/**@class java.nio.file.DirectoryStream implements java.io.Closeable implements java.lang.Iterable An object to iterate over the entries in a directory. A directory stream allows for the convenient use of the for-each construct to iterate over a directory. <p> <b> While {@code DirectoryStream} extends {@code Iterable}, it is not a general-purpose {@code Iterable} as it supports only a single {@code Iterator}; invoking the {@link #iterator iterator} method to obtain a second or subsequent iterator throws {@code IllegalStateException}. </b> <p> An important property of the directory stream's {@code Iterator} is that its {@link Iterator#hasNext() hasNext} method is guaranteed to read-ahead by at least one element. If {@code hasNext} method returns {@code true}, and is followed by a call to the {@code next} method, it is guaranteed that the {@code next} method will not throw an exception due to an I/O error, or because the stream has been {@link #close closed}. The {@code Iterator} does not support the {@link Iterator#remove remove} operation. <p> A {@code DirectoryStream} is opened upon creation and is closed by invoking the {@code 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: <pre> Path dir = ... try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir)) { for (Path entry: stream) { ... } } </pre> <p> Once a directory stream is closed, then further access to the directory, using the {@code Iterator}, behaves as if the end of stream has been reached. Due to read-ahead, the {@code 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 {@code hasNext} method returns {@code false}, and subsequent calls to the {@code next} method will throw {@code NoSuchElementException}. <p> A directory stream is not required to be <i>asynchronously closeable</i>. If a thread is blocked on the directory stream's iterator reading from the directory, and another thread invokes the {@code close} method, then the second thread may block until the read operation is complete. <p> If an I/O error is encountered when accessing the directory then it causes the {@code Iterator}'s {@code hasNext} or {@code next} methods to throw {@link java.nio.file.DirectoryIteratorException} with the {@link IOException} as the cause. As stated above, the {@code hasNext} method is guaranteed to read-ahead by at least one element. This means that if {@code hasNext} method returns {@code true}, and is followed by a call to the {@code next} method, then it is guaranteed that the {@code next} method will not fail with a {@code DirectoryIteratorException}. <p> 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. <p> The iterator is <i>weakly consistent</i>. 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 {@code DirectoryStream} is created. <p> <b>Usage Examples:</b> Suppose we want a list of the source files in a directory. This example uses both the for-each and try-with-resources constructs. <pre> 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 encounted during the iteration, the cause is an IOException throw ex.getCause(); } return result; } </pre> @param <T> The type of element returned by the iterator @since 1.7 @see Files#newDirectoryStream(Path) */ var DirectoryStream = { /**Returns the iterator associated with this {@code DirectoryStream}. @return {Object {java.util.Iterator}} the iterator associated with this {@code DirectoryStream} @throws IllegalStateException if this directory stream is closed or the iterator has already been returned */ iterator : function( ) {}, };