I try to delete a directory using java,here is my code
public static void delDirectory(String path) throws IOException {
Path p = Paths.get(path);
delHelp(p);
}
private static void delHelp(Path p) throws IOException {
if (!p.toFile().exists()) {
return;
} else if(p.toFile().isFile()){
log.debug("delete file:" + p.toAbsolutePath().toString());
Files.delete(p);
}else if(p.toFile().isDirectory()){
for(Path subPath:Files.newDirectoryStream(p)){
delHelp(subPath);
}
log.debug("delete directory:"+p.toAbsolutePath().toString());
Files.delete(p);
}
}
On unix-like system, it works out. On windows, the code Files.delete(p) actually move the directory to the trash can, so when delete the parent directory the code will throw exception: Exception in thread "main" java.nio.file.DirectoryNotEmptyException
Any idea about this os-dependent behavior? How can I work around this?
The actual problem is that you are not closing the DirectoryStream, which is causing the DirectoryNotEmptyException when you try to delete the directory.
From the Javadoc:
When not using the try-with-resources construct, then directory stream's close method should be invoked after iteration is completed so as to free any resources held for the open directory.
So you can either call close() on it when you are done with it, or use it in try-with-resources:
private static void delHelp(Path p) throws IOException {
if (!p.toFile().exists()) {
return;
} else if(p.toFile().isFile()){
Files.delete(p);
} else if(p.toFile().isDirectory()){
try (DirectoryStream<Path> ds = Files.newDirectoryStream(p)) {
for (Path subPath : ds){
delHelp(subPath);
}
}
Files.delete(p);
}
}
please first of all add this Jar into your project first.
Find below code works perfectly as per your requirement too.
i.e. work on window machine and should be not goes to trash/recycle-bin
public static void main(String[] args) {
try {
delDirectory("E:\\RecursiveDataContainDirectoryName");
} catch (Exception e) {
e.printStackTrace();
}
}
public static void delDirectory(String path) throws IOException {
Path p = Paths.get(path);
FileDeleteStrategy.FORCE.delete(p.toFile());
}
Related
I just want to load .jar libraries in my running programm. Therefore i created a "libs" folder in my programm directory.
In the main in call the function loadDependencies() to load all the .jar files in the libs directory to use them in a plugin extension system.
Now the problem, it does not work :)
Here the code i tried so far:
public class DependencyLoader {
private static final Class<?>[] parameters = new Class[]{URL.class};
public static void addFile(String s) throws IOException {
File f = new File(s);
addFile(f);
}
public static void addFile(File f) throws IOException {
addURL(f.toURI().toURL());
}
public static void addURL(URL u) throws IOException {
URLClassLoader sysloader = (URLClassLoader)ClassLoader.getSystemClassLoader();
Class<?> sysclass = URLClassLoader.class;
try {
Method method = sysclass.getDeclaredMethod("addURL",parameters);
method.setAccessible(true);
method.invoke(sysloader,new Object[]{ u });
} catch (Throwable t) {
t.printStackTrace();
throw new IOException("Error, could not add URL to system classloader");
}
}
public static void loadDependencies(){
File libsDir = new File("/home/admin/network/lobby/libs");
if(!libsDir.exists() && !libsDir.mkdirs() && !libsDir.isDirectory()){
System.out.println("could not find lib directory!");
System.exit(-1);
}
for(File file : libsDir.listFiles()){
if(file.getName().endsWith(".jar")){
System.out.println("loading dependency "+file.getName());
try {
addFile(file);
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
The libraries are found . But not loaded correctly. The result is a noclassdef error.
Hope someone can help me.
Regards!
I am creating a rollback feature and here is what I have and wanna achieve:
a tmp folder is created in the same location as the data folder;
before doing any operation I copy all the contents from data folder to tmp folder (small amount of data).
On rollback I want to delete the data folder and rename tmp folder to data folder.
This is what I tried
String contentPath = "c:\\temp\\data";
String tmpContentPath = "c:\\temp\\data.TMP";
if (Files.exists(Paths.get(tmpContentPath)) && Files.list(Paths.get(tmpContentPath)).count() > 0) {
FileUtils.deleteDirectory(new File(contentPath));
Files.move(Paths.get(tmpContentPath), Paths.get(contentPath), java.nio.file.StandardCopyOption.REPLACE_EXISTING);
}
but this throws FileAlreadyExistsException even though I deleted the target directory in the same method.
Once the program exits I don't see the c:\temp\data directory, so the directory is actually deleted.
Now if I try StandardCopyOption.ATOMIC_MOVE it throws an java.nio.file.AccessDeniedException.
What is the best way to move tmp dir to data dir in these kind of situations?
Actually in java 7 or above you can just use the Files to achieve the folder moving even there is a conflict, which means the target folder already exists.
private static void moveFolder(Path thePath, Path targetPath) {
if (Files.exists(targetPath)) { // if the target folder exists, delete it first;
deleteFolder(targetPath);
}
try {
Files.move(thePath, targetPath);
} catch (IOException ignored) {
ignored.printStackTrace();
}
}
private static void deleteFolder(Path path) {
try {
if (Files.isRegularFile(path)) { // delete regular file directly;
Files.delete(path);
return;
}
try (Stream<Path> paths = Files.walk(path)) {
paths.filter(p -> p.compareTo(path) != 0).forEach(p -> deleteFolder(p)); // delete all the children folders or files;
Files.delete(path); // delete the folder itself;
}
} catch (IOException ignored) {
ignored.printStackTrace();
}
}
Try This
public class MoveFolder
{
public static void main(String[] args) throws IOException
{
File sourceFolder = new File("c:\\temp\\data.TMP");
File destinationFolder = new File("c:\\temp\\data");
if (destinationFolder.exists())
{
destinationFolder.delete();
}
copyAllData(sourceFolder, destinationFolder);
}
private static void copyAllData(File sourceFolder, File destinationFolder)
throws IOException
{
destinationFolder.mkdir();
String files[] = sourceFolder.list();
for (String file : files)
{
File srcFile = new File(sourceFolder, file);
File destFile = new File(destinationFolder, file);
copyAllData(srcFile, destFile); //call recursive
}
}
}
Figured out the issue. In my code before doing a rollback, I am doing a backup, in that method I am using this section to do the copy
if (Files.exists(Paths.get(contentPath)) && Files.list(Paths.get(contentPath)).count() > 0) {
copyPath(Paths.get(contentPath), Paths.get(tmpContentPath));
}
Changed it to
try (Stream<Path> fileList = Files.list(Paths.get(contentPath))) {
if (Files.exists(Paths.get(contentPath)) && fileList.count() > 0) {
copyPath(Paths.get(contentPath), Paths.get(tmpContentPath));
}
}
to fix the issue
This question already has an answer here:
java.lang.IllegalStateException: Iterator already obtained
(1 answer)
Closed 7 years ago.
so I wrote a little Java program to test a little stack language I made vie various test file, but for some reason it won't work.
Here is the code:
import org.apache.commons.io.FilenameUtils;
import java.io.IOException;
import java.nio.file.*;
public class Main {
public static void run(DirectoryStream<Path> files) throws IOException {
for (Path f : files) {
String ext = FilenameUtils.getExtension(f.toString());
if (ext.equals("slang")) { // if extension "slang" run program slang with slang test file as argument and dump result int a file with the same base name but .test extension
Runtime.getRuntime().exec("java slang < " + f.getFileName() + " > " + FilenameUtils.getBaseName(f.toString()) + ".test");
}
}
}
public static void main(String[] args) {
try {
Runtime.getRuntime().exec("javac slang.java; "); // compile slang
} catch (IOException e) {
e.printStackTrace();
}
Path dir = Paths.get("C:\\Users\\Anton\\Documents\\TU Wien\\PK\\SS2015\\Abschlussaufgabe\\Slang\\progs");
try { //create list of all Files in test directory Files
DirectoryStream<Path> files = Files.newDirectoryStream(dir);
run(files); //run all needed files
compare(files); //compare all files
} catch (IOException | DirectoryIteratorException x) {
System.err.println(x);
x.printStackTrace();
}
}
public static void compare(DirectoryStream<Path> files) throws IOException {
for (Path f : files) {
String ext = FilenameUtils.getExtension(f.toString()); //is it a test file?
if (ext.equals("test")) {
String outputPath = FilenameUtils.getBaseName(f.toString()) + ".output"; //get path of output
Path output = Paths.get(outputPath);
if (!fileEquals(f, output)) { // compare them
System.err.println("Not Equal:" + f.getFileName()); // errormessage if fault, else just continue
}
}
//files.iterator().remove();
//files.iterator().next();
}
}
private static boolean fileEquals(Path p, Path q) throws IOException {
String contentP = new String(Files.readAllBytes(p)); //turn into string then compare, no idea whether best practice
String contentQ = new String(Files.readAllBytes(q));
return contentP.equals(contentQ);
}
}
When I run it, it throws "Exception in thread "main" java.lang.IllegalStateException: Iterator already obtained".
i already tried it with the iterator().remove and iterator().next, but it only leads to the application running longer before throwing the error.
Thank you for any help beforehand.
Addition: The error occures at the foreach loop through the DirectoryStream.
You have to call DirectoryStream<Path> files = Files.newDirectoryStream(dir); each time you iterate over the files.
Pls check this question...
java.lang.IllegalStateException: Iterator already obtained
I'm trying to find a way to detect when a flash drive has been plugged into my computer. So far, the solution I found was to poll FileSystem#getFileStores for changes. This does indeed tell me when the flash drive has been inserted, but as far as I can tell there is no way to retrieve the location for it. FileStore#type and FileStore#name both seem highly unreliable as their return value is implementation specific, but they appear to be the only methods that might return any relevant information that might help find the directory for the FileStore.
With that in mind, the following code:
public class Test {
public static void main(String[] args) throws IOException {
for (FileStore store : FileSystems.getDefault().getFileStores()) {
System.out.println(store);
System.out.println("\t" + store.name());
System.out.println("\t" + store.type());
System.out.println();
}
}
}
Gave me this output:
/ (/dev/sda5)
/dev/sda5
ext4
/* snip */
/media/TI103426W0D (/dev/sda2)
/dev/sda2
fuseblk
/media/flashdrive (/dev/sdb1)
/dev/sdb1
vfat
As it turns out, FileStore#type returns the format of the drive and FileStore#name returns the location of the device file for the drive. As far as I can tell, the only method which has the location of the drive is the toString method, but extracting the path name out of it seems dangerous because I'm not sure how well that particular solution would hold up on other operating systems and future versions of Java.
Is there something I'm missing here or is this simply not possible purely with Java?
System Information:
$ java -version
java version "1.7.0_03"
OpenJDK Runtime Environment (IcedTea7 2.1.1pre) (7~u3-2.1.1~pre1-1ubuntu2)
OpenJDK Client VM (build 22.0-b10, mixed mode, sharing)
$ uname -a
Linux jeffrey-pc 3.2.0-24-generic-pae #37-Ubuntu SMP Wed Apr 25 10:47:59 UTC 2012 i686 athlon i386 GNU/Linux
Here's a temporary work around until a better solution is found:
public Path getRootPath(FileStore fs) throws IOException {
Path media = Paths.get("/media");
if (media.isAbsolute() && Files.exists(media)) { // Linux
try (DirectoryStream<Path> stream = Files.newDirectoryStream(media)) {
for (Path p : stream) {
if (Files.getFileStore(p).equals(fs)) {
return p;
}
}
}
} else { // Windows
IOException ex = null;
for (Path p : FileSystems.getDefault().getRootDirectories()) {
try {
if (Files.getFileStore(p).equals(fs)) {
return p;
}
} catch (IOException e) {
ex = e;
}
}
if (ex != null) {
throw ex;
}
}
return null;
}
As far as I know, this solution will only work for Windows and Linux systems.
You have to catch the IOException in the Windows loop because if there is no CD in the CD drive an exception is thrown when you try to retrieve the FileStore for it. This might happen before you iterate over every root.
This is what I have ended up doing. This is limited to Windows + UNIX but avoids using external tools or additional library calls. It steals the information Java already has in the FileStore objects
LinuxFileStore definitely extends UnixFileStore, so it will work. Same deal for Solaris. Since Mac OS X is UNIX, it probably works there but I'm not sure because I couldn't see its subclass in any place I was looking.
public class FileStoreHacks {
/**
* Stores the known hacks.
*/
private static final Map<Class<? extends FileStore>, Hacks> hacksMap;
static {
ImmutableMap.Builder<Class<? extends FileStore>, Hacks> builder =
ImmutableMap.builder();
try {
Class<? extends FileStore> fileStoreClass =
Class.forName("sun.nio.fs.WindowsFileStore")
.asSubclass(FileStore.class);
builder.put(fileStoreClass, new WindowsFileStoreHacks(fileStoreClass));
} catch (ClassNotFoundException e) {
// Probably not running on Windows.
}
try {
Class<? extends FileStore> fileStoreClass =
Class.forName("sun.nio.fs.UnixFileStore")
.asSubclass(FileStore.class);
builder.put(fileStoreClass, new UnixFileStoreHacks(fileStoreClass));
} catch (ClassNotFoundException e) {
// Probably not running on UNIX.
}
hacksMap = builder.build();
}
private FileStoreHacks() {
}
/**
* Gets the path from a file store. For some reason, NIO2 only has a method
* to go in the other direction.
*
* #param store the file store.
* #return the path.
*/
public static Path getPath(FileStore store) {
Hacks hacks = hacksMap.get(store.getClass());
if (hacks == null) {
return null;
} else {
return hacks.getPath(store);
}
}
private static interface Hacks {
Path getPath(FileStore store);
}
private static class WindowsFileStoreHacks implements Hacks {
private final Field field;
public WindowsFileStoreHacks(Class<?> fileStoreClass) {
try {
field = fileStoreClass.getDeclaredField("root");
field.setAccessible(true);
} catch (NoSuchFieldException e) {
throw new IllegalStateException("file field not found", e);
}
}
#Override
public Path getPath(FileStore store) {
try {
String root = (String) field.get(store);
return FileSystems.getDefault().getPath(root);
} catch (IllegalAccessException e) {
throw new IllegalStateException("Denied access", e);
}
}
}
private static class UnixFileStoreHacks implements Hacks {
private final Field field;
private UnixFileStoreHacks(Class<?> fileStoreClass) {
try {
field = fileStoreClass.getDeclaredField("file");
field.setAccessible(true);
} catch (NoSuchFieldException e) {
throw new IllegalStateException("file field not found", e);
}
}
#Override
public Path getPath(FileStore store) {
try {
return (Path) field.get(store);
} catch (IllegalAccessException e) {
throw new IllegalStateException("Denied access", e);
}
}
}
}
I've not really explored this area of java, but I found this, which seems to be related. It uses File.listRoots()
There also seems to be a number of related questions linked there too.
This works for Windows:
public Path getFileStoreRootPath(FileStore fs) throws Exception {
for (Path root : FileSystems.getDefault().getRootDirectories()) {
if (Files.isDirectory(root) && Files.getFileStore(root).equals(fs)) {
return root;
}
}
throw new RuntimeException("Root directory for filestore " + fs + " not found");
}
Basically, by filtering by condition Files.isDirectory(root) we are excluding all CD/DVD drives which will throw IOException when compact-disc is not inserted.
I need to write a recursive algorithm to display the contents of a directory in a computer's file system but I am very new to Java. Does anyone have any code or a good tutorial on how to access a directory in a file system with Java??
You can use the JFileChooser class, check this example.
Optionally you can also execute native commands like DIR , lsusing java , here is an example
This took me way too long to write and test, but here's something that should work.
Note: You can pass in either a string or file.
Note 2: This is a naive implementation. Not only is it single-threaded, but it does not check to see if files are links, and could get stuck in an endless loop due to this.
Note 3: The lines immediately after comments can be replaced with your own implementation.
import java.io.*;
public class DirectoryRecurser {
public static void parseFile(String filePath) throws FileNotFoundException {
File file = new File(filePath);
if (file.exists()) {
parseFile(file);
} else {
throw new FileNotFoundException(file.getPath());
}
}
public static void parseFile(File file) throws FileNotFoundException {
if (file.isDirectory()) {
for(File child : file.listFiles()) {
parseFile(child);
}
} else if (file.exists()) {
// Process file here
System.out.println(file.getPath());
} else {
throw new FileNotFoundException(file.getPath());
}
}
}
Which could then be called something like this (using a Windows path, because this Workstation is using Windows):
public static void main(String[] args) {
try {
DirectoryRecurser.parseFile("D:\\raisin");
} catch (FileNotFoundException e) {
// Error handling here
System.out.println("File not found: " + e.getMessage());
}
}
In my case, this prints out:
File not found: D:\raisin
because said directory is just one I made up. Otherwise, it prints out the path to each file.
Check out Apache Commons VFS: http://commons.apache.org/vfs/
Sample:
// Locate the Jar file
FileSystemManager fsManager = VFS.getManager();
FileObject jarFile = fsManager.resolveFile( "jar:lib/aJarFile.jar" );
// List the children of the Jar file
FileObject[] children = jarFile.getChildren();
System.out.println( "Children of " + jarFile.getName().getURI() );
for ( int i = 0; i < children.length; i++ )
{
System.out.println( children[ i ].getName().getBaseName() );
}
If you need to access files on a network drive, check out JCIFS: http://jcifs.samba.org/
check this out buddy
http://java2s.com/Code/Java/File-Input-Output/Traversingallfilesanddirectoriesunderdir.htm
public class Main {
public static void main(String[] argv) throws Exception {
}
public static void visitAllDirsAndFiles(File dir) {
System.out.println(dir);
if (dir.isDirectory()) {
String[] children = dir.list();
for (int i = 0; i < children.length; i++) {
visitAllDirsAndFiles(new File(dir, children[i]));
}
}
}
}
For each file you need to check if it is a directory. If it is, you need to recurse. Here is some untested code, which should help:
public void listFiles(File f){
System.out.println(f.getAbsolutePath());
if(f.isDirectory()){
for (File i : f.listFiles()){
listFiles(i);
}
}
}