public class FilenameUtils extends Object
When dealing with file names, you can hit problems when moving from a Windows based development machine to a Unix based production machine. This class aims to help avoid those problems.
NOTE: You may be able to avoid using this class entirely simply by
using JDK File objects and the two argument constructor
File(File,String).
Most methods in this class are designed to work the same on both Unix and Windows. Those that don't include 'System', 'Unix', or 'Windows' in their name.
Most methods recognize both separators (forward and backslashes), and both sets of prefixes. See the Javadoc of each method for details.
This class defines six components within a path (sometimes called a file name or a full file name). Given an absolute Windows path such as C:\dev\project\file.txt they are:
Given an absolute Unix path such as /dev/project/file.txt they are:
Given a relative Windows path such as dev\project\file.txt they are:
Given an absolute Unix path such as /dev/project/file.txt they are:
This class works best if directory names end with a separator. If you omit the last separator, it is impossible to determine if the last component corresponds to a file or a directory. This class treats final components that do not end with a separator as files, not directories.
This class only supports Unix and Windows style names. Prefixes are matched as follows:
Windows: a\b\c.txt --> "" --> relative \a\b\c.txt --> "\" --> current drive absolute C:a\b\c.txt --> "C:" --> drive relative C:\a\b\c.txt --> "C:\" --> absolute \\server\a\b\c.txt --> "\\server\" --> UNC Unix: a/b/c.txt --> "" --> relative /a/b/c.txt --> "/" --> absolute ~/a/b/c.txt --> "~/" --> current user ~ --> "~/" --> current user (slash added) ~user/a/b/c.txt --> "~user/" --> named user ~user --> "~user/" --> named user (slash added)
Both prefix styles are matched, irrespective of the machine that you are currently running on.
| Modifier and Type | Field and Description |
|---|---|
static char |
EXTENSION_SEPARATOR
The extension separator character.
|
static String |
EXTENSION_SEPARATOR_STR
The extension separator String.
|
| Modifier and Type | Method and Description |
|---|---|
static String |
concat(String basePath,
String fullFileNameToAdd)
Concatenates a fileName to a base path using normal command line style rules.
|
static boolean |
directoryContains(String canonicalParent,
String canonicalChild)
Determines whether the
parent directory contains the child (a file or directory). |
static boolean |
equals(String fileName1,
String fileName2)
Checks whether two file names are exactly equal.
|
static boolean |
equals(String fileName1,
String fileName2,
boolean normalize,
IOCase ioCase)
Checks whether two file names are equal, optionally normalizing and providing
control over the case-sensitivity.
|
static boolean |
equalsNormalized(String fileName1,
String fileName2)
Checks whether two file names are equal after both have been normalized.
|
static boolean |
equalsNormalizedOnSystem(String fileName1,
String fileName2)
Checks whether two file names are equal using the case rules of the system
after both have been normalized.
|
static boolean |
equalsOnSystem(String fileName1,
String fileName2)
Checks whether two file names are equal using the case rules of the system.
|
(package private) static char |
flipSeparator(char ch)
Flips the Windows name separator to Linux and vice-versa.
|
static String |
getBaseName(String fileName)
Gets the base name, minus the full path and extension, from a full file name.
|
static String |
getExtension(String fileName)
Gets the extension of a file name.
|
static String |
getFullPath(String fileName)
Gets the full path (prefix + path) from a full file name.
|
static String |
getFullPathNoEndSeparator(String fileName)
Gets the full path (prefix + path) from a full file name,
excluding the final directory separator.
|
static String |
getName(String fileName)
Gets the name minus the path from a full file name.
|
static String |
getPath(String fileName)
Gets the path from a full file name, which excludes the prefix and the name.
|
static String |
getPathNoEndSeparator(String fileName)
Gets the path (which excludes the prefix) from a full file name, and
also excluding the final directory separator.
|
static String |
getPrefix(String fileName)
Gets the prefix such as
C:/ or ~/ from a full file name, |
static int |
getPrefixLength(String fileName)
Returns the length of the file name prefix, such as
C:/ or ~/. |
static int |
indexOfExtension(String fileName)
Returns the index of the last extension separator character, which is a period.
|
static int |
indexOfLastSeparator(String fileName)
Returns the index of the last directory separator character.
|
static boolean |
isExtension(String fileName,
Collection<String> extensions)
Checks whether the extension of the file name is one of those specified.
|
static boolean |
isExtension(String fileName,
String... extensions)
Checks whether the extension of the file name is one of those specified.
|
static boolean |
isExtension(String fileName,
String extension)
Checks whether the extension of the file name is that specified.
|
(package private) static boolean |
isSystemWindows()
Determines if Windows file system is in use.
|
static String |
normalize(String fileName)
Normalizes a path, removing double and single period path steps.
|
static String |
normalize(String fileName,
boolean unixSeparator)
Normalizes a path, removing double and single period path steps.
|
static String |
normalizeNoEndSeparator(String fileName)
Normalizes a path, removing double and single period path steps,
and removing any final directory separator.
|
static String |
normalizeNoEndSeparator(String fileName,
boolean unixSeparator)
Normalizes a path, removing double and single period path steps,
and removing any final directory separator.
|
static String |
removeExtension(String fileName)
Removes the extension from a fileName.
|
static String |
separatorsToSystem(String path)
Converts all separators to the system separator.
|
static String |
separatorsToUnix(String path)
Converts all separators to the Unix separator of forward slash.
|
static String |
separatorsToWindows(String path)
Converts all separators to the Windows separator of backslash.
|
(package private) static String[] |
splitOnTokens(String text)
Splits a string into a number of tokens.
|
static boolean |
wildcardMatch(String fileName,
String wildcardMatcher)
Checks a fileName to see if it matches the specified wildcard matcher,
always testing case-sensitive.
|
static boolean |
wildcardMatch(String fileName,
String wildcardMatcher,
IOCase ioCase)
Checks a fileName to see if it matches the specified wildcard matcher
allowing control over case-sensitivity.
|
static boolean |
wildcardMatchOnSystem(String fileName,
String wildcardMatcher)
Checks a fileName to see if it matches the specified wildcard matcher
using the case rules of the system.
|
public static final char EXTENSION_SEPARATOR
public static final String EXTENSION_SEPARATOR_STR
public static String concat(String basePath, String fullFileNameToAdd)
The effect is equivalent to resultant directory after changing directory to the first argument, followed by changing directory to the second argument.
The first argument is the base path, the second is the path to concatenate.
The returned path is always normalized via normalize(String),
thus .. is handled.
If pathToAdd is absolute (has an absolute prefix), then
it will be normalized and returned.
Otherwise, the paths will be joined, normalized and returned.
The output will be the same on both Unix and Windows except for the separator character.
/foo/ + bar --> /foo/bar /foo + bar --> /foo/bar /foo + /bar --> /bar /foo + C:/bar --> C:/bar /foo + C:bar --> C:bar [1] /foo/a/ + ../bar --> /foo/bar /foo/ + ../../bar --> null /foo/ + /bar --> /bar /foo/.. + /bar --> /bar /foo + bar/c.txt --> /foo/bar/c.txt /foo/c.txt + bar --> /foo/c.txt/bar [2]
[1] Note that the Windows relative drive prefix is unreliable when used with this method.
[2] Note that the first parameter must be a path. If it ends with a name, then
the name will be built into the concatenated path. If this might be a problem,
use getFullPath(String) on the base path argument.
basePath - the base path to attach to, always treated as a pathfullFileNameToAdd - the file name (or path) to attach to the baseIllegalArgumentException - if the result path contains the null character (U+0000)public static boolean directoryContains(String canonicalParent, String canonicalChild)
parent directory contains the child (a file or directory).
This does not read from the file system, and there is no guarantee or expectation that
these paths actually exist.
The files names are expected to be normalized.
Edge cases:directory must not be null: if null, throw IllegalArgumentExceptioncanonicalParent - the path string to consider as the parent.canonicalChild - the path string to consider as the child.FileUtils.directoryContains(File, File)public static boolean equals(String fileName1, String fileName2)
No processing is performed on the file names other than comparison. This is merely a null-safe case-sensitive string equality.
fileName1 - the first file name, may be nullfileName2 - the second file name, may be nullIOCase.SENSITIVEpublic static boolean equals(String fileName1, String fileName2, boolean normalize, IOCase ioCase)
fileName1 - the first file name, may be nullfileName2 - the second file name, may be nullnormalize - whether to normalize the file namesioCase - what case sensitivity rule to use, null means case-sensitivepublic static boolean equalsNormalized(String fileName1, String fileName2)
Both file names are first passed to normalize(String).
The check is then performed in a case-sensitive manner.
fileName1 - the first file name, may be nullfileName2 - the second file name, may be nullIOCase.SENSITIVEpublic static boolean equalsNormalizedOnSystem(String fileName1, String fileName2)
Both file names are first passed to normalize(String).
The check is then performed case-sensitively on Unix and
case-insensitively on Windows.
fileName1 - the first file name, may be nullfileName2 - the second file name, may be nullIOCase.SYSTEMpublic static boolean equalsOnSystem(String fileName1, String fileName2)
No processing is performed on the file names other than comparison. The check is case-sensitive on Unix and case-insensitive on Windows.
fileName1 - the first file name, may be nullfileName2 - the second file name, may be nullIOCase.SYSTEMstatic char flipSeparator(char ch)
ch - The Windows or Linux name separator.public static String getBaseName(String fileName)
This method will handle a path in either Unix or Windows format. The text after the last forward or backslash and before the last period is returned.
a/b/c.txt --> c a\b\c.txt --> c a/b/c.foo.txt --> c.foo a.txt --> a a/b/c --> c a/b/c/ --> ""
The output will be the same irrespective of the machine that the code is running on.
fileName - the file name, null returns nullIllegalArgumentException - if the file name contains the null character (U+0000)public static String getExtension(String fileName) throws IllegalArgumentException
This method returns the textual part of the file name after the last period. There must be no directory separator after the period.
foo.txt --> "txt" a/b/c.jpg --> "jpg" a/b.txt/c --> "" a/b/c --> ""
The output will be the same irrespective of the machine that the code is running on, with the
exception of a possible IllegalArgumentException on Windows (see below).
Note: This method used to have a hidden problem for names like "foo.exe:bar.txt".
In this case, the name wouldn't be the name of a file, but the identifier of an
alternate data stream (bar.txt) on the file foo.exe. The method used to return
".txt" here, which would be misleading. Commons IO 2.7 and later throw
an IllegalArgumentException for names like this.
fileName - the file name to retrieve the extension of.null
if the file name is null.IllegalArgumentException - Windows only: the file name parameter is, in fact,
the identifier of an Alternate Data Stream, for example "foo.exe:bar.txt".public static String getFullPath(String fileName)
This method will handle a file in either Unix or Windows format. The method is entirely text based, and returns the text before and including the last forward or backslash.
C:\a\b\c.txt --> C:\a\b\ ~/a/b/c.txt --> ~/a/b/ a.txt --> "" a/b/c --> a/b/ a/b/c/ --> a/b/c/ C: --> C: C:\ --> C:\ ~ --> ~/ ~/ --> ~/ ~user --> ~user/ ~user/ --> ~user/
The output will be the same irrespective of the machine that the code is running on.
fileName - the file name, null returns nullIllegalArgumentException - if the result path contains the null character (U+0000)public static String getFullPathNoEndSeparator(String fileName)
This method will handle a file in either Unix or Windows format. The method is entirely text based, and returns the text before the last forward or backslash.
C:\a\b\c.txt --> C:\a\b ~/a/b/c.txt --> ~/a/b a.txt --> "" a/b/c --> a/b a/b/c/ --> a/b/c C: --> C: C:\ --> C:\ ~ --> ~ ~/ --> ~ ~user --> ~user ~user/ --> ~user
The output will be the same irrespective of the machine that the code is running on.
fileName - the file name, null returns nullIllegalArgumentException - if the result path contains the null character (U+0000)public static String getName(String fileName)
This method will handle a file in either Unix or Windows format. The text after the last forward or backslash is returned.
a/b/c.txt --> c.txt a\b\c.txt --> c.txt a.txt --> a.txt a/b/c --> c a/b/c/ --> ""
The output will be the same irrespective of the machine that the code is running on.
fileName - the file name, null returns nullIllegalArgumentException - if the file name contains the null character (U+0000)public static String getPath(String fileName)
This method will handle a file in either Unix or Windows format. The method is entirely text based, and returns the text before and including the last forward or backslash.
C:\a\b\c.txt --> a\b\ ~/a/b/c.txt --> a/b/ a.txt --> "" a/b/c --> a/b/ a/b/c/ --> a/b/c/
The output will be the same irrespective of the machine that the code is running on.
This method drops the prefix from the result.
See getFullPath(String) for the method that retains the prefix.
fileName - the file name, null returns nullIllegalArgumentException - if the result path contains the null character (U+0000)public static String getPathNoEndSeparator(String fileName)
This method will handle a file in either Unix or Windows format. The method is entirely text based, and returns the text before the last forward or backslash.
C:\a\b\c.txt --> a\b ~/a/b/c.txt --> a/b a.txt --> "" a/b/c --> a/b a/b/c/ --> a/b/c
The output will be the same irrespective of the machine that the code is running on.
This method drops the prefix from the result.
See getFullPathNoEndSeparator(String) for the method that retains the prefix.
fileName - the file name, null returns nullIllegalArgumentException - if the result path contains the null character (U+0000)public static String getPrefix(String fileName)
C:/ or ~/ from a full file name,
This method will handle a file in either Unix or Windows format. The prefix includes the first slash in the full file name where applicable.
Windows: a\b\c.txt --> "" --> relative \a\b\c.txt --> "\" --> current drive absolute C:a\b\c.txt --> "C:" --> drive relative C:\a\b\c.txt --> "C:\" --> absolute \\server\a\b\c.txt --> "\\server\" --> UNC Unix: a/b/c.txt --> "" --> relative /a/b/c.txt --> "/" --> absolute ~/a/b/c.txt --> "~/" --> current user ~ --> "~/" --> current user (slash added) ~user/a/b/c.txt --> "~user/" --> named user ~user --> "~user/" --> named user (slash added)
The output will be the same irrespective of the machine that the code is running on. ie. both Unix and Windows prefixes are matched regardless.
fileName - the file name, null returns nullIllegalArgumentException - if the result contains the null character (U+0000)public static int getPrefixLength(String fileName)
C:/ or ~/.
This method will handle a file in either Unix or Windows format.
The prefix length includes the first slash in the full file name if applicable. Thus, it is possible that the length returned is greater than the length of the input string.
Windows: a\b\c.txt --> 0 --> relative \a\b\c.txt --> 1 --> current drive absolute C:a\b\c.txt --> 2 --> drive relative C:\a\b\c.txt --> 3 --> absolute \\server\a\b\c.txt --> 9 --> UNC \\\a\b\c.txt --> -1 --> error Unix: a/b/c.txt --> 0 --> relative /a/b/c.txt --> 1 --> absolute ~/a/b/c.txt --> 2 --> current user ~ --> 2 --> current user (slash added) ~user/a/b/c.txt --> 6 --> named user ~user --> 6 --> named user (slash added) //server/a/b/c.txt --> 9 ///a/b/c.txt --> -1 --> error C: --> 0 --> valid file name as only null character and / are reserved characters
The output will be the same irrespective of the machine that the code is running on. ie. both Unix and Windows prefixes are matched regardless.
Note that a leading // (or \\) is used to indicate a UNC name on Windows. These must be followed by a server name, so double-slashes are not collapsed to a single slash at the start of the file name.
fileName - the file name to find the prefix in, null returns -1public static int indexOfExtension(String fileName) throws IllegalArgumentException
This method also checks that there is no directory separator after the last period. To do this it uses
indexOfLastSeparator(String) which will handle a file in either Unix or Windows format.
The output will be the same irrespective of the machine that the code is running on, with the
exception of a possible IllegalArgumentException on Windows (see below).
IllegalArgumentException for names like this.fileName - the file name to find the last extension separator in, null returns -1IllegalArgumentException - Windows only: the file name parameter is, in fact,
the identifier of an Alternate Data Stream, for example "foo.exe:bar.txt".public static int indexOfLastSeparator(String fileName)
This method will handle a file in either Unix or Windows format. The position of the last forward or backslash is returned.
The output will be the same irrespective of the machine that the code is running on.
fileName - the file name to find the last path separator in, null returns -1public static boolean isExtension(String fileName, Collection<String> extensions)
This method obtains the extension as the textual part of the file name after the last period. There must be no directory separator after the period. The extension check is case-sensitive on all platforms.
fileName - the file name, null returns falseextensions - the extensions to check for, null checks for no extensionIllegalArgumentException - if the file name contains the null character (U+0000)public static boolean isExtension(String fileName, String... extensions)
This method obtains the extension as the textual part of the file name after the last period. There must be no directory separator after the period. The extension check is case-sensitive on all platforms.
fileName - the file name, null returns falseextensions - the extensions to check for, null checks for no extensionIllegalArgumentException - if the file name contains the null character (U+0000)public static boolean isExtension(String fileName, String extension)
This method obtains the extension as the textual part of the file name after the last period. There must be no directory separator after the period. The extension check is case-sensitive on all platforms.
fileName - the file name, null returns falseextension - the extension to check for, null or empty checks for no extensionIllegalArgumentException - if the file name contains the null character (U+0000)static boolean isSystemWindows()
public static String normalize(String fileName)
This method normalizes a path to a standard format. The input may contain separators in either Unix or Windows format. The output will contain separators in the format of the system.
A trailing slash will be retained.
A double slash will be merged to a single slash (but UNC names are handled).
A single period path segment will be removed.
A double period will cause that path segment and the one before to be removed.
If the double period has no parent path segment, null is returned.
The output will be the same on both Unix and Windows except for the separator character.
/foo// --> /foo/ /foo/./ --> /foo/ /foo/../bar --> /bar /foo/../bar/ --> /bar/ /foo/../bar/../baz --> /baz //foo//./bar --> //foo/bar /../ --> null ../foo --> null foo/bar/.. --> foo/ foo/../../bar --> null foo/../bar --> bar //server/foo/../bar --> //server/bar //server/../bar --> null C:\foo\..\bar --> C:\bar C:\..\bar --> null ~/foo/../bar/ --> ~/bar/ ~/../bar --> null(Note the file separator will be correct for Windows/Unix.)
fileName - the file name to normalize, null returns nullIllegalArgumentException - if the file name contains the null character (U+0000)public static String normalize(String fileName, boolean unixSeparator)
This method normalizes a path to a standard format. The input may contain separators in either Unix or Windows format. The output will contain separators in the format specified.
A trailing slash will be retained.
A double slash will be merged to a single slash (but UNC names are handled).
A single period path segment will be removed.
A double period will cause that path segment and the one before to be removed.
If the double period has no parent path segment to work with, null
is returned.
The output will be the same on both Unix and Windows except for the separator character.
/foo// --> /foo/ /foo/./ --> /foo/ /foo/../bar --> /bar /foo/../bar/ --> /bar/ /foo/../bar/../baz --> /baz //foo//./bar --> /foo/bar /../ --> null ../foo --> null foo/bar/.. --> foo/ foo/../../bar --> null foo/../bar --> bar //server/foo/../bar --> //server/bar //server/../bar --> null C:\foo\..\bar --> C:\bar C:\..\bar --> null ~/foo/../bar/ --> ~/bar/ ~/../bar --> nullThe output will be the same on both Unix and Windows including the separator character.
fileName - the file name to normalize, null returns nullunixSeparator - true if a Unix separator should
be used or false if a Windows separator should be used.IllegalArgumentException - if the file name contains the null character (U+0000)public static String normalizeNoEndSeparator(String fileName)
This method normalizes a path to a standard format. The input may contain separators in either Unix or Windows format. The output will contain separators in the format of the system.
A trailing slash will be removed.
A double slash will be merged to a single slash (but UNC names are handled).
A single period path segment will be removed.
A double period will cause that path segment and the one before to be removed.
If the double period has no parent path segment to work with, null
is returned.
The output will be the same on both Unix and Windows except for the separator character.
/foo// --> /foo /foo/./ --> /foo /foo/../bar --> /bar /foo/../bar/ --> /bar /foo/../bar/../baz --> /baz //foo//./bar --> /foo/bar /../ --> null ../foo --> null foo/bar/.. --> foo foo/../../bar --> null foo/../bar --> bar //server/foo/../bar --> //server/bar //server/../bar --> null C:\foo\..\bar --> C:\bar C:\..\bar --> null ~/foo/../bar/ --> ~/bar ~/../bar --> null(Note the file separator returned will be correct for Windows/Unix)
fileName - the file name to normalize, null returns nullIllegalArgumentException - if the file name contains the null character (U+0000)public static String normalizeNoEndSeparator(String fileName, boolean unixSeparator)
This method normalizes a path to a standard format. The input may contain separators in either Unix or Windows format. The output will contain separators in the format specified.
A trailing slash will be removed.
A double slash will be merged to a single slash (but UNC names are handled).
A single period path segment will be removed.
A double period will cause that path segment and the one before to be removed.
If the double period has no parent path segment to work with, null
is returned.
The output will be the same on both Unix and Windows including the separator character.
/foo// --> /foo /foo/./ --> /foo /foo/../bar --> /bar /foo/../bar/ --> /bar /foo/../bar/../baz --> /baz //foo//./bar --> /foo/bar /../ --> null ../foo --> null foo/bar/.. --> foo foo/../../bar --> null foo/../bar --> bar //server/foo/../bar --> //server/bar //server/../bar --> null C:\foo\..\bar --> C:\bar C:\..\bar --> null ~/foo/../bar/ --> ~/bar ~/../bar --> null
fileName - the file name to normalize, null returns nullunixSeparator - true if a Unix separator should
be used or false if a Windows separator should be used.IllegalArgumentException - if the file name contains the null character (U+0000)public static String removeExtension(String fileName)
This method returns the textual part of the file name before the last period. There must be no directory separator after the period.
foo.txt --> foo .txt --> "" (empty string) a\b\c.jpg --> a\b\c /a/b/c.jpg --> /a/b/c a\b\c --> a\b\c a.b\c --> a.b\c
The output will be the same irrespective of the machine that the code is running on.
fileName - the file name, null returns nullIllegalArgumentException - if the file name contains the null character (U+0000)public static String separatorsToSystem(String path)
path - the path to be changed, null ignored.public static String separatorsToUnix(String path)
path - the path to be changed, null ignored.public static String separatorsToWindows(String path)
path - the path to be changed, null ignored.static String[] splitOnTokens(String text)
text - the text to splitpublic static boolean wildcardMatch(String fileName, String wildcardMatcher)
The wildcard matcher uses the characters '?' and '*' to represent a single or multiple (zero or more) wildcard characters. This is the same as often found on DOS/Unix command lines. The check is case-sensitive always.
wildcardMatch("c.txt", "*.txt") --> true
wildcardMatch("c.txt", "*.jpg") --> false
wildcardMatch("a/b/c.txt", "a/b/*") --> true
wildcardMatch("c.txt", "*.???") --> true
wildcardMatch("c.txt", "*.????") --> false
The sequence "*?" does not work properly at present in match strings.fileName - the file name to match onwildcardMatcher - the wildcard string to match againstIOCase.SENSITIVEpublic static boolean wildcardMatch(String fileName, String wildcardMatcher, IOCase ioCase)
The wildcard matcher uses the characters '?' and '*' to represent a single or multiple (zero or more) wildcard characters. The sequence "*?" does not work properly at present in match strings.
fileName - the file name to match onwildcardMatcher - the wildcard string to match againstioCase - what case sensitivity rule to use, null means case-sensitivepublic static boolean wildcardMatchOnSystem(String fileName, String wildcardMatcher)
The wildcard matcher uses the characters '?' and '*' to represent a single or multiple (zero or more) wildcard characters. This is the same as often found on DOS/Unix command lines. The check is case-sensitive on Unix and case-insensitive on Windows.
wildcardMatch("c.txt", "*.txt") --> true
wildcardMatch("c.txt", "*.jpg") --> false
wildcardMatch("a/b/c.txt", "a/b/*") --> true
wildcardMatch("c.txt", "*.???") --> true
wildcardMatch("c.txt", "*.????") --> false
The sequence "*?" does not work properly at present in match strings.fileName - the file name to match onwildcardMatcher - the wildcard string to match againstIOCase.SYSTEM