1 /*
2 * Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.nio.file;
27
28 import java.util.Iterator;
29 import java.io.Closeable;
30 import java.io.IOException;
31
32 /**
33 * An object to iterate over the entries in a directory. A directory stream
34 * allows for the convenient use of the for-each construct to iterate over a
35 * directory.
36 *
37 * <p> <b> While {@code DirectoryStream} extends {@code Iterable}, it is not a
38 * general-purpose {@code Iterable} as it supports only a single {@code
39 * Iterator}; invoking the {@link #iterator iterator} method to obtain a second
40 * or subsequent iterator throws {@code IllegalStateException}. </b>
41 *
42 * <p> An important property of the directory stream's {@code Iterator} is that
43 * its {@link Iterator#hasNext() hasNext} method is guaranteed to read-ahead by
44 * at least one element. If {@code hasNext} method returns {@code true}, and is
45 * followed by a call to the {@code next} method, it is guaranteed that the
46 * {@code next} method will not throw an exception due to an I/O error, or
47 * because the stream has been {@link #close closed}. The {@code Iterator} does
48 * not support the {@link Iterator#remove remove} operation.
49 *
50 * <p> A {@code DirectoryStream} is opened upon creation and is closed by
51 * invoking the {@code close} method. Closing a directory stream releases any
52 * resources associated with the stream. Failure to close the stream may result
53 * in a resource leak. The try-with-resources statement provides a useful
54 * construct to ensure that the stream is closed:
55 * <pre>
56 * Path dir = ...
57 * try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir)) {
58 * for (Path entry: stream) {
59 * ...
60 * }
100 * List<Path> result = new ArrayList<>();
101 * try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir, "*.{c,h,cpp,hpp,java}")) {
102 * for (Path entry: stream) {
103 * result.add(entry);
104 * }
105 * } catch (DirectoryIteratorException ex) {
106 * // I/O error encounted during the iteration, the cause is an IOException
107 * throw ex.getCause();
108 * }
109 * return result;
110 * }
111 * </pre>
112 * @param <T> The type of element returned by the iterator
113 *
114 * @since 1.7
115 *
116 * @see Files#newDirectoryStream(Path)
117 */
118
119 public interface DirectoryStream<T>
120 extends Closeable, Iterable<T> {
121 /**
122 * An interface that is implemented by objects that decide if a directory
123 * entry should be accepted or filtered. A {@code Filter} is passed as the
124 * parameter to the {@link Files#newDirectoryStream(Path,DirectoryStream.Filter)}
125 * method when opening a directory to iterate over the entries in the
126 * directory.
127 *
128 * @param <T> the type of the directory entry
129 *
130 * @since 1.7
131 */
132 @FunctionalInterface
133 public static interface Filter<T> {
134 /**
135 * Decides if the given directory entry should be accepted or filtered.
136 *
137 * @param entry
138 * the directory entry to be tested
139 *
140 * @return {@code true} if the directory entry should be accepted
|
1 /*
2 * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.nio.file;
27
28 import java.util.Iterator;
29 import java.io.Closeable;
30 import java.io.IOException;
31
32 /**
33 * An object to iterate over the entries in a directory. A directory stream
34 * allows for the convenient use of the for-each construct to iterate over a
35 * directory.
36 *
37 * <p> {@code DirectoryStream} extends {@code IterableOnce}. It is not a
38 * general-purpose {@code Iterable} as it supports only a single {@code
39 * Iterator}; invoking the {@link #iterator iterator} method to obtain a second
40 * or subsequent iterator throws {@code IllegalStateException}.
41 *
42 * <p> An important property of the directory stream's {@code Iterator} is that
43 * its {@link Iterator#hasNext() hasNext} method is guaranteed to read-ahead by
44 * at least one element. If {@code hasNext} method returns {@code true}, and is
45 * followed by a call to the {@code next} method, it is guaranteed that the
46 * {@code next} method will not throw an exception due to an I/O error, or
47 * because the stream has been {@link #close closed}. The {@code Iterator} does
48 * not support the {@link Iterator#remove remove} operation.
49 *
50 * <p> A {@code DirectoryStream} is opened upon creation and is closed by
51 * invoking the {@code close} method. Closing a directory stream releases any
52 * resources associated with the stream. Failure to close the stream may result
53 * in a resource leak. The try-with-resources statement provides a useful
54 * construct to ensure that the stream is closed:
55 * <pre>
56 * Path dir = ...
57 * try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir)) {
58 * for (Path entry: stream) {
59 * ...
60 * }
100 * List<Path> result = new ArrayList<>();
101 * try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir, "*.{c,h,cpp,hpp,java}")) {
102 * for (Path entry: stream) {
103 * result.add(entry);
104 * }
105 * } catch (DirectoryIteratorException ex) {
106 * // I/O error encounted during the iteration, the cause is an IOException
107 * throw ex.getCause();
108 * }
109 * return result;
110 * }
111 * </pre>
112 * @param <T> The type of element returned by the iterator
113 *
114 * @since 1.7
115 *
116 * @see Files#newDirectoryStream(Path)
117 */
118
119 public interface DirectoryStream<T>
120 extends Closeable, IterableOnce<T> {
121 /**
122 * An interface that is implemented by objects that decide if a directory
123 * entry should be accepted or filtered. A {@code Filter} is passed as the
124 * parameter to the {@link Files#newDirectoryStream(Path,DirectoryStream.Filter)}
125 * method when opening a directory to iterate over the entries in the
126 * directory.
127 *
128 * @param <T> the type of the directory entry
129 *
130 * @since 1.7
131 */
132 @FunctionalInterface
133 public static interface Filter<T> {
134 /**
135 * Decides if the given directory entry should be accepted or filtered.
136 *
137 * @param entry
138 * the directory entry to be tested
139 *
140 * @return {@code true} if the directory entry should be accepted
|