- Type Parameters:
- T- The type of element returned by the iterator
- All Superinterfaces:
- AutoCloseable,- Closeable,- Iterable<T>
- All Known Subinterfaces:
- SecureDirectoryStream<T>
  While DirectoryStream extends Iterable, it is not a
 general-purpose Iterable as it supports only a single 
 Iterator; invoking the iterator method to obtain a second
 or subsequent iterator throws IllegalStateException. 
 
 An important property of the directory stream's Iterator is that
 its hasNext method is guaranteed to read-ahead by
 at least one element. If hasNext method returns true, and is
 followed by a call to the next method, it is guaranteed that the
 next method will not throw an exception due to an I/O error, or
 because the stream has been closed. The Iterator does
 not support the remove operation.
 
 A DirectoryStream is opened upon creation and is closed by
 invoking the close method. Closing a directory stream releases any
 resources associated with the stream. Failure to close the stream may result
 in a resource leak. The try-with-resources statement provides a useful
 construct to ensure that the stream is closed:
 
    Path dir = ...
    try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir)) {
        for (Path entry: stream) {
            ...
        }
    }
 Once a directory stream is closed, then further access to the directory,
 using the Iterator, behaves as if the end of stream has been reached.
 Due to read-ahead, the Iterator may return one or more elements
 after the directory stream has been closed. Once these buffered elements
 have been read, then subsequent calls to the hasNext method return
 false, and subsequent calls to the next method will throw
 NoSuchElementException.
 
 A directory stream is not required to be asynchronously closeable.
 If a thread is blocked on the directory stream's iterator reading from the
 directory, and another thread invokes the close method, then the
 second thread may block until the read operation is complete.
 
 If an I/O error is encountered when accessing the directory then it
 causes the Iterator's hasNext or next methods to
 throw DirectoryIteratorException with the IOException as the
 cause. As stated above, the hasNext method is guaranteed to
 read-ahead by at least one element. This means that if hasNext method
 returns true, and is followed by a call to the next method,
 then it is guaranteed that the next method will not fail with a
 DirectoryIteratorException.
 
The elements returned by the iterator are in no specific order. Some file systems maintain special links to the directory itself and the directory's parent directory. Entries representing these links are not returned by the iterator.
 The iterator is weakly consistent. It is thread safe but does not
 freeze the directory while iterating, so it may (or may not) reflect updates
 to the directory that occur after the DirectoryStream is created.
 
Usage Examples: Suppose we want a list of the source files in a directory. This example uses both the for-each and try-with-resources constructs.
    List<Path> listSourceFiles(Path dir) throws IOException {
        List<Path> result = new ArrayList<>();
        try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir, "*.{c,h,cpp,hpp,java}")) {
            for (Path entry: stream) {
                result.add(entry);
            }
        } catch (DirectoryIteratorException ex) {
            // I/O error encountered during the iteration, the cause is an IOException
            throw ex.getCause();
        }
        return result;
    }
- Since:
- 1.7
- See Also:
- 
Nested Class SummaryNested ClassesModifier and TypeInterfaceDescriptionstatic interfaceAn interface that is implemented by objects that decide if a directory entry should be accepted or filtered.
- 
Method SummaryMethods declared in interface java.lang.IterableforEach, spliterator
- 
Method Details- 
iteratorReturns the iterator associated with thisDirectoryStream.- Specified by:
- iteratorin interface- Iterable<T>
- Returns:
- the iterator associated with this DirectoryStream
- Throws:
- IllegalStateException- if this directory stream is closed or the iterator has already been returned
 
 
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