StorageVolume  |  API reference  |  Android Developers (original) (raw)

public final class StorageVolume
extends [Object](/reference/java/lang/Object) implements[Parcelable](/reference/android/os/Parcelable)

Information about a shared/external storage volume for a specific user.

A device always has one (and one only) primary storage volume, but it could have extra volumes, like SD cards and USB drives. This object represents the logical view of a storage volume for a specific user: different users might have different views for the same physical volume (for example, if the volume is a built-in emulated storage).

The storage volume is not necessarily mounted, applications should use [getState()](/reference/android/os/storage/StorageVolume#getState%28%29) to verify its state.

Applications willing to read or write to this storage volume needs to get a permission from the user first, which can be achieved in the following ways:

• To get access to standard directories (like the [Environment.DIRECTORY_PICTURES](/reference/android/os/Environment#DIRECTORY%5FPICTURES)), they can use the [createAccessIntent(String)](/reference/android/os/storage/StorageVolume#createAccessIntent%28java.lang.String%29). This is the recommend way, since it provides a simpler API and narrows the access to the given directory (and its descendants).
• To get access to any directory (and its descendants), they can use the Storage Access Framework APIs (such as [Intent.ACTION_OPEN_DOCUMENT](/reference/android/content/Intent#ACTION%5FOPEN%5FDOCUMENT) and[Intent.ACTION_OPEN_DOCUMENT_TREE](/reference/android/content/Intent#ACTION%5FOPEN%5FDOCUMENT%5FTREE), although these APIs do not guarantee the user will select this specific volume.
• To get read and write access to the primary storage volume, applications can declare the[Manifest.permission.READ_EXTERNAL_STORAGE](/reference/android/Manifest.permission#READ%5FEXTERNAL%5FSTORAGE) and[Manifest.permission.WRITE_EXTERNAL_STORAGE](/reference/android/Manifest.permission#WRITE%5FEXTERNAL%5FSTORAGE) permissions respectively, with the latter including the former. This approach is discouraged, since users may be hesitant to grant broad access to all files contained on a storage device.

It can be obtained through [StorageManager.getStorageVolumes()](/reference/android/os/storage/StorageManager#getStorageVolumes%28%29) and[StorageManager.getPrimaryStorageVolume()](/reference/android/os/storage/StorageManager#getPrimaryStorageVolume%28%29) and also as an extra in some broadcasts (see [EXTRA_STORAGE_VOLUME](/reference/android/os/storage/StorageVolume#EXTRA%5FSTORAGE%5FVOLUME)).

See [Environment.getExternalStorageDirectory()](/reference/android/os/Environment#getExternalStorageDirectory%28%29) for more info about shared/external storage semantics.

Summary

Constants

Fields

Public methods

createAccessIntent

public Intent createAccessIntent (String directoryName)

This method was deprecated in API level 29.
Callers should migrate to using [Intent.ACTION_OPEN_DOCUMENT_TREE](/reference/android/content/Intent#ACTION%5FOPEN%5FDOCUMENT%5FTREE) instead. Launching this [Intent](/reference/android/content/Intent) on devices running[Build.VERSION_CODES.Q](/reference/android/os/Build.VERSION%5FCODES#Q) or higher, will immediately finish with a result code of [Activity.RESULT_CANCELED](/reference/android/app/Activity#RESULT%5FCANCELED).

Builds an intent to give access to a standard storage directory or entire volume after obtaining the user's approval.

When invoked, the system will ask the user to grant access to the requested directory (and its descendants). The result of the request will be returned to the activity through theonActivityResult method.

To gain access to descendants (child, grandchild, etc) documents, use[DocumentsContract.buildDocumentUriUsingTree(Uri,String)](/reference/android/provider/DocumentsContract#buildDocumentUriUsingTree%28android.net.Uri,%20java.lang.String%29), or[DocumentsContract.buildChildDocumentsUriUsingTree(Uri,String)](/reference/android/provider/DocumentsContract#buildChildDocumentsUriUsingTree%28android.net.Uri,%20java.lang.String%29) with the returned URI.

If your application only needs to store internal data, consider using[Context.getExternalFilesDirs](/reference/android/content/Context#getExternalFilesDirs%28java.lang.String%29),[Context.getExternalCacheDirs()](/reference/android/content/Context#getExternalCacheDirs%28%29), or [Context.getExternalMediaDirs()](/reference/android/content/Context#getExternalMediaDirs%28%29), which require no permissions to read or write.

Access to the entire volume is only available for non-primary volumes (for the primary volume, apps can use the [Manifest.permission.READ_EXTERNAL_STORAGE](/reference/android/Manifest.permission#READ%5FEXTERNAL%5FSTORAGE) and[Manifest.permission.WRITE_EXTERNAL_STORAGE](/reference/android/Manifest.permission#WRITE%5FEXTERNAL%5FSTORAGE) permissions) and should be used with caution, since users are more likely to deny access when asked for entire volume access rather than specific directories.

createOpenDocumentTreeIntent

public Intent createOpenDocumentTreeIntent ()

Builds an [Intent.ACTION_OPEN_DOCUMENT_TREE](/reference/android/content/Intent#ACTION%5FOPEN%5FDOCUMENT%5FTREE) to allow the user to grant access to any directory subtree (or entire volume) from the [DocumentsProvider](/reference/android/provider/DocumentsProvider)s available on the device. The initial location of the document navigation will be the root of this [StorageVolume](/reference/android/os/storage/StorageVolume). Note that the returned [Intent](/reference/android/content/Intent) simply suggests that the user picks this [StorageVolume](/reference/android/os/storage/StorageVolume) by default, but the user may select a different location. Callers must respect the user's chosen location, even if it is different from the originally requested location.

describeContents

public int describeContents ()

Describe the kinds of special objects contained in this Parcelable instance's marshaled representation. For example, if the object will include a file descriptor in the output of [writeToParcel(Parcel,int)](/reference/android/os/Parcelable#writeToParcel%28android.os.Parcel,%20int%29), the return value of this method must include the[CONTENTS_FILE_DESCRIPTOR](/reference/android/os/Parcelable#CONTENTS%5FFILE%5FDESCRIPTOR) bit.

equals

public boolean equals (Object obj)

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference valuex, x.equals(x) should returntrue.
• It is symmetric: for any non-null reference valuesx and y, x.equals(y) should return true if and only ify.equals(x) returns true.
• It is transitive: for any non-null reference valuesx, y, and z, ifx.equals(y) returns true andy.equals(z) returns true, thenx.equals(z) should return true.
• It is consistent: for any non-null reference valuesx and y, multiple invocations ofx.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x,x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

getDescription

public String getDescription (Context context)

Returns a user-visible description of the volume.

getDirectory

public File getDirectory ()

Returns the directory where this volume is currently mounted.

Direct filesystem access via this path has significant emulation overhead, and apps are instead strongly encouraged to interact with media on storage volumes via the [MediaStore](/reference/android/provider/MediaStore) APIs.

This directory does not give apps any additional access beyond what they already have via [MediaStore](/reference/android/provider/MediaStore).

getOwner

public UserHandle getOwner ()

Returns the user that owns this volume

getUuid

public String getUuid ()

Gets the volume UUID, if any.

hashCode

public int hashCode ()

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by[HashMap](/reference/java/util/HashMap).

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the [equals](/reference/java/lang/Object#equals%28java.lang.Object%29) method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the [equals](/reference/java/lang/Object#equals%28java.lang.Object%29) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

isEmulated

public boolean isEmulated ()

Returns true if the volume is emulated.

isRemovable

public boolean isRemovable ()

Returns true if the volume is removable.

toString

public String toString ()

Returns a string representation of the object.