Interface FileVisitor<T>
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- All Known Implementing Classes:
- SimpleFileVisitor
public interface FileVisitor<T>A visitor of files. An implementation of this interface is provided to theFiles.walkFileTreemethods to visit each file in a file tree.Usage Examples: Suppose we want to delete a file tree. In that case, each directory should be deleted after the entries in the directory are deleted.
Path start = ... Files.walkFileTree(start, 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 e) throws IOException { if (e == null) { Files.delete(dir); return FileVisitResult.CONTINUE; } else { // directory iteration failed throw e; } } });Furthermore, suppose we want to copy a file tree to a target location. In that case, symbolic links should be followed and the target directory should be created before the entries in the directory are copied.
final Path source = ... final Path target = ... Files.walkFileTree(source, EnumSet.of(FileVisitOption.FOLLOW_LINKS), Integer.MAX_VALUE, new SimpleFileVisitor<Path>() { @Override public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException { Path targetdir = target.resolve(source.relativize(dir)); try { Files.copy(dir, targetdir); } catch (FileAlreadyExistsException e) { if (!Files.isDirectory(targetdir)) throw e; } return CONTINUE; } @Override public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException { Files.copy(file, target.resolve(source.relativize(file))); return CONTINUE; } });- Since:
- 1.7
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method and Description FileVisitResultpostVisitDirectory(T dir, IOException exc)Invoked for a directory after entries in the directory, and all of their descendants, have been visited.FileVisitResultpreVisitDirectory(T dir, BasicFileAttributes attrs)Invoked for a directory before entries in the directory are visited.FileVisitResultvisitFile(T file, BasicFileAttributes attrs)Invoked for a file in a directory.FileVisitResultvisitFileFailed(T file, IOException exc)Invoked for a file that could not be visited.
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Method Detail
preVisitDirectory
FileVisitResult preVisitDirectory(T dir, BasicFileAttributes attrs) throws IOException
Invoked for a directory before entries in the directory are visited.If this method returns
CONTINUE, then entries in the directory are visited. If this method returnsSKIP_SUBTREEorSKIP_SIBLINGSthen entries in the directory (and any descendants) will not be visited.- Parameters:
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dir- a reference to the directory -
attrs- the directory's basic attributes - Returns:
- the visit result
- Throws:
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IOException- if an I/O error occurs
visitFile
FileVisitResult visitFile(T file, BasicFileAttributes attrs) throws IOException
Invoked for a file in a directory.- Parameters:
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file- a reference to the file -
attrs- the file's basic attributes - Returns:
- the visit result
- Throws:
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IOException- if an I/O error occurs
visitFileFailed
FileVisitResult visitFileFailed(T file, IOException exc) throws IOException
Invoked for a file that could not be visited. This method is invoked if the file's attributes could not be read, the file is a directory that could not be opened, and other reasons.- Parameters:
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file- a reference to the file -
exc- the I/O exception that prevented the file from being visited - Returns:
- the visit result
- Throws:
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IOException- if an I/O error occurs
postVisitDirectory
FileVisitResult postVisitDirectory(T dir, IOException exc) throws IOException
Invoked for a directory after entries in the directory, and all of their descendants, have been visited. This method is also invoked when iteration of the directory completes prematurely (by avisitFilemethod returningSKIP_SIBLINGS, or an I/O error when iterating over the directory).- Parameters:
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dir- a reference to the directory -
exc-nullif the iteration of the directory completes without an error; otherwise the I/O exception that caused the iteration of the directory to complete prematurely - Returns:
- the visit result
- Throws:
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IOException- if an I/O error occurs
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Submit a bug or feature
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