| Known Indirect Subclasses |
A visitor of files. An implementation of this interface is provided to the
Files.walkFileTree methods 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;
}
});
Public Method Summary
| abstract FileVisitResult |
postVisitDirectory(T dir, IOException exc)
Invoked for a directory after entries in the directory, and all of their
descendants, have been visited.
|
| abstract FileVisitResult |
preVisitDirectory(T dir, BasicFileAttributes attrs)
Invoked for a directory before entries in the directory are visited.
|
| abstract FileVisitResult | |
| abstract FileVisitResult |
Public Methods
public abstract FileVisitResult postVisitDirectory (T dir, IOException exc)
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 a visitFile
method returning SKIP_SIBLINGS,
or an I/O error when iterating over the directory).
Parameters
| dir | a reference to the directory |
|---|---|
| exc | null if 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
| IOException | if an I/O error occurs |
|---|
public abstract FileVisitResult preVisitDirectory (T dir, BasicFileAttributes attrs)
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 returns SKIP_SUBTREE or SKIP_SIBLINGS then entries in the
directory (and any descendants) will not be visited.
Parameters
| dir | a reference to the directory |
|---|---|
| attrs | the directory's basic attributes |
Returns
- the visit result
Throws
| IOException | if an I/O error occurs |
|---|
public abstract FileVisitResult visitFile (T file, BasicFileAttributes attrs)
Invoked for a file in a directory.
Parameters
| file | a reference to the file |
|---|---|
| attrs | the file's basic attributes |
Returns
- the visit result
Throws
| IOException | if an I/O error occurs |
|---|
public abstract FileVisitResult visitFileFailed (T file, IOException exc)
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
| file | a reference to the file |
|---|---|
| exc | the I/O exception that prevented the file from being visited |
Returns
- the visit result
Throws
| IOException | if an I/O error occurs |
|---|