Added in [API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Nested Classes](https://developer.android.com/reference/java/nio/file/DirectoryStream#nestedclasses) \| [Methods](https://developer.android.com/reference/java/nio/file/DirectoryStream#pubmethods) \| [Inherited Methods](https://developer.android.com/reference/java/nio/file/DirectoryStream#inhmethods)

# DirectoryStream


`
public


interface
DirectoryStream
`


`


implements

https://developer.android.com/reference/java/io/Closeable,

https://developer.android.com/reference/java/lang/Iterable<T>


`

|---|
| java.nio.file.DirectoryStream\<T\> |

|---|
| Known indirect subclasses [SecureDirectoryStream](https://developer.android.com/reference/java/nio/file/SecureDirectoryStream)\<T\> |---|---| | [SecureDirectoryStream](https://developer.android.com/reference/java/nio/file/SecureDirectoryStream)\<T\> | A `DirectoryStream` that defines operations on files that are located relative to an open directory. | |

<br />

*** ** * ** ***

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.

**While `DirectoryStream` extends `Iterable`, it is not a
general-purpose `Iterable` as it supports only a single `Iterator`; invoking the `https://developer.android.com/reference/java/nio/file/DirectoryStream#iterator()` method to obtain a second
or subsequent iterator throws `IllegalStateException`.**

An important property of the directory stream's `Iterator` is that
its `https://developer.android.com/reference/java/util/Iterator#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 `https://developer.android.com/reference/java/io/Closeable#close()`. The `Iterator` does
not support the `https://developer.android.com/reference/java/util/Iterator#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 returns
`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 `https://developer.android.com/reference/java/nio/file/DirectoryIteratorException` with the `https://developer.android.com/reference/java/io/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 encounted during the iteration, the cause is an IOException
          throw ex.getCause();
      }
      return result;
  }
```

<br />

**See also:**

- `https://developer.android.com/reference/java/nio/file/Files#newDirectoryStream(java.nio.file.Path)`

## Summary

| ### Nested classes ||
|---|---|
| ` interface` | `https://developer.android.com/reference/java/nio/file/DirectoryStream.Filter<T>` An interface that is implemented by objects that decide if a directory entry should be accepted or filtered. |

| ### Public methods ||
|---|---|
| ` abstract https://developer.android.com/reference/java/util/Iterator<T>` | ` https://developer.android.com/reference/java/nio/file/DirectoryStream#iterator()() ` Returns the iterator associated with this `DirectoryStream`. |

| ### Inherited methods |
|---|---|
| From interface ` https://developer.android.com/reference/java/io/Closeable ` |---|---| | ` abstract void` | ` https://developer.android.com/reference/java/io/Closeable#close()() ` Closes this stream and releases any system resources associated with it. | ||
| From interface ` https://developer.android.com/reference/java/lang/Iterable ` |---|---| | ` default void` | ` https://developer.android.com/reference/java/lang/Iterable#forEach(java.util.function.Consumer<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Consumer<? super T> action) ` Performs the given action for each element of the `Iterable` until all elements have been processed or the action throws an exception. | | ` abstract https://developer.android.com/reference/java/util/Iterator<T>` | ` https://developer.android.com/reference/java/lang/Iterable#iterator()() ` Returns an iterator over elements of type `T`. | | ` default https://developer.android.com/reference/java/util/Spliterator<T>` | ` https://developer.android.com/reference/java/lang/Iterable#spliterator()() ` Creates a `https://developer.android.com/reference/java/util/Spliterator` over the elements described by this `Iterable`. | ||
| From interface ` https://developer.android.com/reference/java/lang/AutoCloseable ` |---|---| | ` abstract void` | ` https://developer.android.com/reference/java/lang/AutoCloseable#close()() ` Closes this resource, relinquishing any underlying resources. | ||

## Public methods

### iterator

Added in [API level 26](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public abstract Iterator<T> iterator ()
```

Returns the iterator associated with this `DirectoryStream`.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Iterator<T>` | the iterator associated with this `DirectoryStream` <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalStateException` | if this directory stream is closed or the iterator has already been returned |