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
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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).
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24 */
25
26 package java.nio.file;
27
28 import java.io.File;
29 import java.io.IOException;
30 import java.net.URI;
31 import java.util.Iterator;
32 import java.util.NoSuchElementException;
33
34 /**
35 * An object that may be used to locate a file in a file system. It will
36 * typically represent a system dependent file path.
37 *
38 * <p> A {@code Path} represents a path that is hierarchical and composed of a
39 * sequence of directory and file name elements separated by a special separator
40 * or delimiter. A <em>root component</em>, that identifies a file system
41 * hierarchy, may also be present. The name element that is <em>farthest</em>
42 * from the root of the directory hierarchy is the name of a file or directory.
43 * The other name elements are directory names. A {@code Path} can represent a
44 * root, a root and a sequence of names, or simply one or more name elements.
45 * A {@code Path} is considered to be an <i>empty path</i> if it consists
46 * solely of one name element that is empty. Accessing a file using an
47 * <i>empty path</i> is equivalent to accessing the default directory of the
48 * file system. {@code Path} defines the {@link #getFileName() getFileName},
49 * {@link #getParent getParent}, {@link #getRoot getRoot}, and {@link #subpath
50 * subpath} methods to access the path components or a subsequence of its name
51 * elements.
52 *
53 * <p> In addition to accessing the components of a path, a {@code Path} also
54 * defines the {@link #resolve(Path) resolve} and {@link #resolveSibling(Path)
55 * resolveSibling} methods to combine paths. The {@link #relativize relativize}
56 * method that can be used to construct a relative path between two paths.
57 * Paths can be {@link #compareTo compared}, and tested against each other using
58 * the {@link #startsWith startsWith} and {@link #endsWith endsWith} methods.
59 *
60 * <p> This interface extends {@link Watchable} interface so that a directory
61 * located by a path can be {@link #register registered} with a {@link
62 * WatchService} and entries in the directory watched. </p>
63 *
64 * <p> <b>WARNING:</b> This interface is only intended to be implemented by
65 * those developing custom file system implementations. Methods may be added to
66 * this interface in future releases. </p>
67 *
68 * <h2>Accessing Files</h2>
69 * <p> Paths may be used with the {@link Files} class to operate on files,
70 * directories, and other types of files. For example, suppose we want a {@link
71 * java.io.BufferedReader} to read text from a file "{@code access.log}". The
72 * file is located in a directory "{@code logs}" relative to the current working
73 * directory and is UTF-8 encoded.
74 * <pre>
75 * Path path = FileSystems.getDefault().getPath("logs", "access.log");
76 * BufferedReader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8);
77 * </pre>
78 *
79 * <a name="interop"></a><h2>Interoperability</h2>
80 * <p> Paths associated with the default {@link
81 * java.nio.file.spi.FileSystemProvider provider} are generally interoperable
82 * with the {@link java.io.File java.io.File} class. Paths created by other
83 * providers are unlikely to be interoperable with the abstract path names
84 * represented by {@code java.io.File}. The {@link java.io.File#toPath toPath}
85 * method may be used to obtain a {@code Path} from the abstract path name
86 * represented by a {@code java.io.File} object. The resulting {@code Path} can
87 * be used to operate on the same file as the {@code java.io.File} object. In
88 * addition, the {@link #toFile toFile} method is useful to construct a {@code
89 * File} from the {@code String} representation of a {@code Path}.
90 *
91 * <h2>Concurrency</h2>
92 * <p> Implementations of this interface are immutable and safe for use by
93 * multiple concurrent threads.
94 *
95 * @since 1.7
96 * @see Paths
97 */
98
99 public interface Path
100 extends Comparable<Path>, Iterable<Path>, Watchable
101 {
102 /**
103 * Returns the file system that created this object.
104 *
105 * @return the file system that created this object
106 */
107 FileSystem getFileSystem();
108
109 /**
110 * Tells whether or not this path is absolute.
111 *
112 * <p> An absolute path is complete in that it doesn't need to be combined
113 * with other path information in order to locate a file.
114 *
115 * @return {@code true} if, and only if, this path is absolute
116 */
117 boolean isAbsolute();
118
119 /**
120 * Returns the root component of this path as a {@code Path} object,
121 * or {@code null} if this path does not have a root component.
122 *
123 * @return a path representing the root component of this path,
124 * or {@code null}
125 */
126 Path getRoot();
127
128 /**
129 * Returns the name of the file or directory denoted by this path as a
130 * {@code Path} object. The file name is the <em>farthest</em> element from
131 * the root in the directory hierarchy.
132 *
133 * @return a path representing the name of the file or directory, or
134 * {@code null} if this path has zero elements
135 */
136 Path getFileName();
137
138 /**
139 * Returns the <em>parent path</em>, or {@code null} if this path does not
140 * have a parent.
141 *
142 * <p> The parent of this path object consists of this path's root
143 * component, if any, and each element in the path except for the
144 * <em>farthest</em> from the root in the directory hierarchy. This method
145 * does not access the file system; the path or its parent may not exist.
146 * Furthermore, this method does not eliminate special names such as "."
147 * and ".." that may be used in some implementations. On UNIX for example,
148 * the parent of "{@code /a/b/c}" is "{@code /a/b}", and the parent of
149 * {@code "x/y/.}" is "{@code x/y}". This method may be used with the {@link
150 * #normalize normalize} method, to eliminate redundant names, for cases where
151 * <em>shell-like</em> navigation is required.
152 *
153 * <p> If this path has more than one element, and no root component, then
154 * this method is equivalent to evaluating the expression:
155 * <blockquote><pre>
156 * subpath(0, getNameCount()-1);
157 * </pre></blockquote>
158 *
159 * @return a path representing the path's parent
160 */
161 Path getParent();
162
163 /**
164 * Returns the number of name elements in the path.
165 *
166 * @return the number of elements in the path, or {@code 0} if this path
167 * only represents a root component
168 */
169 int getNameCount();
170
171 /**
172 * Returns a name element of this path as a {@code Path} object.
173 *
174 * <p> The {@code index} parameter is the index of the name element to return.
175 * The element that is <em>closest</em> to the root in the directory hierarchy
176 * has index {@code 0}. The element that is <em>farthest</em> from the root
177 * has index {@link #getNameCount count}{@code -1}.
178 *
179 * @param index
180 * the index of the element
181 *
182 * @return the name element
183 *
184 * @throws IllegalArgumentException
185 * if {@code index} is negative, {@code index} is greater than or
186 * equal to the number of elements, or this path has zero name
187 * elements
188 */
189 Path getName(int index);
190
191 /**
192 * Returns a relative {@code Path} that is a subsequence of the name
193 * elements of this path.
194 *
195 * <p> The {@code beginIndex} and {@code endIndex} parameters specify the
196 * subsequence of name elements. The name that is <em>closest</em> to the root
197 * in the directory hierarchy has index {@code 0}. The name that is
198 * <em>farthest</em> from the root has index {@link #getNameCount
199 * count}{@code -1}. The returned {@code Path} object has the name elements
200 * that begin at {@code beginIndex} and extend to the element at index {@code
201 * endIndex-1}.
202 *
203 * @param beginIndex
204 * the index of the first element, inclusive
205 * @param endIndex
206 * the index of the last element, exclusive
207 *
208 * @return a new {@code Path} object that is a subsequence of the name
209 * elements in this {@code Path}
210 *
211 * @throws IllegalArgumentException
212 * if {@code beginIndex} is negative, or greater than or equal to
213 * the number of elements. If {@code endIndex} is less than or
214 * equal to {@code beginIndex}, or larger than the number of elements.
215 */
216 Path subpath(int beginIndex, int endIndex);
217
218 /**
219 * Tests if this path starts with the given path.
220 *
221 * <p> This path <em>starts</em> with the given path if this path's root
222 * component <em>starts</em> with the root component of the given path,
223 * and this path starts with the same name elements as the given path.
224 * If the given path has more name elements than this path then {@code false}
225 * is returned.
226 *
227 * <p> Whether or not the root component of this path starts with the root
228 * component of the given path is file system specific. If this path does
229 * not have a root component and the given path has a root component then
230 * this path does not start with the given path.
231 *
232 * <p> If the given path is associated with a different {@code FileSystem}
233 * to this path then {@code false} is returned.
234 *
235 * @param other
236 * the given path
237 *
238 * @return {@code true} if this path starts with the given path; otherwise
239 * {@code false}
240 */
241 boolean startsWith(Path other);
242
243 /**
244 * Tests if this path starts with a {@code Path}, constructed by converting
245 * the given path string, in exactly the manner specified by the {@link
246 * #startsWith(Path) startsWith(Path)} method. On UNIX for example, the path
247 * "{@code foo/bar}" starts with "{@code foo}" and "{@code foo/bar}". It
248 * does not start with "{@code f}" or "{@code fo}".
249 *
250 * @implSpec
251 * The default implementation is equivalent for this path to:
252 * <pre>{@code
253 * startsWith(getFileSystem().getPath(other));
254 * }</pre>
255 *
256 * @param other
257 * the given path string
258 *
259 * @return {@code true} if this path starts with the given path; otherwise
260 * {@code false}
261 *
262 * @throws InvalidPathException
263 * If the path string cannot be converted to a Path.
264 */
265 default boolean startsWith(String other) {
266 return startsWith(getFileSystem().getPath(other));
267 }
268
269 /**
270 * Tests if this path ends with the given path.
271 *
272 * <p> If the given path has <em>N</em> elements, and no root component,
273 * and this path has <em>N</em> or more elements, then this path ends with
274 * the given path if the last <em>N</em> elements of each path, starting at
275 * the element farthest from the root, are equal.
276 *
277 * <p> If the given path has a root component then this path ends with the
278 * given path if the root component of this path <em>ends with</em> the root
279 * component of the given path, and the corresponding elements of both paths
280 * are equal. Whether or not the root component of this path ends with the
281 * root component of the given path is file system specific. If this path
282 * does not have a root component and the given path has a root component
283 * then this path does not end with the given path.
284 *
285 * <p> If the given path is associated with a different {@code FileSystem}
286 * to this path then {@code false} is returned.
287 *
288 * @param other
289 * the given path
290 *
291 * @return {@code true} if this path ends with the given path; otherwise
292 * {@code false}
293 */
294 boolean endsWith(Path other);
295
296 /**
297 * Tests if this path ends with a {@code Path}, constructed by converting
298 * the given path string, in exactly the manner specified by the {@link
299 * #endsWith(Path) endsWith(Path)} method. On UNIX for example, the path
300 * "{@code foo/bar}" ends with "{@code foo/bar}" and "{@code bar}". It does
301 * not end with "{@code r}" or "{@code /bar}". Note that trailing separators
302 * are not taken into account, and so invoking this method on the {@code
303 * Path}"{@code foo/bar}" with the {@code String} "{@code bar/}" returns
304 * {@code true}.
305 *
306 * @implSpec
307 * The default implementation is equivalent for this path to:
308 * <pre>{@code
309 * endsWith(getFileSystem().getPath(other));
310 * }</pre>
311 *
312 * @param other
313 * the given path string
314 *
315 * @return {@code true} if this path ends with the given path; otherwise
316 * {@code false}
317 *
318 * @throws InvalidPathException
319 * If the path string cannot be converted to a Path.
320 */
321 default boolean endsWith(String other) {
322 return endsWith(getFileSystem().getPath(other));
323 }
324
325 /**
326 * Returns a path that is this path with redundant name elements eliminated.
327 *
328 * <p> The precise definition of this method is implementation dependent but
329 * in general it derives from this path, a path that does not contain
330 * <em>redundant</em> name elements. In many file systems, the "{@code .}"
331 * and "{@code ..}" are special names used to indicate the current directory
332 * and parent directory. In such file systems all occurrences of "{@code .}"
333 * are considered redundant. If a "{@code ..}" is preceded by a
334 * non-"{@code ..}" name then both names are considered redundant (the
335 * process to identify such names is repeated until it is no longer
336 * applicable).
337 *
338 * <p> This method does not access the file system; the path may not locate
339 * a file that exists. Eliminating "{@code ..}" and a preceding name from a
340 * path may result in the path that locates a different file than the original
341 * path. This can arise when the preceding name is a symbolic link.
342 *
343 * @return the resulting path or this path if it does not contain
344 * redundant name elements; an empty path is returned if this path
345 * does not have a root component and all name elements are redundant
346 *
347 * @see #getParent
348 * @see #toRealPath
349 */
350 Path normalize();
351
352 // -- resolution and relativization --
353
354 /**
355 * Resolve the given path against this path.
356 *
357 * <p> If the {@code other} parameter is an {@link #isAbsolute() absolute}
358 * path then this method trivially returns {@code other}. If {@code other}
359 * is an <i>empty path</i> then this method trivially returns this path.
360 * Otherwise this method considers this path to be a directory and resolves
361 * the given path against this path. In the simplest case, the given path
362 * does not have a {@link #getRoot root} component, in which case this method
363 * <em>joins</em> the given path to this path and returns a resulting path
364 * that {@link #endsWith ends} with the given path. Where the given path has
365 * a root component then resolution is highly implementation dependent and
366 * therefore unspecified.
367 *
368 * @param other
369 * the path to resolve against this path
370 *
371 * @return the resulting path
372 *
373 * @see #relativize
374 */
375 Path resolve(Path other);
376
377 /**
378 * Converts a given path string to a {@code Path} and resolves it against
379 * this {@code Path} in exactly the manner specified by the {@link
380 * #resolve(Path) resolve} method. For example, suppose that the name
381 * separator is "{@code /}" and a path represents "{@code foo/bar}", then
382 * invoking this method with the path string "{@code gus}" will result in
383 * the {@code Path} "{@code foo/bar/gus}".
384 *
385 * @implSpec
386 * The default implementation is equivalent for this path to:
387 * <pre>{@code
388 * resolve(getFileSystem().getPath(other));
389 * }</pre>
390 *
391 * @param other
392 * the path string to resolve against this path
393 *
394 * @return the resulting path
395 *
396 * @throws InvalidPathException
397 * if the path string cannot be converted to a Path.
398 *
399 * @see FileSystem#getPath
400 */
401 default Path resolve(String other) {
402 return resolve(getFileSystem().getPath(other));
403 }
404
405 /**
406 * Resolves the given path against this path's {@link #getParent parent}
407 * path. This is useful where a file name needs to be <i>replaced</i> with
408 * another file name. For example, suppose that the name separator is
409 * "{@code /}" and a path represents "{@code dir1/dir2/foo}", then invoking
410 * this method with the {@code Path} "{@code bar}" will result in the {@code
411 * Path} "{@code dir1/dir2/bar}". If this path does not have a parent path,
412 * or {@code other} is {@link #isAbsolute() absolute}, then this method
413 * returns {@code other}. If {@code other} is an empty path then this method
414 * returns this path's parent, or where this path doesn't have a parent, the
415 * empty path.
416 *
417 * @implSpec
418 * The default implementation is equivalent for this path to:
419 * <pre>{@code
420 * (getParent() == null) ? other : getParent().resolve(other);
421 * }</pre>
422 * unless {@code other == null}, in which case a
423 * {@code NullPointerException} is thrown.
424 *
425 * @param other
426 * the path to resolve against this path's parent
427 *
428 * @return the resulting path
429 *
430 * @see #resolve(Path)
431 */
432 default Path resolveSibling(Path other) {
433 if (other == null)
434 throw new NullPointerException();
435 Path parent = getParent();
436 return (parent == null) ? other : parent.resolve(other);
437 }
438
439 /**
440 * Converts a given path string to a {@code Path} and resolves it against
441 * this path's {@link #getParent parent} path in exactly the manner
442 * specified by the {@link #resolveSibling(Path) resolveSibling} method.
443 *
444 * @implSpec
445 * The default implementation is equivalent for this path to:
446 * <pre>{@code
447 * resolveSibling(getFileSystem().getPath(other));
448 * }</pre>
449 *
450 * @param other
451 * the path string to resolve against this path's parent
452 *
453 * @return the resulting path
454 *
455 * @throws InvalidPathException
456 * if the path string cannot be converted to a Path.
457 *
458 * @see FileSystem#getPath
459 */
460 default Path resolveSibling(String other) {
461 return resolveSibling(getFileSystem().getPath(other));
462 }
463
464 /**
465 * Constructs a relative path between this path and a given path.
466 *
467 * <p> Relativization is the inverse of {@link #resolve(Path) resolution}.
468 * This method attempts to construct a {@link #isAbsolute relative} path
469 * that when {@link #resolve(Path) resolved} against this path, yields a
470 * path that locates the same file as the given path. For example, on UNIX,
471 * if this path is {@code "/a/b"} and the given path is {@code "/a/b/c/d"}
472 * then the resulting relative path would be {@code "c/d"}. Where this
473 * path and the given path do not have a {@link #getRoot root} component,
474 * then a relative path can be constructed. A relative path cannot be
475 * constructed if only one of the paths have a root component. Where both
476 * paths have a root component then it is implementation dependent if a
477 * relative path can be constructed. If this path and the given path are
478 * {@link #equals equal} then an <i>empty path</i> is returned.
479 *
480 * <p> For any two {@link #normalize normalized} paths <i>p</i> and
481 * <i>q</i>, where <i>q</i> does not have a root component,
482 * <blockquote>
483 * <i>p</i>{@code .relativize(}<i>p</i>
484 * {@code .resolve(}<i>q</i>{@code )).equals(}<i>q</i>{@code )}
485 * </blockquote>
486 *
487 * <p> When symbolic links are supported, then whether the resulting path,
488 * when resolved against this path, yields a path that can be used to locate
489 * the {@link Files#isSameFile same} file as {@code other} is implementation
490 * dependent. For example, if this path is {@code "/a/b"} and the given
491 * path is {@code "/a/x"} then the resulting relative path may be {@code
492 * "../x"}. If {@code "b"} is a symbolic link then is implementation
493 * dependent if {@code "a/b/../x"} would locate the same file as {@code "/a/x"}.
494 *
495 * @param other
496 * the path to relativize against this path
497 *
498 * @return the resulting relative path, or an empty path if both paths are
499 * equal
500 *
501 * @throws IllegalArgumentException
502 * if {@code other} is not a {@code Path} that can be relativized
503 * against this path
504 */
505 Path relativize(Path other);
506
507 /**
508 * Returns a URI to represent this path.
509 *
510 * <p> This method constructs an absolute {@link URI} with a {@link
511 * URI#getScheme() scheme} equal to the URI scheme that identifies the
512 * provider. The exact form of the scheme specific part is highly provider
513 * dependent.
514 *
515 * <p> In the case of the default provider, the URI is hierarchical with
516 * a {@link URI#getPath() path} component that is absolute. The query and
517 * fragment components are undefined. Whether the authority component is
518 * defined or not is implementation dependent. There is no guarantee that
519 * the {@code URI} may be used to construct a {@link java.io.File java.io.File}.
520 * In particular, if this path represents a Universal Naming Convention (UNC)
521 * path, then the UNC server name may be encoded in the authority component
522 * of the resulting URI. In the case of the default provider, and the file
523 * exists, and it can be determined that the file is a directory, then the
524 * resulting {@code URI} will end with a slash.
525 *
526 * <p> The default provider provides a similar <em>round-trip</em> guarantee
527 * to the {@link java.io.File} class. For a given {@code Path} <i>p</i> it
528 * is guaranteed that
529 * <blockquote>
530 * {@link Paths#get(URI) Paths.get}{@code (}<i>p</i>{@code .toUri()).equals(}<i>p</i>
531 * {@code .}{@link #toAbsolutePath() toAbsolutePath}{@code ())}
532 * </blockquote>
533 * so long as the original {@code Path}, the {@code URI}, and the new {@code
534 * Path} are all created in (possibly different invocations of) the same
535 * Java virtual machine. Whether other providers make any guarantees is
536 * provider specific and therefore unspecified.
537 *
538 * <p> When a file system is constructed to access the contents of a file
539 * as a file system then it is highly implementation specific if the returned
540 * URI represents the given path in the file system or it represents a
541 * <em>compound</em> URI that encodes the URI of the enclosing file system.
542 * A format for compound URIs is not defined in this release; such a scheme
543 * may be added in a future release.
544 *
545 * @return the URI representing this path
546 *
547 * @throws java.io.IOError
548 * if an I/O error occurs obtaining the absolute path, or where a
549 * file system is constructed to access the contents of a file as
550 * a file system, and the URI of the enclosing file system cannot be
551 * obtained
552 *
553 * @throws SecurityException
554 * In the case of the default provider, and a security manager
555 * is installed, the {@link #toAbsolutePath toAbsolutePath} method
556 * throws a security exception.
557 */
558 URI toUri();
559
560 /**
561 * Returns a {@code Path} object representing the absolute path of this
562 * path.
563 *
564 * <p> If this path is already {@link Path#isAbsolute absolute} then this
565 * method simply returns this path. Otherwise, this method resolves the path
566 * in an implementation dependent manner, typically by resolving the path
567 * against a file system default directory. Depending on the implementation,
568 * this method may throw an I/O error if the file system is not accessible.
569 *
570 * @return a {@code Path} object representing the absolute path
571 *
572 * @throws java.io.IOError
573 * if an I/O error occurs
574 * @throws SecurityException
575 * In the case of the default provider, a security manager
576 * is installed, and this path is not absolute, then the security
577 * manager's {@link SecurityManager#checkPropertyAccess(String)
578 * checkPropertyAccess} method is invoked to check access to the
579 * system property {@code user.dir}
580 */
581 Path toAbsolutePath();
582
583 /**
584 * Returns the <em>real</em> path of an existing file.
585 *
586 * <p> The precise definition of this method is implementation dependent but
587 * in general it derives from this path, an {@link #isAbsolute absolute}
588 * path that locates the {@link Files#isSameFile same} file as this path, but
589 * with name elements that represent the actual name of the directories
590 * and the file. For example, where filename comparisons on a file system
591 * are case insensitive then the name elements represent the names in their
592 * actual case. Additionally, the resulting path has redundant name
593 * elements removed.
594 *
595 * <p> If this path is relative then its absolute path is first obtained,
596 * as if by invoking the {@link #toAbsolutePath toAbsolutePath} method.
597 *
598 * <p> The {@code options} array may be used to indicate how symbolic links
599 * are handled. By default, symbolic links are resolved to their final
600 * target. If the option {@link LinkOption#NOFOLLOW_LINKS NOFOLLOW_LINKS} is
601 * present then this method does not resolve symbolic links.
602 *
603 * Some implementations allow special names such as "{@code ..}" to refer to
604 * the parent directory. When deriving the <em>real path</em>, and a
605 * "{@code ..}" (or equivalent) is preceded by a non-"{@code ..}" name then
606 * an implementation will typically cause both names to be removed. When
607 * not resolving symbolic links and the preceding name is a symbolic link
608 * then the names are only removed if it guaranteed that the resulting path
609 * will locate the same file as this path.
610 *
611 * @param options
612 * options indicating how symbolic links are handled
613 *
614 * @return an absolute path represent the <em>real</em> path of the file
615 * located by this object
616 *
617 * @throws IOException
618 * if the file does not exist or an I/O error occurs
619 * @throws SecurityException
620 * In the case of the default provider, and a security manager
621 * is installed, its {@link SecurityManager#checkRead(String) checkRead}
622 * method is invoked to check read access to the file, and where
623 * this path is not absolute, its {@link SecurityManager#checkPropertyAccess(String)
624 * checkPropertyAccess} method is invoked to check access to the
625 * system property {@code user.dir}
626 */
627 Path toRealPath(LinkOption... options) throws IOException;
628
629 /**
630 * Returns a {@link File} object representing this path. Where this {@code
631 * Path} is associated with the default provider, then this method is
632 * equivalent to returning a {@code File} object constructed with the
633 * {@code String} representation of this path.
634 *
635 * <p> If this path was created by invoking the {@code File} {@link
636 * File#toPath toPath} method then there is no guarantee that the {@code
637 * File} object returned by this method is {@link #equals equal} to the
638 * original {@code File}.
639 *
640 * @implSpec
641 * The default implementation is equivalent for this path to:
642 * <pre>{@code
643 * new File(toString());
644 * }</pre>
645 * if the {@code FileSystem} which created this {@code Path} is the default
646 * file system; otherwise an {@code UnsupportedOperationException} is
647 * thrown.
648 *
649 * @return a {@code File} object representing this path
650 *
651 * @throws UnsupportedOperationException
652 * if this {@code Path} is not associated with the default provider
653 */
654 default File toFile() {
655 if (getFileSystem() == FileSystems.getDefault()) {
656 return new File(toString());
657 } else {
658 throw new UnsupportedOperationException("Path not associated with "
659 + "default file system.");
660 }
661 }
662
663 // -- watchable --
664
665 /**
666 * Registers the file located by this path with a watch service.
667 *
668 * <p> In this release, this path locates a directory that exists. The
669 * directory is registered with the watch service so that entries in the
670 * directory can be watched. The {@code events} parameter is the events to
671 * register and may contain the following events:
672 * <ul>
673 * <li>{@link StandardWatchEventKinds#ENTRY_CREATE ENTRY_CREATE} -
674 * entry created or moved into the directory</li>
675 * <li>{@link StandardWatchEventKinds#ENTRY_DELETE ENTRY_DELETE} -
676 * entry deleted or moved out of the directory</li>
677 * <li>{@link StandardWatchEventKinds#ENTRY_MODIFY ENTRY_MODIFY} -
678 * entry in directory was modified</li>
679 * </ul>
680 *
681 * <p> The {@link WatchEvent#context context} for these events is the
682 * relative path between the directory located by this path, and the path
683 * that locates the directory entry that is created, deleted, or modified.
684 *
685 * <p> The set of events may include additional implementation specific
686 * event that are not defined by the enum {@link StandardWatchEventKinds}
687 *
688 * <p> The {@code modifiers} parameter specifies <em>modifiers</em> that
689 * qualify how the directory is registered. This release does not define any
690 * <em>standard</em> modifiers. It may contain implementation specific
691 * modifiers.
692 *
693 * <p> Where a file is registered with a watch service by means of a symbolic
694 * link then it is implementation specific if the watch continues to depend
695 * on the existence of the symbolic link after it is registered.
696 *
697 * @param watcher
698 * the watch service to which this object is to be registered
699 * @param events
700 * the events for which this object should be registered
701 * @param modifiers
702 * the modifiers, if any, that modify how the object is registered
703 *
704 * @return a key representing the registration of this object with the
705 * given watch service
706 *
707 * @throws UnsupportedOperationException
708 * if unsupported events or modifiers are specified
709 * @throws IllegalArgumentException
710 * if an invalid combination of events or modifiers is specified
711 * @throws ClosedWatchServiceException
712 * if the watch service is closed
713 * @throws NotDirectoryException
714 * if the file is registered to watch the entries in a directory
715 * and the file is not a directory <i>(optional specific exception)</i>
716 * @throws IOException
717 * if an I/O error occurs
718 * @throws SecurityException
719 * In the case of the default provider, and a security manager is
720 * installed, the {@link SecurityManager#checkRead(String) checkRead}
721 * method is invoked to check read access to the file.
722 */
723 @Override
724 WatchKey register(WatchService watcher,
725 WatchEvent.Kind<?>[] events,
726 WatchEvent.Modifier... modifiers)
727 throws IOException;
728
729 /**
730 * Registers the file located by this path with a watch service.
731 *
732 * <p> An invocation of this method behaves in exactly the same way as the
733 * invocation
734 * <pre>
735 * watchable.{@link #register(WatchService,WatchEvent.Kind[],WatchEvent.Modifier[]) register}(watcher, events, new WatchEvent.Modifier[0]);
736 * </pre>
737 *
738 * <p> <b>Usage Example:</b>
739 * Suppose we wish to register a directory for entry create, delete, and modify
740 * events:
741 * <pre>
742 * Path dir = ...
743 * WatchService watcher = ...
744 *
745 * WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
746 * </pre>
747 *
748 * @implSpec
749 * The default implementation is equivalent for this path to:
750 * <pre>{@code
751 * register(watcher, events, new WatchEvent.Modifier[0]);
752 * }</pre>
753 *
754 * @param watcher
755 * The watch service to which this object is to be registered
756 * @param events
757 * The events for which this object should be registered
758 *
759 * @return A key representing the registration of this object with the
760 * given watch service
761 *
762 * @throws UnsupportedOperationException
763 * If unsupported events are specified
764 * @throws IllegalArgumentException
765 * If an invalid combination of events is specified
766 * @throws ClosedWatchServiceException
767 * If the watch service is closed
768 * @throws NotDirectoryException
769 * If the file is registered to watch the entries in a directory
770 * and the file is not a directory <i>(optional specific exception)</i>
771 * @throws IOException
772 * If an I/O error occurs
773 * @throws SecurityException
774 * In the case of the default provider, and a security manager is
775 * installed, the {@link SecurityManager#checkRead(String) checkRead}
776 * method is invoked to check read access to the file.
777 */
778 @Override
779 default WatchKey register(WatchService watcher,
780 WatchEvent.Kind<?>... events) throws IOException {
781 return register(watcher, events, new WatchEvent.Modifier[0]);
782 }
783
784 // -- Iterable --
785
786 /**
787 * Returns an iterator over the name elements of this path.
788 *
789 * <p> The first element returned by the iterator represents the name
790 * element that is closest to the root in the directory hierarchy, the
791 * second element is the next closest, and so on. The last element returned
792 * is the name of the file or directory denoted by this path. The {@link
793 * #getRoot root} component, if present, is not returned by the iterator.
794 *
795 * @implSpec
796 * The default implementation returns an {@code Iterator<Path>} which, for
797 * this path, traverses the {@code Path}s returned by
798 * {@code getName(index)}, where {@code index} ranges from zero to
799 * {@code getNameCount() - 1}, inclusive.
800 *
801 * @return an iterator over the name elements of this path.
802 */
803 @Override
804 default Iterator<Path> iterator() {
805 return new Iterator<>() {
806 private int i = 0;
807
808 @Override
809 public boolean hasNext() {
810 return (i < getNameCount());
811 }
812
813 @Override
814 public Path next() {
815 if (i < getNameCount()) {
816 Path result = getName(i);
817 i++;
818 return result;
819 } else {
820 throw new NoSuchElementException();
821 }
822 }
823 };
824 }
825
826 // -- compareTo/equals/hashCode --
827
828 /**
829 * Compares two abstract paths lexicographically. The ordering defined by
830 * this method is provider specific, and in the case of the default
831 * provider, platform specific. This method does not access the file system
832 * and neither file is required to exist.
833 *
834 * <p> This method may not be used to compare paths that are associated
835 * with different file system providers.
836 *
837 * @param other the path compared to this path.
838 *
839 * @return zero if the argument is {@link #equals equal} to this path, a
840 * value less than zero if this path is lexicographically less than
841 * the argument, or a value greater than zero if this path is
842 * lexicographically greater than the argument
843 *
844 * @throws ClassCastException
845 * if the paths are associated with different providers
846 */
847 @Override
848 int compareTo(Path other);
849
850 /**
851 * Tests this path for equality with the given object.
852 *
853 * <p> If the given object is not a Path, or is a Path associated with a
854 * different {@code FileSystem}, then this method returns {@code false}.
855 *
856 * <p> Whether or not two path are equal depends on the file system
857 * implementation. In some cases the paths are compared without regard
858 * to case, and others are case sensitive. This method does not access the
859 * file system and the file is not required to exist. Where required, the
860 * {@link Files#isSameFile isSameFile} method may be used to check if two
861 * paths locate the same file.
862 *
863 * <p> This method satisfies the general contract of the {@link
864 * java.lang.Object#equals(Object) Object.equals} method. </p>
865 *
866 * @param other
867 * the object to which this object is to be compared
868 *
869 * @return {@code true} if, and only if, the given object is a {@code Path}
870 * that is identical to this {@code Path}
871 */
872 boolean equals(Object other);
873
874 /**
875 * Computes a hash code for this path.
876 *
877 * <p> The hash code is based upon the components of the path, and
878 * satisfies the general contract of the {@link Object#hashCode
879 * Object.hashCode} method.
880 *
881 * @return the hash-code value for this path
882 */
883 int hashCode();
884
885 /**
886 * Returns the string representation of this path.
887 *
888 * <p> If this path was created by converting a path string using the
889 * {@link FileSystem#getPath getPath} method then the path string returned
890 * by this method may differ from the original String used to create the path.
891 *
892 * <p> The returned path string uses the default name {@link
893 * FileSystem#getSeparator separator} to separate names in the path.
894 *
895 * @return the string representation of this path
896 */
897 String toString();
898 }