public final Class IoUtils

Size of preferred work buffer when reading / writing data to / from streams

The local O/S line separator

A Set of StandardOpenOption-s that indicate an intent to create/modify a file

Build a path from the list of path parts

Parameters

root:Path

the root path

fs:FileSystem

the filesystem

namesList:List<String>

the parts of the path to build

Returns:Path

the built path

Build a relative path on the filesystem fs from the path parts in the namesList

Parameters

fs:FileSystem

the filesystem for the path

namesList:List<String>

the names list

Returns:Path

the built path

Checks if a file exists - Note: according to the Java tutorial - Checking a File or Directory:

The methods in the Path class are syntactic, meaning that they operate
on the Path instance. But eventually you must access the file system
to verify that a particular Path exists, or does not exist. You can do
so with the exists(Path, LinkOption...) and the notExists(Path, LinkOption...)
methods. Note that !Files.exists(path) is not equivalent to Files.notExists(path).
When you are testing a file's existence, three results are possible:

- The file is verified to exist.
- The file is verified to not exist.
- The file's status is unknown.

This result can occur when the program does not have access to the file.
If both exists and notExists return false, the existence of the file cannot
be verified.

Parameters

path:Path

The Path to be tested

options:LinkOption[]

The LinkOptions to use

Returns:Boolean

Boolean#TRUE/Boolean#FALSE or null according to the file status as explained above

Checks that a file exists with or without following any symlinks.

Parameters

path:Path

the path to check

neverFollowSymlinks:boolean

whether to follow symlinks

Returns:Boolean

true if the file exists with the symlink semantics, false if it doesn't exist, null if symlinks were found, or it is unknown if whether the file exists

Chroot a path under the new root

Parameters

newRoot:Path

the new root

toSanitize:Path

the path to sanitize and chroot

Returns:Path

the chrooted path under the newRoot filesystem

Closes a bunch of resources suppressing any IOExceptions their Closeable#close() method may have thrown

Parameters

closeables:Closeable[]

The Closeables to close

Returns:IOException

The first IOException that occurred during closing of a resource - null if not exception. If more than one exception occurred, they are added as suppressed exceptions to the first one

Annotations

@SuppressWarnings:ThrowableResultOfMethodCallIgnored

See Also

Throwable#getSuppressed()

Closes the specified Closeable resource

Parameters

c:Closeable

The resource to close - ignored if null

Returns:IOException

The thrown IOException when close() was called - null if no exception was thrown (or no resource to close to begin with)

Annotations

@SuppressWarnings:ThrowableResultOfMethodCallIgnored

Closes a bunch of resources suppressing any IOExceptions their Closeable#close() method may have thrown

Parameters

closeables:Collection<? extends Closeable>

The Closeables to close

Returns:IOException

The first IOException that occurred during closing of a resource - null if not exception. If more than one exception occurred, they are added as suppressed exceptions to the first one

Annotations

@SuppressWarnings:ThrowableResultOfMethodCallIgnored

See Also

Throwable#getSuppressed()

Parameters

path:Path

The Path to check

options:LinkOption[]

The LinkOptions to use when checking if path is a directory

Returns:Path

The same input path if it is a directory

Exceptions

UnsupportedOperationException:

if input path not a directory

Parameters

options:LinkOption[]

The LinkOptions - OK if null/empty

Returns:boolean

true if the link options are null/empty or do not contain LinkOption#NOFOLLOW_LINKS, false otherwise (i.e., the array is not empty and contains the special value)

Returns:byte[]

The local platform line separator bytes as UTF-8

Note

each call returns a new instance in order to avoid inadvertent changes in shared objects

See Also

EOL

Get file owner.

Parameters

path:Path

The Path

options:LinkOption[]

The LinkOptions to use when querying the owner

Returns:String

Owner of the file or null if unsupported

Note

for Windows it strips any prepended domain or group name

Exceptions

IOException:

If failed to access the file system

See Also

Files#getOwner(Path, LinkOption...)

Extracts the first n parts of the path. For example
("/home/test/test12", 1) returns "/home",
("/home/test", 1) returns "/home/test"
etc.

Parameters

path:Path

the path to extract parts of

partsToExtract:int

the number of parts to extract

Returns:Path

the extracted path

If the "posix" view is supported, then it returns Files#getPosixFilePermissions(Path, LinkOption...), otherwise uses the getPermissionsFromFile(File) method

Parameters

path:Path

The Path

options:LinkOption[]

The LinkOptions to use when querying the permissions

Returns:Set<PosixFilePermission>

A Set of PosixFilePermission

Exceptions

IOException:

If failed to access the file system in order to retrieve the permissions

Parameters

f:File

The File to be checked

Returns:Set<PosixFilePermission>

A Set of PosixFilePermissions based on whether the file is readable/writable/executable. If so, then all the relevant permissions are set (i.e., owner, group and others)

Parameters

fileName:String

The file name to be evaluated - ignored if null/empty

Returns:boolean

true if the file ends in one of the WINDOWS_EXECUTABLE_EXTENSIONS

Read as many bytes as possible until EOF or achieved required length

Parameters

input:InputStream

where to read input from

buffer:byte[]

destination

Returns:int

actual length read; may be less than requested if EOF was reached

Exceptions

IOException:

if a read error occurs

Read as many bytes as possible until EOF or achieved required length

Parameters

input:InputStream

where to read input from

buffer:byte[]

destination

offset:int

initial offset into buffer

length:int

length to read - ignored if non-positive

Returns:int

actual length read; may be less than requested if EOF was reached

Exceptions

IOException:

if a read error occurs

Reads all lines until no more available

Parameters

url:URL

The URL to read from

Returns:List<String>

The List of lines in the same order as it was read

Exceptions

IOException:

If failed to read the lines

See Also

readAllLines(InputStream)

Reads all lines until no more available

Parameters

stream:InputStream

The InputStream - Note: assumed to contain UTF-8 encoded data

Returns:List<String>

The List of lines in the same order as it was read

Exceptions

IOException:

If failed to read the lines

See Also

readAllLines(Reader)

Reads all lines until no more available

Parameters

reader:BufferedReader

The BufferedReader to read all lines

Returns:List<String>

The List of lines in the same order as it was read

Exceptions

IOException:

If failed to read the lines

See Also

readAllLines(BufferedReader, int)

Reads all lines until no more available

Parameters

reader:BufferedReader

The BufferedReader to read all lines

lineCountHint:int

A hint as to the expected number of lines - non-positive means unknown - in which case some initial default value will be used to initialize the list used to accumulate the lines.

Returns:List<String>

The List of lines in the same order as it was read

Exceptions

IOException:

If failed to read the lines

Read the requested number of bytes or fail if there are not enough left.

Parameters

input:InputStream

where to read input from

buffer:byte[]

destination

Exceptions

IOException:

if there is a problem reading the file

EOFException:

if the number of bytes read was incorrect

Read the requested number of bytes or fail if there are not enough left.

Parameters

input:InputStream

where to read input from

buffer:byte[]

destination

offset:int

initial offset into buffer

length:int

length to read, must be ≥ 0

Exceptions

IOException:

if there is a problem reading the file

EOFException:

if the number of bytes read was incorrect

Remove any extra directory ups from the Path

Parameters

toSanitize:Path

the path to sanitize

Returns:Path

the sanitized path

If the "posix" view is supported, then it invokes Files#setPosixFilePermissions(Path, Set), otherwise uses the setPermissionsToFile(File, Collection) method

Parameters

path:Path

The Path

perms:Set<PosixFilePermission>

The Set of PosixFilePermissions

Exceptions

IOException:

If failed to access the file system

Parameters

f:File

The File

perms:Collection<PosixFilePermission>

A Collection of PosixFilePermissions to set on it

Note

the file is set to readable/writable/executable not only by the owner if any of relevant the owner/group/others permission is set

Parameters

perms:Collection<PosixFilePermission>

The current PosixFilePermissions - ignored if null/empty

excluded:Collection<PosixFilePermission>

The permissions not allowed to exist - ignored if null/empty

Returns:PosixFilePermission

The violating PosixFilePermission - null if no violating permission found