I'm trying to produce file listing of a given directory and it's sub directories in a ftp server.
The server works fine, and I have been successfully able to produce the file listing of the current directory. When I try to list the subdirectories and their files is where it gets complicated.
I was asked not to use a recursion algorithm, so I did some research of my own. I have tried using threads (for every directory found, start a new thread), but I wasn't able to keep my connection stable and open. Any ideas on how to do so correctly with threads, or other alternatives?
EDIT: below is my code, when using the recursive statement (last line of code), it works
class TEST {
public static synchronized void main(String[] args) {
String server = args[0]; //server,path will be given as an arguments
String pass = "SOMEPASS";
String user = "SOMEUSER";
int port = 21;
FTPClient ftpClient = new FTPClient();
try {
ftpClient.connect(server, port);
showServerReply(ftpClient);
int replyCode = ftpClient.getReplyCode();
if (!FTPReply.isPositiveCompletion(replyCode)) {
System.out.println("Connect failed");
return;
}
boolean success = ftpClient.login(user, pass);
showServerReply(ftpClient);
if (!success) {
System.out.println("Could not login to the server");
return;
}
/*START THE FILE LISTING HERE*/
} catch (IOException ex) {
System.out.println("Oops! Something wrong happened");
ex.printStackTrace();
} finally {
// logs out and disconnects from server
try {
if (ftpClient.isConnected()) {
ftpClient.logout();
ftpClient.disconnect();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
private static void showServerReply(FTPClient ftpClient) {
String[] replies = ftpClient.getReplyStrings();
if (replies != null && replies.length > 0) {
for (String aReply : replies) {
System.out.println("SERVER: " + aReply);
}
}
}
private static void scanDir(FTPClient client, String path) throws IOException {
FTPFile[] files = client.listFiles(path); // Search all the files in the current directory
for (int j = 0; j < files.length; j++) {
System.out.println(files[j].getName()); // Print the name of each files
}
FTPFile[] directories = client.listDirectories(path); // Search all the directories in the current directory
for (int i = 0; i < directories.length; i++) {
String dirPath = directories[i].getName();
System.out.println(dirPath); // Print the path of a sub-directory
scanDir(client,dirPath); // Call recursively the method to display the files in the sub-directory DONT WANT TO DO THAT...
}
}
}
Okay, here is an example of how to handle it non-recursively, but with lists.
Mind, that this example is based on /accessing the local filesystem, but can easily be rewritten/extended for any kind of hierarchial/recursive structure.
package stackoverflow.nonrecursivefilesearch;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.stream.Stream;
public class NonRecursiveFileSearch {
public static void main(final String[] args) throws IOException {
final File searchDir = new File("D:\\test\\maven-test"); // set one
System.out.println("\nOld Java");
printDirs(listFiles_old(searchDir, true, true), "OLD: Depth first, include dirs");
printDirs(listFiles_old(searchDir, true, false), "OLD: Breadth first, include dirs");
printDirs(listFiles_old(searchDir, false, true), "OLD: Depth first, exclude dirs");
printDirs(listFiles_old(searchDir, false, false), "OLD: Breadth first, exclude dirs");
System.out.println("\nNew java.io with streams");
printDirs(listFiles_newIO(searchDir, true), "Java NIO, include dirs");
printDirs(listFiles_newIO(searchDir, false), "Java NIO, exclude dirs");
}
/**
* this is the way to 'manually' find files in hierarchial/recursive structures
*
* reminder: "Depth First" is not a real depth-first implementation
* real depth-first would iterate subdirs immediately.
* this implementation iterates breadth first, but descends into supdirs before it handles same-level directories
* advantage of this implementation is its speed, no need for additional lists etc.
*
* in case you want to exclude recursion traps made possible by symbolic or hard links, you could introduce a hashset/treeset with
* visited files (use filename strings retrieved with canonicalpath).
* in the loop, check if the current canonical filename string is contained in the hash/treeset
*/
static public ArrayList<File> listFiles_old(final File pDir, final boolean pIncludeDirectories, final boolean pDepthFirst) {
final ArrayList<File> found = new ArrayList<>();
final ArrayList<File> todo = new ArrayList<>();
todo.add(pDir);
while (todo.size() > 0) {
final int removeIndex = pDepthFirst ? todo.size() - 1 : 0;
final File currentDir = todo.remove(removeIndex);
if (currentDir == null || !currentDir.isDirectory()) continue;
final File[] files = currentDir.listFiles();
for (final File file : files) {
if (file.isDirectory()) {
if (pIncludeDirectories) found.add(file);
// additional directory filters go here
todo.add(file);
} else {
// additional file filters go here
found.add(file);
}
}
}
return found;
}
static private void printDirs(final ArrayList<File> pFiles, final String pTitle) {
System.out.println("====================== " + pTitle + " ======================");
for (int i = 0; i < pFiles.size(); i++) {
final File file = pFiles.get(i);
System.out.println(i + "\t" + file.getAbsolutePath());
}
System.out.println("============================================================");
}
/**
* this is the java.nio approach. this is NOT be a good solution for cases where you have to retrieve/handle files in your own code.
* this is only useful, if the any NIO class provides support. in this case, NIO class java.nio.file.Files helps handling local files.
* if NIO or your target system does not offer such helper methods, this way is harder to implement, as you have to set up the helper method yourself.
*/
static public Stream<Path> listFiles_newIO(final File pDir, final boolean pIncludeDirectories) throws IOException {
final Stream<Path> stream = Files.find(pDir.toPath(), 100,
(path, basicFileAttributes) -> {
final File file = path.toFile(); // conversion to File for easier access (f.e. isDirectory()), could also use NIO methods
return (pIncludeDirectories || !file.isDirectory() /* additional filters go here */ );
});
return stream;
}
static private void printDirs(final Stream<Path> pStream, final String pTitle) {
System.out.println("====================== " + pTitle + " ======================");
pStream.forEach(System.out::println);
System.out.println("============================================================");
}
}
AND, one must add, java.nio.file.Files.find() might be implemented recursively. But as it's just one call, this maybe could count as 'non-recursive' too.
ALSO, as the OP stated in comments, one might use Stack or other FIFO/LIFO collections. LIFO for a mixed depth-first, FIFO for breadth-first approach.
Currently I am trying to update an old project.
The problem is, that in one of my sources (bungeecord) they have changed two fileds (see enum "protocol") from public final to final modifier. To make the project work again I need to access these two fields.
As a reason of this I try to "inject" the project. This works great, so the modifier changes but I am currently not able to save it to the jar file. But this is necessary.
The process of saving works perfectly for the "userconnection" (see enum below). In this case I edit a class modifier.
If you need any more Information please let me know.
When the "injection" (enum: protocol) is done and I check the modifier type of these fileds I see that there have been some changes.
But when I restart the system and check the filed modifiers again before the "injection" they are as there were no changes.
public static int inject(InjectionType type) {
try{
System.out.println("Starting injection.");
System.out.println(type.getInfo());
ClassPool cp = ClassPool.getDefault();
CtClass clazz = cp.getCtClass(type.getClazz().getName());
switch (type) {
case USERCONNECTION:
int modifier = UserConnection.class.getModifiers();
if (!Modifier.isFinal(modifier) && Modifier.isPublic(modifier)) {
return -1;
}
clazz.setModifiers(Modifier.PUBLIC);
break;
case PROTOCOL:
CtField field = clazz.getField("TO_CLIENT");
field.setModifiers(Modifier.PUBLIC + Modifier.FINAL);
field = clazz.getField("TO_SERVER");
field.setModifiers(Modifier.PUBLIC + Modifier.FINAL);
break;
default:
return -1; //no data
}
ByteArrayOutputStream bout;
DataOutputStream out = new DataOutputStream(bout = new ByteArrayOutputStream());
clazz.getClassFile().write(out);
InputStream[] streams = { new ByteArrayInputStream(bout.toByteArray()) };
File bungee_file = new File(BungeeCord.class.getProtectionDomain().getCodeSource().getLocation().toURI().getPath());
updateZipFile(bungee_file, type, streams);
return 1;
}catch (Exception e){
e.printStackTrace();
}
return 0;
}
private static void updateZipFile(File zipFile, InjectionType type, InputStream[] ins) throws IOException {
File tempFile = File.createTempFile(zipFile.getName(), null);
if (!tempFile.delete()) {
System.out.println("Warn: Cant delete temp file.");
}
if (tempFile.exists()) {
System.out.println("Warn: Temp target file alredy exist!");
}
if (!zipFile.exists()) {
throw new RuntimeException("Could not rename the file " + zipFile.getAbsolutePath() + " to " + tempFile.getAbsolutePath() + " (Src. not found!)");
}
int renameOk = zipFile.renameTo(tempFile) ? 1 : 0;
if (renameOk == 0) {
tempFile = new File(zipFile.toString() + ".copy");
com.google.common.io.Files.copy(zipFile, tempFile);
renameOk = 2;
if (zipFile.delete()) {
System.out.println("Warn: Src file cant delete.");
renameOk = -1;
}
}
if (renameOk == 0) {
throw new RuntimeException("Could not rename the file " + zipFile.getAbsolutePath() + " to " + tempFile.getAbsolutePath() + " (Directory read only? (Temp:[R:" + (tempFile.canRead() ? 1 : 0) + ";W:" + (tempFile.canWrite() ? 1 : 0) + ",D:" + (tempFile.canExecute() ? 1 : 0) + "],Src:[R:" + (zipFile.canRead() ? 1 : 0) + ";W:" + (zipFile.canWrite() ? 1 : 0) + ",D:" + (zipFile.canExecute() ? 1 : 0) + "]))");
}
if (renameOk != 1) {
System.out.println("Warn: Cant create temp file. Use .copy file");
}
byte[] buf = new byte[Configuration.getLoadingBufferSize()];
System.out.println("Buffer size: " + buf.length);
ZipInputStream zin = new ZipInputStream(new FileInputStream(tempFile));
ZipOutputStream out = new ZipOutputStream(new FileOutputStream(zipFile));
ZipEntry entry = zin.getNextEntry();
while (entry != null) {
String path_name = entry.getName().replaceAll("/", "\\.");
boolean notReplace = true;
for (String f : type.getNames()) {
if (f.equals(path_name)) {
notReplace = false;
break;
}
}
if (notReplace) {
out.putNextEntry(new ZipEntry(entry.getName()));
int len;
while ((len = zin.read(buf)) > 0) {
out.write(buf, 0, len);
}
}
entry = zin.getNextEntry();
}
zin.close();
for (int i = 0; i < type.getNames().length; i++) {
InputStream in = ins[i];
int index = type.getNames()[i].lastIndexOf('.');
out.putNextEntry(new ZipEntry(type.getNames()[i].substring(0, index).replaceAll("\\.", "/") + type.getNames()[i].substring(index)));
int len;
while ((len = in.read(buf)) > 0) {
out.write(buf, 0, len);
}
out.closeEntry();
in.close();
}
out.close();
tempFile.delete();
if (renameOk == -1) {
System.exit(-1);
}
}
}
#Getter
public enum InjectionType {
USERCONNECTION(UserConnection.class, new String[] {"net.md_5.bungee.UserConnection.class"}, "Set modifiers for class UserConnection.class to \"public\""),
PROTOCOL(Protocol.class, new String[] {"net.md_5.bungee.protocol.Protocol"}, "Set modifiers for class Protocol.class to \"public\"");
private Class<?> clazz;
private String[] names;
private String info;
InjectionType (Class<?> clazz, String[] names, String info) {
this.clazz = clazz;
this.names = names;
this.info = info;
}
}
When the "injection" (enum: protocol) is done and I check the modifier type of these fileds I see that there have been some changes. But when I restart the system and check the filed modifiers again before the "injection" they are as there were no changes.
What you're trying to do is permanently modify field's access in a jar file using Java reflection. This cannot work as reflection modifies things in runtime only:
Reflection is an API which is used to examine or modify the behavior of methods, classes, interfaces at runtime.
Excerpt taken from this page.
What you need to do is physically edit the jar itself if you want the changes to be permanent. I know you said that you are not able to do that, but as far as I know that is the only possible way. The file itself has to be physically changed if you want the changes to stick after the application has terminated and be applied before the program has started.
Read the official documentation about Java reflection here.
However I don't really understand why is it important that the changes persists after you've restarted the system. The reason you need to change the access is so you can access and perhaps manipulate the class in some way during runtime. What you are doing is correct, one of the more important apsects of reflection is to manipulate data without actually having to modify the physical files themselves and end up using custom distributions.
EDIT: Read this question, it's comments and the accepted answer. They pretty much say the same thing that you can't edit a jar file that is currently being used by JVM, it's locked in a read-only state.
My problem is not How to make a copy of a File in Android, My problem is why it fails to make a copy.
After my app downloads a file am trying to copy it to another folder (The end user can save the file in several folder, that why i download once and copy to the rest). I do have the origin file path like:
/storage/emulated/0/MyAppFolder/FolderCreatedByUser1/theFile.pdf
And am trying to copy it to
/storage/emulated/0/MyAppFolder/FolderCreatedByUser2/
With this code (Code improved by Robert Nekic):
public static boolean copyFile(File src, File[] dst) {
boolean result = true;
if (src.exists()) {
String srcName = src.getName();
for (File file : dst) {
String to = file.getPath();
try {
File destination = new File(to, srcName);
if (destination.createNewFile()) {
FileChannel srcChnl = new FileInputStream(src).getChannel();
FileChannel dstChnl = new FileOutputStream(destination).getChannel();
dstChnl.transferFrom(srcChnl, 0, srcChnl.size());
srcChnl.close();
dstChnl.close();
} else {
result = false;
System.out.println("Unable to create destination " + destination.getPath());
}
} catch (Exception e) {
result = false;
System.out.println(e.getMessage());
break;
}
}
} else {
result = false;
System.out.println("File " + src.getPath() + " doesn't exist.");
}
return result;
}
The file exist, but am keep getting errors when copying it to the destiny file like:
/storage/emulated/0/MyAppFolder/FolderCreatedByUser2/theFile.pdf: open failed: ENOENT (No such file or directory)
It fails in both streams, when trying to open the src file and/or destination file:
FileChannel srcChnl = new FileInputStream(src).getChannel();
FileChannel dstChnl = new FileOutputStream(destination).getChannel();
Permission to write are granted. The destination folders are created previously to the download of the file, the user can't select a destination if the directory isn't created.
destination = new File(to, srcName); creates a new File instance but does not create the underlying file. You can verify by checking destination.exists(). I believe all you need is:
destination = new File(to, srcName);
destination.createNewFile();
Also, your src path string manipulation and stuff in the first half of your code seems unnecessary and might be introducing an error that could be resolved with something more concise:
public static boolean copyFile(File src, File[] dst) {
boolean result = true;
if (src.exists()) {
String srcName = src.getName();
for (File file : dst) {
String to = file.getPath();
try {
File destination = new File(to, srcName);
if (destination.createNewFile()) {
FileChannel srcChnl = new FileInputStream(src).getChannel();
FileChannel dstChnl = new FileOutputStream(destination).getChannel();
dstChnl.transferFrom(srcChnl, 0, srcChnl.size());
srcChnl.close();
dstChnl.close();
} else {
result = false;
System.out.println("Unable to create destination " + destination.getPath());
}
} catch (Exception e) {
result = false;
System.out.println(e.getMessage());
break;
}
}
} else {
result = false;
System.out.println("File " + src.getPath() + " doesn't exist.");
}
return result;
}
I have this section of code:
public static void delete(File f) throws IOException
{
if (f.isDirectory())
{
for (File c : f.listFiles())
{
delete(c);
}
}
else if (!f.delete())
{
throw new FileNotFoundException("Failed to delete file: " + f);
}
}
public static void traverseDelete(File directory) throws FileNotFoundException, InterruptedException
{
//Get all files in directory
File[] files = directory.listFiles();
for (File file : files)
{
if (file.getName().equalsIgnoreCase("word"))
{
boolean containsMedia = false;
File[] filesInWordFolder = file.listFiles();
for ( File file2 : filesInWordFolder )
{
if ( file2.getName().contains("media"))
{
containsMedia = true;
break;
}
}
if (containsMedia == false)
{
try
{
delete(file.getParentFile());
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
else if (file.isDirectory())
{
traverseDelete(file);
}
}
}
Sorry for the lack of commenting, but it's pretty self-explanatory, I think. Essentially what the code is supposed to do is traverses a set of files in a given directory, if it encounters a directory named "word", then it should list out the contents of word, and then if a directory called "media" does NOT exist, recursively delete everything within the parent directory of "word" down.
My main concern comes from this conditional:
if(!filesInWordFolder.toString().contains("media"))
Is that the correct way to say if the files in that array does not contain an instance of "image", go ahead and delete?
That won't work.
File[] filesInWordFolder = file.listFiles();
if(!filesInWordFolder.toString().contains("media"))
will give you a string representation of a File array -- which will typically have a reference.
You have to iterate through the files to find out if there's any in there that contain the word media.
boolean containsMedia = false;
for ( File file : filesInWordFolder ) {
if ( file.getName().contains("media") ){
containsMedia = true;
break;
}
// now check your boolean
if ( !containsMedia ) {
Well using toString() will give you a String representation of the file (in this case the files). The String representation should contain the file name. If your set purpose is to check for any instance of a file containing the word "media" in the directory, you are fine.
In the example you are printing the String representation of the File array. Instead you should iterate through the File array and check the String representation of each individual File as so:
for (int i = 0; i < file_array.length; i++) {
if ((File)file_array[i]).toString().equals("your_search_term")) {
// The file contains your search term
} else {
// Doesn't contain the search term.
}
}
Is there a way to delete entire directories recursively in Java?
In the normal case it is possible to delete an empty directory.
However when it comes to deleting entire directories with contents, it is not that simple anymore.
How do you delete entire directories with contents in Java?
You should check out Apache's commons-io. It has a FileUtils class that will do what you want.
FileUtils.deleteDirectory(new File("directory"));
With Java 7, we can finally do this with reliable symlink detection. (I don't consider Apache's commons-io to have reliable symlink detection at this time, as it doesn't handle links on Windows created with mklink.)
For the sake of history, here's a pre-Java 7 answer, which follows symlinks.
void delete(File f) throws IOException {
if (f.isDirectory()) {
for (File c : f.listFiles())
delete(c);
}
if (!f.delete())
throw new FileNotFoundException("Failed to delete file: " + f);
}
In Java 7+ you can use Files class. Code is very simple:
Path directory = Paths.get("/tmp");
Files.walkFileTree(directory, new SimpleFileVisitor<Path>() {
#Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
Files.delete(file);
return FileVisitResult.CONTINUE;
}
#Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
Files.delete(dir);
return FileVisitResult.CONTINUE;
}
});
One-liner solution (Java8) to delete all files and directories recursively including starting directory:
try (var dirStream = Files.walk(Paths.get("c:/dir_to_delete/"))) {
dirStream
.map(Path::toFile)
.sorted(Comparator.reverseOrder())
.forEach(File::delete);
}
We use a comparator for reversed order, otherwise File::delete won't be able to delete possibly non-empty directory. So, if you want to keep directories and only delete files just remove the comparator in sorted() or remove sorting completely and add files filter:
try (var dirStream = Files.walk(Paths.get("c:/dir_to_delete/"))) {
dirStream
.filter(Files::isRegularFile)
.map(Path::toFile)
.forEach(File::delete);
}
Java 7 added support for walking directories with symlink handling:
import java.nio.file.*;
public static void removeRecursive(Path path) throws IOException
{
Files.walkFileTree(path, new SimpleFileVisitor<Path>()
{
#Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
throws IOException
{
Files.delete(file);
return FileVisitResult.CONTINUE;
}
#Override
public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException
{
// try to delete the file anyway, even if its attributes
// could not be read, since delete-only access is
// theoretically possible
Files.delete(file);
return FileVisitResult.CONTINUE;
}
#Override
public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException
{
if (exc == null)
{
Files.delete(dir);
return FileVisitResult.CONTINUE;
}
else
{
// directory iteration failed; propagate exception
throw exc;
}
}
});
}
I use this as a fallback from platform-specific methods (in this untested code):
public static void removeDirectory(Path directory) throws IOException
{
// does nothing if non-existent
if (Files.exists(directory))
{
try
{
// prefer OS-dependent directory removal tool
if (SystemUtils.IS_OS_WINDOWS)
Processes.execute("%ComSpec%", "/C", "RD /S /Q \"" + directory + '"');
else if (SystemUtils.IS_OS_UNIX)
Processes.execute("/bin/rm", "-rf", directory.toString());
}
catch (ProcessExecutionException | InterruptedException e)
{
// fallback to internal implementation on error
}
if (Files.exists(directory))
removeRecursive(directory);
}
}
(SystemUtils is from Apache Commons Lang. Processes is private but its behavior should be obvious.)
Just saw my solution is more or less the same as erickson's, just packaged as a static method. Drop this somewhere, it's much lighter weight than installing all of Apache Commons for something that (as you can see) is quite simple.
public class FileUtils {
/**
* By default File#delete fails for non-empty directories, it works like "rm".
* We need something a little more brutual - this does the equivalent of "rm -r"
* #param path Root File Path
* #return true iff the file and all sub files/directories have been removed
* #throws FileNotFoundException
*/
public static boolean deleteRecursive(File path) throws FileNotFoundException{
if (!path.exists()) throw new FileNotFoundException(path.getAbsolutePath());
boolean ret = true;
if (path.isDirectory()){
for (File f : path.listFiles()){
ret = ret && deleteRecursive(f);
}
}
return ret && path.delete();
}
}
A solution with a stack and without recursive methods:
File dir = new File("/path/to/dir");
File[] currList;
Stack<File> stack = new Stack<File>();
stack.push(dir);
while (! stack.isEmpty()) {
if (stack.lastElement().isDirectory()) {
currList = stack.lastElement().listFiles();
if (currList.length > 0) {
for (File curr: currList) {
stack.push(curr);
}
} else {
stack.pop().delete();
}
} else {
stack.pop().delete();
}
}
If you have Spring, you can use FileSystemUtils.deleteRecursively:
import org.springframework.util.FileSystemUtils;
boolean success = FileSystemUtils.deleteRecursively(new File("directory"));
Guava had Files.deleteRecursively(File) supported until Guava 9.
From Guava 10:
Deprecated. This method suffers from poor symlink detection and race conditions. This functionality can be supported suitably only by shelling out to an operating system command such as rm -rf or del /s. This method is scheduled to be removed from Guava in Guava release 11.0.
Therefore, there is no such method in Guava 11.
for(Path p : Files.walk(directoryToDelete).
sorted((a, b) -> b.compareTo(a)). // reverse; files before dirs
toArray(Path[]::new))
{
Files.delete(p);
}
Or if you want to handle the IOException:
Files.walk(directoryToDelete).
sorted((a, b) -> b.compareTo(a)). // reverse; files before dirs
forEach(p -> {
try { Files.delete(p); }
catch(IOException e) { /* ... */ }
});
public void deleteRecursive(File path){
File[] c = path.listFiles();
System.out.println("Cleaning out folder:" + path.toString());
for (File file : c){
if (file.isDirectory()){
System.out.println("Deleting file:" + file.toString());
deleteRecursive(file);
file.delete();
} else {
file.delete();
}
}
path.delete();
}
public static void deleteDirectory(File path)
{
if (path == null)
return;
if (path.exists())
{
for(File f : path.listFiles())
{
if(f.isDirectory())
{
deleteDirectory(f);
f.delete();
}
else
{
f.delete();
}
}
path.delete();
}
}
Two ways to fail with symlinks and the above code... and don't know the solution.
Way #1
Run this to create a test:
echo test > testfile
mkdir dirtodelete
ln -s badlink dirtodelete/badlinktodelete
Here you see your test file and test directory:
$ ls testfile dirtodelete
testfile
dirtodelete:
linktodelete
Then run your commons-io deleteDirectory(). It crashes saying the file is not found. Not sure what the other examples do here. The Linux rm command would simply delete the link, and rm -r on the directory would also.
Exception in thread "main" java.io.FileNotFoundException: File does not exist: /tmp/dirtodelete/linktodelete
Way #2
Run this to create a test:
mkdir testdir
echo test > testdir/testfile
mkdir dirtodelete
ln -s ../testdir dirtodelete/dirlinktodelete
Here you see your test file and test directory:
$ ls dirtodelete testdir
dirtodelete:
dirlinktodelete
testdir:
testfile
Then run your commons-io deleteDirectory() or the example code people posted. It deletes not only the directory, but your testfile which is outside the directory being deleted. (It dereferences the directory implicitly, and deletes the contents). rm -r would delete the link only. You need to use something like this delete the dereferenced files: "find -L dirtodelete -type f -exec rm {} \;".
$ ls dirtodelete testdir
ls: cannot access dirtodelete: No such file or directory
testdir:
You could use:
org.apache.commons.io.FileUtils.deleteQuietly(destFile);
Deletes a file, never throwing an exception. If file is a directory, delete it and all sub-directories.
The difference between File.delete() and this method are:
A directory to be deleted does not have to be empty.
No exceptions are thrown when a file or directory cannot be deleted.
An optimal solution that handles exception consistently with the approach that an exception thrown from a method should always describe what that method was trying (and failed) to do:
private void deleteRecursive(File f) throws Exception {
try {
if (f.isDirectory()) {
for (File c : f.listFiles()) {
deleteRecursive(c);
}
}
if (!f.delete()) {
throw new Exception("Delete command returned false for file: " + f);
}
}
catch (Exception e) {
throw new Exception("Failed to delete the folder: " + f, e);
}
}
In legacy projects, I need to create native Java code. I create this code similar to Paulitex code. See that:
public class FileHelper {
public static boolean delete(File fileOrFolder) {
boolean result = true;
if(fileOrFolder.isDirectory()) {
for (File file : fileOrFolder.listFiles()) {
result = result && delete(file);
}
}
result = result && fileOrFolder.delete();
return result;
}
}
And the unit test:
public class FileHelperTest {
#Before
public void setup() throws IOException {
new File("FOLDER_TO_DELETE/SUBFOLDER").mkdirs();
new File("FOLDER_TO_DELETE/SUBFOLDER_TWO").mkdirs();
new File("FOLDER_TO_DELETE/SUBFOLDER_TWO/TEST_FILE.txt").createNewFile();
}
#Test
public void deleteFolderWithFiles() {
File folderToDelete = new File("FOLDER_TO_DELETE");
Assert.assertTrue(FileHelper.delete(folderToDelete));
Assert.assertFalse(new File("FOLDER_TO_DELETE").exists());
}
}
Below code recursively delete all contents in a given folder.
boolean deleteDirectory(File directoryToBeDeleted) {
File[] allContents = directoryToBeDeleted.listFiles();
if (allContents != null) {
for (File file : allContents) {
deleteDirectory(file);
}
}
return directoryToBeDeleted.delete();
}
Here is a bare bones main method that accepts a command line argument, you may need to append your own error checking or mold it to how you see fit.
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
public class DeleteFiles {
/**
* #param intitial arguments take in a source to read from and a
* destination to read to
*/
public static void main(String[] args)
throws FileNotFoundException,IOException {
File src = new File(args[0]);
if (!src.exists() ) {
System.out.println("FAILURE!");
}else{
// Gathers files in directory
File[] a = src.listFiles();
for (int i = 0; i < a.length; i++) {
//Sends files to recursive deletion method
fileDelete(a[i]);
}
// Deletes original source folder
src.delete();
System.out.println("Success!");
}
}
/**
* #param srcFile Source file to examine
* #throws FileNotFoundException if File not found
* #throws IOException if File not found
*/
private static void fileDelete(File srcFile)
throws FileNotFoundException, IOException {
// Checks if file is a directory
if (srcFile.isDirectory()) {
//Gathers files in directory
File[] b = srcFile.listFiles();
for (int i = 0; i < b.length; i++) {
//Recursively deletes all files and sub-directories
fileDelete(b[i]);
}
// Deletes original sub-directory file
srcFile.delete();
} else {
srcFile.delete();
}
}
}
I hope that helps!
Guava provides a one-liner: MoreFiles.deleteRecursively().
Unlike many of the examples shared, it accounts for symbolic links and will not (by default) delete files outside the provided path.
Maybe a solution for this problem might be to reimplement the delete method of the File class using the code from erickson's answer:
public class MyFile extends File {
... <- copy constructor
public boolean delete() {
if (f.isDirectory()) {
for (File c : f.listFiles()) {
return new MyFile(c).delete();
}
} else {
return f.delete();
}
}
}
Without Commons IO and < Java SE 7
public static void deleteRecursive(File path){
path.listFiles(new FileFilter() {
#Override
public boolean accept(File pathname) {
if (pathname.isDirectory()) {
pathname.listFiles(this);
pathname.delete();
} else {
pathname.delete();
}
return false;
}
});
path.delete();
}
rm -rf was much more performant than FileUtils.deleteDirectory.
After extensive benchmarking, we found that using rm -rf was multiple times faster than using FileUtils.deleteDirectory.
Of course, if you have a small or simple directory, it won't matter but in our case we had multiple gigabytes and deeply nested sub directories where it would take over 10 minutes with FileUtils.deleteDirectory and only 1 minute with rm -rf.
Here's our rough Java implementation to do that:
// Delete directory given and all subdirectories and files (i.e. recursively).
//
static public boolean deleteDirectory( File file ) throws IOException, InterruptedException {
if ( file.exists() ) {
String deleteCommand = "rm -rf " + file.getAbsolutePath();
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec( deleteCommand );
process.waitFor();
return true;
}
return false;
}
Worth trying if you're dealing with large or complex directories.
// Java 8 with lambda & stream, if param is directory
static boolean delRecursive(File dir) {
return Arrays.stream(dir.listFiles()).allMatch((f) -> f.isDirectory() ? delRecursive(f) : f.delete()) && dir.delete();
}
// if param is file or directory
static boolean delRecursive(File fileOrDir) {
return fileOrDir.isDirectory() ? Arrays.stream(fileOrDir.listFiles()).allMatch((f) -> delRecursive(f)) && fileOrDir.delete() : fileOrDir.delete();
}
Guava 21.0 and later
There is the void deleteRecursively(Path path, RecursiveDeleteOption... options) throws IOException static method of the MoreFiles class available since Guava 21.0.
Please, see the Javadoc documentation:
public static void deleteRecursively(Path path,
RecursiveDeleteOption... options)
throws IOException
Deletes the file or directory at the given path recursively. Deletes symbolic links, not their targets (subject to the caveat below).
If an I/O exception occurs attempting to read, open or delete any file under the given directory, this method skips that file and continues. All such exceptions are collected and, after attempting to delete all files, an IOException is thrown containing those exceptions as suppressed exceptions.
While files can easily be deleted using file.delete(), directories are required to be empty to be deleted. Use recursion to do this easily. For example:
public static void clearFolders(String[] args) {
for(String st : args){
File folder = new File(st);
if (folder.isDirectory()) {
File[] files = folder.listFiles();
if(files!=null) {
for(File f: files) {
if (f.isDirectory()){
clearFolders(new String[]{f.getAbsolutePath()});
f.delete();
} else {
f.delete();
}
}
}
}
}
}
i coded this routine that has 3 safety criteria for safer use.
package ch.ethz.idsc.queuey.util;
import java.io.File;
import java.io.IOException;
/** recursive file/directory deletion
*
* safety from erroneous use is enhanced by three criteria
* 1) checking the depth of the directory tree T to be deleted
* against a permitted upper bound "max_depth"
* 2) checking the number of files to be deleted #F
* against a permitted upper bound "max_count"
* 3) if deletion of a file or directory fails, the process aborts */
public final class FileDelete {
/** Example: The command
* FileDelete.of(new File("/user/name/myapp/recordings/log20171024"), 2, 1000);
* deletes given directory with sub directories of depth of at most 2,
* and max number of total files less than 1000. No files are deleted
* if directory tree exceeds 2, or total of files exceed 1000.
*
* abort criteria are described at top of class
*
* #param file
* #param max_depth
* #param max_count
* #return
* #throws Exception if criteria are not met */
public static FileDelete of(File file, int max_depth, int max_count) throws IOException {
return new FileDelete(file, max_depth, max_count);
}
// ---
private final File root;
private final int max_depth;
private int removed = 0;
/** #param root file or a directory. If root is a file, the file will be deleted.
* If root is a directory, the directory tree will be deleted.
* #param max_depth of directory visitor
* #param max_count of files to delete
* #throws IOException */
private FileDelete(final File root, final int max_depth, final int max_count) throws IOException {
this.root = root;
this.max_depth = max_depth;
// ---
final int count = visitRecursively(root, 0, false);
if (count <= max_count) // abort criteria 2)
visitRecursively(root, 0, true);
else
throw new IOException("more files to be deleted than allowed (" + max_count + "<=" + count + ") in " + root);
}
private int visitRecursively(final File file, final int depth, final boolean delete) throws IOException {
if (max_depth < depth) // enforce depth limit, abort criteria 1)
throw new IOException("directory tree exceeds permitted depth");
// ---
int count = 0;
if (file.isDirectory()) // if file is a directory, recur
for (File entry : file.listFiles())
count += visitRecursively(entry, depth + 1, delete);
++count; // count file as visited
if (delete) {
final boolean deleted = file.delete();
if (!deleted) // abort criteria 3)
throw new IOException("cannot delete " + file.getAbsolutePath());
++removed;
}
return count;
}
public int deletedCount() {
return removed;
}
public void printNotification() {
int count = deletedCount();
if (0 < count)
System.out.println("deleted " + count + " file(s) in " + root);
}
}