FileStore

public abstract class FileStore
extends Object

java.lang.Object
   ↳ java.nio.file.FileStore


Storage for files. A FileStore represents a storage pool, device, partition, volume, concrete file system or other implementation specific means of file storage. The FileStore for where a file is stored is obtained by invoking the getFileStore method, or all file stores can be enumerated by invoking the getFileStores method.

In addition to the methods defined by this class, a file store may support one or more FileStoreAttributeView classes that provide a read-only or updatable view of a set of file store attributes.

Summary

Protected constructors

FileStore()

Initializes a new instance of this class.

Public methods

abstract Object getAttribute(String attribute)

Reads the value of a file store attribute.

abstract <V extends FileStoreAttributeView> V getFileStoreAttributeView(Class<V> type)

Returns a FileStoreAttributeView of the given type.

abstract long getTotalSpace()

Returns the size, in bytes, of the file store.

abstract long getUnallocatedSpace()

Returns the number of unallocated bytes in the file store.

abstract long getUsableSpace()

Returns the number of bytes available to this Java virtual machine on the file store.

abstract boolean isReadOnly()

Tells whether this file store is read-only.

abstract String name()

Returns the name of this file store.

abstract boolean supportsFileAttributeView(String name)

Tells whether or not this file store supports the file attributes identified by the given file attribute view.

abstract boolean supportsFileAttributeView(Class<? extends FileAttributeView> type)

Tells whether or not this file store supports the file attributes identified by the given file attribute view.

abstract String type()

Returns the type of this file store.

Inherited methods

Protected constructors

FileStore

added in API level 26
FileStore ()

Initializes a new instance of this class.

Public methods

getAttribute

added in API level 26
Object getAttribute (String attribute)

Reads the value of a file store attribute.

The attribute parameter identifies the attribute to be read and takes the form:

view-name:attribute-name
where the character ':' stands for itself.

view-name is the name of a AttributeView that identifies a set of file attributes. attribute-name is the name of the attribute.

Usage Example: Suppose we want to know if ZFS compression is enabled (assuming the "zfs" view is supported):

    boolean compression = (Boolean)fs.getAttribute("zfs:compression");
 

Parameters
attribute String: the attribute to read

Returns
Object the attribute value; null may be a valid valid for some attributes

Throws
UnsupportedOperationException if the attribute view is not available or it does not support reading the attribute
IOException if an I/O error occurs

getFileStoreAttributeView

added in API level 26
V getFileStoreAttributeView (Class<V> type)

Returns a FileStoreAttributeView of the given type.

This method is intended to be used where the file store attribute view defines type-safe methods to read or update the file store attributes. The type parameter is the type of the attribute view required and the method returns an instance of that type if supported.

Parameters
type Class: the Class object corresponding to the attribute view

Returns
V a file store attribute view of the specified type or null if the attribute view is not available

getTotalSpace

added in API level 26
long getTotalSpace ()

Returns the size, in bytes, of the file store.

Returns
long the size of the file store, in bytes

Throws
IOException if an I/O error occurs

getUnallocatedSpace

added in API level 26
long getUnallocatedSpace ()

Returns the number of unallocated bytes in the file store.

The returned number of unallocated bytes is a hint, but not a guarantee, that it is possible to use most or any of these bytes. The number of unallocated bytes is most likely to be accurate immediately after the space attributes are obtained. It is likely to be made inaccurate by any external I/O operations including those made on the system outside of this virtual machine.

Returns
long the number of unallocated bytes

Throws
IOException if an I/O error occurs

getUsableSpace

added in API level 26
long getUsableSpace ()

Returns the number of bytes available to this Java virtual machine on the file store.

The returned number of available bytes is a hint, but not a guarantee, that it is possible to use most or any of these bytes. The number of usable bytes is most likely to be accurate immediately after the space attributes are obtained. It is likely to be made inaccurate by any external I/O operations including those made on the system outside of this Java virtual machine.

Returns
long the number of bytes available

Throws
IOException if an I/O error occurs

isReadOnly

added in API level 26
boolean isReadOnly ()

Tells whether this file store is read-only. A file store is read-only if it does not support write operations or other changes to files. Any attempt to create a file, open an existing file for writing etc. causes an IOException to be thrown.

Returns
boolean true if, and only if, this file store is read-only

name

added in API level 26
String name ()

Returns the name of this file store. The format of the name is highly implementation specific. It will typically be the name of the storage pool or volume.

The string returned by this method may differ from the string returned by the toString method.

Returns
String the name of this file store

supportsFileAttributeView

added in API level 26
boolean supportsFileAttributeView (String name)

Tells whether or not this file store supports the file attributes identified by the given file attribute view.

Invoking this method to test if the file store supports BasicFileAttributeView, identified by the name "basic" will always return true. In the case of the default provider, this method cannot guarantee to give the correct result when the file store is not a local storage device. The reasons for this are implementation specific and therefore unspecified.

Parameters
name String: the name of file attribute view

Returns
boolean true if, and only if, the file attribute view is supported

supportsFileAttributeView

added in API level 26
boolean supportsFileAttributeView (Class<? extends FileAttributeView> type)

Tells whether or not this file store supports the file attributes identified by the given file attribute view.

Invoking this method to test if the file store supports BasicFileAttributeView will always return true. In the case of the default provider, this method cannot guarantee to give the correct result when the file store is not a local storage device. The reasons for this are implementation specific and therefore unspecified.

Parameters
type Class: the file attribute view type

Returns
boolean true if, and only if, the file attribute view is supported

type

added in API level 26
String type ()

Returns the type of this file store. The format of the string returned by this method is highly implementation specific. It may indicate, for example, the format used or if the file store is local or remote.

Returns
String a string representing the type of this file store