问题
I want to delete all files inside ABC directory.
When I tried with FileUtils.deleteDirectory(new File("C:/test/ABC/")); it also deletes folder ABC.
Is there a one liner solution where I can delete files inside directory but not directory?
回答1:
FileUtils.cleanDirectory(directory);
There is this method available in the same file. This will also recursively deletes all sub-folders and files under them.
Docs: org.apache.commons.io.FileUtils.cleanDirectory
回答2:
Do you mean like?
for(File file: dir.listFiles())
if (!file.isDirectory())
file.delete();
This will only delete files, not directories.
回答3:
Peter Lawrey's answer is great because it is simple and not depending on anything special, and it's the way you should do it. If you need something that removes subdirectories and their contents as well, use recursion:
void purgeDirectory(File dir) {
for (File file: dir.listFiles()) {
if (file.isDirectory())
purgeDirectory(file);
file.delete();
}
}
To spare subdirectories and their contents (part of your question), modify as follows:
void purgeDirectoryButKeepSubDirectories(File dir) {
for (File file: dir.listFiles()) {
if (!file.isDirectory())
file.delete();
}
}
Or, since you wanted a one-line solution:
for (File file: dir.listFiles())
if (!file.isDirectory())
file.delete();
Using an external library for such a trivial task is not a good idea unless you need this library for something else anyway, in which case it is preferrable to use existing code. You appear to be using the Apache library anyway so use its FileUtils.cleanDirectory() method.
回答4:
Java 8 Stream
This deletes only files from ABC (sub-directories are untouched):
Arrays.stream(new File("C:/test/ABC/").listFiles()).forEach(File::delete);
This deletes only files from ABC (and sub-directories):
Files.walk(Paths.get("C:/test/ABC/"))
.filter(Files::isRegularFile)
.map(Path::toFile)
.forEach(File::delete);
^ This version requires handling the IOException
回答5:
Or to use this in Java 8:
try {
Files.newDirectoryStream( directory ).forEach( file -> {
try { Files.delete( file ); }
catch ( IOException e ) { throw new UncheckedIOException(e); }
} );
}
catch ( IOException e ) {
e.printStackTrace();
}
It's a pity the exception handling is so bulky, otherwise it would be a one-liner ...
回答6:
public class DeleteFile {
public static void main(String[] args) {
String path="D:\test";
File file = new File(path);
File[] files = file.listFiles();
for (File f:files)
{if (f.isFile() && f.exists)
{ f.delete();
system.out.println("successfully deleted");
}else{
system.out.println("cant delete a file due to open or error");
} } }}
回答7:
Another Java 8 Stream solution to delete all the content of a folder, sub directories included, but not the folder itself.
Usage:
Path folder = Paths.get("/tmp/folder");
CleanFolder.clean(folder);
and the code:
public interface CleanFolder {
static void clean(Path folder) throws IOException {
Function<Path, Stream<Path>> walk = p -> {
try { return Files.walk(p);
} catch (IOException e) {
return Stream.empty();
}};
Consumer<Path> delete = p -> {
try {
Files.delete(p);
} catch (IOException e) {
}
};
Files.list(folder)
.flatMap(walk)
.sorted(Comparator.reverseOrder())
.forEach(delete);
}
}
The problem with every stream solution involving Files.walk or Files.delete is that these methods throws IOException which are a pain to handle in streams.
I tried to create a solution which is more concise as possible.
回答8:
For deleting all files from directory say "C:\Example"
File file = new File("C:\\Example");
String[] myFiles;
if (file.isDirectory()) {
myFiles = file.list();
for (int i = 0; i < myFiles.length; i++) {
File myFile = new File(file, myFiles[i]);
myFile.delete();
}
}
回答9:
package com;
import java.io.File;
public class Delete {
public static void main(String[] args) {
String files;
File file = new File("D:\\del\\yc\\gh");
File[] listOfFiles = file.listFiles();
for (int i = 0; i < listOfFiles.length; i++)
{
if (listOfFiles[i].isFile())
{
files = listOfFiles[i].getName();
System.out.println(files);
if(!files.equalsIgnoreCase("Scan.pdf"))
{
boolean issuccess=new File(listOfFiles[i].toString()).delete();
System.err.println("Deletion Success "+issuccess);
}
}
}
}
}
If you want to delete all files remove
if(!files.equalsIgnoreCase("Scan.pdf"))
statement it will work.
回答10:
rm -rf was much more performant than FileUtils.cleanDirectory.
Not a one-liner solution but after extensive benchmarking, we found that using rm -rf was multiple times faster than using FileUtils.cleanDirectory.
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.cleanDirectory 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 clearDirectory( 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();
file.mkdirs(); // Since we only want to clear the directory and not delete it, we need to re-create the directory.
return true;
}
return false;
}
Worth trying if you're dealing with large or complex directories.
回答11:
I think this will work (based on NonlinearFruit previous answer):
Files.walk(Paths.get("C:/test/ABC/"))
.sorted(Comparator.reverseOrder())
.map(Path::toFile)
.filter(item -> !item.getPath().equals("C:/test/ABC/"))
.forEach(File::delete);
Cheers!
来源：https://stackoverflow.com/questions/13195797/delete-all-files-in-directory-but-not-directory-one-liner-solution