DocumentFile
public abstract class DocumentFile
Representation of a document backed by either a android.provider.DocumentsProvider or a raw file on disk. This is a utility class designed to emulate the traditional File interface. It offers a simplified view of a tree of documents, but it has substantial overhead. For optimal performance and a richer feature set, use the android.provider.DocumentsContract methods and constants directly.
There are several differences between documents and traditional files:
- Documents express their display name and MIME type as separate fields, instead of relying on file extensions. Some documents providers may still choose to append extensions to their display names, but that's an implementation detail.
- A single document may appear as the child of multiple directories, so it doesn't inherently know who its parent is. That is, documents don't have a strong notion of path. You can easily traverse a tree of documents from parent to child, but not from child to parent.
- Each document has a unique identifier within that provider. This identifier is an opaque implementation detail of the provider, and as such it must not be parsed.
Before using this class, first consider if you really need access to an entire subtree of documents. The principle of least privilege dictates that you should only ask for access to documents you really need. If you only need the user to pick a single file, use ACTION_OPEN_DOCUMENT or ACTION_GET_CONTENT. If you want to let the user pick multiple files, add EXTRA_ALLOW_MULTIPLE. If you only need the user to save a single file, use ACTION_CREATE_DOCUMENT. If you use these APIs, you can pass the resulting getData into fromSingleUri to work with that document.
If you really do need full access to an entire subtree of documents, start by launching ACTION_OPEN_DOCUMENT_TREE to let the user pick a directory. Then pass the resulting getData into fromTreeUri to start working with the user selected tree.
As you navigate the tree of DocumentFile instances, you can always use getUri to obtain the Uri representing the underlying document for that object, for use with openInputStream, etc.
To simplify your code on devices running KITKAT or earlier, you can use fromFile which emulates the behavior of a android.provider.DocumentsProvider.
| See also | |
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DocumentsProvider |
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DocumentsContract |
Summary
Public methods |
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abstract boolean |
canRead()Indicates whether the current context is allowed to read from this file. |
abstract boolean |
canWrite()Indicates whether the current context is allowed to write to this file. |
abstract @Nullable DocumentFile |
createDirectory(@NonNull String displayName)Create a new directory as a direct child of this directory. |
abstract @Nullable DocumentFile |
createFile(@NonNull String mimeType, @NonNull String displayName)Create a new document as a direct child of this directory. |
abstract boolean |
delete()Deletes this file. |
abstract boolean |
exists()Returns a boolean indicating whether this file can be found. |
@Nullable DocumentFile |
Search through |
static @NonNull DocumentFile |
Create a |
static @Nullable DocumentFile |
fromSingleUri(@NonNull Context context, @NonNull Uri singleUri)Create a |
static @Nullable DocumentFile |
fromTreeUri(@NonNull Context context, @NonNull Uri treeUri)Create a |
abstract @Nullable String |
getName()Return the display name of this document. |
@Nullable DocumentFile |
Return the parent file of this document. |
abstract @Nullable String |
getType()Return the MIME type of this document. |
abstract @NonNull Uri |
getUri()Return a Uri for the underlying document represented by this file. |
abstract boolean |
Indicates if this file represents a directory. |
static boolean |
isDocumentUri(@NonNull Context context, @Nullable Uri uri)Test if given Uri is backed by a |
abstract boolean |
isFile()Indicates if this file represents a file. |
abstract boolean |
Indicates if this file represents a virtual document. |
abstract long |
Returns the time when this file was last modified, measured in milliseconds since January 1st, 1970, midnight. |
abstract long |
length()Returns the length of this file in bytes. |
abstract @NonNull DocumentFile[] |
Returns an array of files contained in the directory represented by this file. |
abstract boolean |
Renames this file to |
Public methods
canRead
public abstract boolean canRead()
Indicates whether the current context is allowed to read from this file.
| Returns | |
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boolean |
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canWrite
public abstract boolean canWrite()
Indicates whether the current context is allowed to write to this file.
| Returns | |
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boolean |
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createDirectory
public abstract @Nullable DocumentFile createDirectory(@NonNull String displayName)
Create a new directory as a direct child of this directory.
| Returns | |
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@Nullable DocumentFile |
file representing newly created directory, or null if failed |
| Throws | |
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java.lang.UnsupportedOperationException |
when working with a single document created from |
| See also | |
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createDocument |
createFile
public abstract @Nullable DocumentFile createFile(@NonNull String mimeType, @NonNull String displayName)
Create a new document as a direct child of this directory.
| Parameters | |
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@NonNull String mimeType |
MIME type of new document, such as |
@NonNull String displayName |
name of new document, without any file extension appended; the underlying provider may choose to append the extension |
| Returns | |
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@Nullable DocumentFile |
file representing newly created document, or null if failed |
| Throws | |
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java.lang.UnsupportedOperationException |
when working with a single document created from |
| See also | |
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createDocument |
delete
public abstract boolean delete()
Deletes this file.
Note that this method does not throw IOException on failure. Callers must check the return value.
| Returns | |
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boolean |
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| See also | |
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deleteDocument |
exists
public abstract boolean exists()
Returns a boolean indicating whether this file can be found.
| Returns | |
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boolean |
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findFile
public @Nullable DocumentFile findFile(@NonNull String displayName)
Search through listFiles for the first document matching the given display name. Returns null when no matching document is found.
| Throws | |
|---|---|
java.lang.UnsupportedOperationException |
when working with a single document created from |
fromFile
public static @NonNull DocumentFile fromFile(@NonNull File file)
Create a DocumentFile representing the filesystem tree rooted at the given File. This doesn't give you any additional access to the underlying files beyond what your app already has.
getUri will return file:// Uris for files explored through this tree.
fromSingleUri
public static @Nullable DocumentFile fromSingleUri(@NonNull Context context, @NonNull Uri singleUri)
Create a DocumentFile representing the single document at the given Uri. This is only useful on devices running KITKAT or later, and will return null when called on earlier platform versions.
| Parameters | |
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@NonNull Context context |
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@NonNull Uri singleUri |
the |
fromTreeUri
public static @Nullable DocumentFile fromTreeUri(@NonNull Context context, @NonNull Uri treeUri)
Create a DocumentFile representing the document tree rooted at the given Uri. This is only useful on devices running LOLLIPOP or later, and will return null when called on earlier platform versions.
getName
public abstract @Nullable String getName()
Return the display name of this document.
| See also | |
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COLUMN_DISPLAY_NAME |
getParentFile
public @Nullable DocumentFile getParentFile()
Return the parent file of this document. Only defined inside of the user-selected tree; you can never escape above the top of the tree.
The underlying android.provider.DocumentsProvider only defines a forward mapping from parent to child, so the reverse mapping of child to parent offered here is purely a convenience method, and it may be incorrect if the underlying tree structure changes.
getType
public abstract @Nullable String getType()
Return the MIME type of this document.
| See also | |
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COLUMN_MIME_TYPE |