Added in API level 26

Summary: Protected Ctors | Methods | Inherited Methods

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.
long	getBlockSize() Returns the number of bytes per block in this file store.
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

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Protected constructors

FileStore

Added in API level 26

protected FileStore ()

Initializes a new instance of this class.

Public methods

getAttribute

Added in API level 26

public abstract 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 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

getBlockSize

Added in API level 33

public long getBlockSize ()

Returns the number of bytes per block in this file store.

File storage is typically organized into discrete sequences of bytes called blocks. A block is the smallest storage unit of a file store. Every read and write operation is performed on a multiple of blocks.

Implementation Requirements:

• The implementation in this class throws an UnsupportedOperationException.

Returns
long	a positive value representing the block size of this file store, in bytes

Throws
IOException	if an I/O error occurs
UnsupportedOperationException	if the operation is not supported

getFileStoreAttributeView

Added in API level 26

public abstract 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

public abstract 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

public abstract 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

public abstract 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

public abstract 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

public abstract 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

public abstract 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

public 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.

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

public abstract 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