

I wanted to Override a file which is used by other process in windows machine using Java Program, for which I want obtain force lock on file , please guide me how can I achieve.
I am using org.apache.commons.io.monitor.FileAlterationObserver to check whether file is changed or not if changed i want to override dest file with src file.
I tried both code snippets I am getting below exception.
Exception :
The process cannot access the file because it is being used by another process
at java.io.RandomAccessFile.open(Native Method)
Code Snippet1
FileAlterationObserver observer = new FileAlterationObserver(folderToObserve);
observer.addListener(new FileAlterationListener() {
#Override
public void onFileChange(File file) {
System.out.println("File changed , file.getAbsolutePath() : "+file.getAbsolutePath());
file.delete();
try {
FileUtils.copyFile(srcFile, file);
//checkAndUpdateFile(srcFile, file);
} catch (Exception e) {
System.out.println("Error In overriding file");
e.printStackTrace();
}
}
Code Snippet2
private static void checkAndUpdateFile(File src, File dest) throws IOException {
FileInputStream in = new FileInputStream(src);
FileChannel srcChannel = in.getChannel();
FileChannel destChannel = null;
FileLock destLock = null;
try {
if (!dest.exists()) {
final RandomAccessFile destFile = new RandomAccessFile(dest, "rw");
destChannel = destFile.getChannel();
destLock = destChannel.lock();
copyFileChannels(srcChannel, destChannel);
dest.setLastModified(src.lastModified());
} else {
final RandomAccessFile destFile = new RandomAccessFile(dest, "rw");
destChannel = destFile.getChannel();
destLock = destChannel.lock();
if (!compareFileChannels(srcChannel, destChannel)) {
copyFileChannels(srcChannel, destChannel);
dest.setLastModified(src.lastModified());
}
}
}

How to write a database to a text file in android

I am working on a Spying application for my college project purpose. For that i have logged the Calls, Location and SMS of the device and stored them in a database. Now i want to export the contents of the database to a text file.. I tried the below code.
private void readAndWriteCallsData() {
File dataBaseFile = getDatabasePath("DATABASE");
File callDataFile = new File(Environment.getDataDirectory()+"/data/com.example.myapp/databases/"+"DATABASE");
try {
BufferedReader dbFileReader = new BufferedReader(new FileReader(callDataFile));
String eachLine;
while((eachLine = dbFileReader.readLine()) != null)
{
Callslog.append(eachLine);
Callslog.append("\n");
}
} catch (IOException e) {
e.printStackTrace();
}
}
But that is not working... Please help me...

You can encode the database file from binary stream to character stream by Base64, then decode the text when nessesary.
First find a Base64 library. You can use http://sourceforge.net/projects/iharder/files/base64/. There's only one file, "Base64.java".
Code example:
private void readAndWriteCallsData() {
File callDataFile = new File(Environment.getDataDirectory()+"/data/com.example.myapp/databases/"+"DATABASE");
try {
FileInputStream fis = new FileInputStream(callDataFile);
try{
byte[] buf = new byte[512];
int len;
while((len = fis.read(buf)) > 0){
String text = Base64.encodeBytes(buf, 0, len); // encode binary to text
Callslog.append(text);
Callslog.append("\n");
}
}finally{
fis.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
To revert it, code like following:
private void revertCallsData() {
File encodedCallDataFile; // get reference to the encoded text file
try {
BufferedReader br = new BufferedReader(new FileReader(encodedCallDataFile));
try{
String line;
while((line = br.readLine()) != null){
byte[] bin = Base64.decode(line); // decode each line to binary, you can get the original database file
}
}finally{
br.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}

ok guys after a lot of hit and trial i finally found the solution, here is the code, i saved the functionality in a button.
final String SAMPLE_DB_NAME = "MyDBName.db";//database name
save.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
File sd = Environment.getExternalStorageDirectory();
File data = Environment.getDataDirectory();
FileChannel source=null;
FileChannel destination=null;
String currentDBPath = "/data/"+ "your package name" +"/databases/"+SAMPLE_DB_NAME;
String backupDBPath = SAMPLE_DB_NAME;
File currentDB = new File(data, currentDBPath);
File backupDB = new File(sd, backupDBPath);
try {
source = new FileInputStream(currentDB).getChannel();
destination = new FileOutputStream(backupDB).getChannel();
destination.transferFrom(source, 0, source.size());
source.close();
destination.close();
Toast.makeText(getApplicationContext(),"Your database has been exported",
Toast.LENGTH_LONG).show();
} catch(IOException e) {
e.printStackTrace();
}
}
});
the database will be saved in /storage/emulated/0/

I would recommend to export into a structered file format such as JSON or CSV. Here is my JSON exporter method. Maybe it helps
private static final String LOG_FOLDER = "/ExportFolder";
private static final String FILE_NAME = "export_file.json";
public static void exportMeasurementsJSON(Handler mHandler) {
sendToastMessage("Export to JSON started", mHandler);
File folder = new File(Environment.getExternalStorageDirectory()
+ LOG_FOLDER);
if (!folder.exists())
folder.mkdir();
final String filename = folder.toString() + "/"
+ getLogFileName(".json");
try {
FileWriter fw = new FileWriter(filename, false /* append */);
// get the db
SomeDateSource db = PIApplication.getDB();
// Google Gson for serializing Java Objects into JSON
Gson mGson = new GsonBuilder().create();
Cursor c = db.getAllRows();
if (c != null) {
while (c.moveToNext()) {
fw.append(mGson.toJson(new DBEntry(c
.getString(1), c.getString(2), c
.getDouble(3), c.getLong(4))));
fw.append('\n');
}
c.close();
}
fw.close();
sendToastMessage("Export finished", mHandler);
} catch (Exception e) {
sendToastMessage("Something went wrong", mHandler);
e.printStackTrace();
}
}
If you're interested I can also add my CSV exporter.

Your question is not that clear (Are you trying to copy the file to an alternative location or export the actual data from it?)
If you only wish to copy the file, you can copy the db file using the following method:
public static void copyFile(String sourceFileFullPath, String destFileFullPath) throws IOException
{
String copyFileCommand = "dd if=" + sourceFileFullPath + " of=" + destFileFullPath;
Runtime.getRuntime().exec(copyFileCommand);
}
Simply call that method with your database file path (/data/data/package_name/databases/database_name) as sourceFileFullPath and your target file path as destFileFullPath. You can than use tools such as SQLite Expert to view the content of the database on your PC/Laptop.
If your intention is to export the data from the database and store it in a text file (a CSV file or anything similar), then you should not read the database file content, and instead use the SQLiteDatabase class to query each table contents into a Cursor and iterate it to write each cursor row into a text file.

You could export the entire db into your sdcard folder and then use SQLite manager to open and see it's content.
A Example is available here: http://www.techrepublic.com/blog/software-engineer/export-sqlite-data-from-your-android-device/

Here is the complete method for writing the Database in the SD Card:
/**
* Copy the app db file into the sd card
*/
private void backupDatabase(Context context) throws IOException {
//Open your local db as the input stream
String inFileName = "/data/data/yourappPackageName/databases/yourDBName.db";
// OR use- context.getFilesDir().getPath()+"/databases/yourDBName.db";//
File dbFile = new File(inFileName);
FileInputStream fis = new FileInputStream(dbFile);
String outFileName = Environment.getExternalStorageDirectory()+"/"+SQLiteDataHelper.DB_NAME;
//Open the empty db as the output stream
OutputStream output = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = fis.read(buffer))>0){
output.write(buffer, 0, length);
}
//Close the streams
output.flush();
output.close();
fis.close();
}
Hope it will help you.

One way to do this (I assume its a long procedure, easy one though), if you know the database and get all the tables and retrieve info from those tables. Since, we are talking about sqlite DBs, I assume it will be small.
SELECT * FROM dbname.sqlite_master WHERE type='table';

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());
}

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();
}
}
}
}
}