java - Get a DocumentFile that is a child of a document tree without using findFiles() -

i have tree uri got action_open_document_tree, how can documentfile child of tree without using findfiles()? given know how documentid, absolute path or uri. need permissions associated document tree.

this have right now:

documentfile roottree = documentfile.fromtreeuri(context, roottreeuri); documentfile docfile = roottree.findfile(filename); 

it returns docfile treedocumentfile, child of root. have write permission , can use createfile() on since under document tree action_open_document_tree.

so works findfile() slow.

if try use documentscontract so:

// know how build documentid file's absolute path uri uri = documentscontract.buildtreedocumenturi(roottreeuri.getauthority(), documentid); documentfile docfile = documentfile.fromtreeuri(context, uri); // result: "content://com.android.externalstorage.documents/tree/1a0e-0e2e:mychilddirectory/document/1a0e-0e2e:mychilddirectory" 

it returns new treedocumentfile rooted @ docfile, not docfile child of original document tree (root). don't have write permission on tree.

and if try so:

uri docuri = documentscontract.builddocumenturiusingtree(roottreeuri, documentid); // result: "content://com.android.externalstorage.documents/tree/1a0e-0e2e:/document/1a0e-0e2e:mychilddirectory" 

i uri looks want, it's uri, not documentfile.

if same above build documentfile uri fromtreeuri():

uri docuri = documentscontract.builddocumenturiusingtree(roottreeuri, documentid); documentfile docfile = documentfile.fromtreeuri(context, docuri); // result: "content://com.android.externalstorage.documents/tree/1a0e-0e2e:/document/1a0e-0e2e:" 

i original tree documentfile, not documentfile representing child.

what want not possible current apis. way make treedocumentfile (the private subclass of documentfile supports createfile, createdirectory, listfiles, , renameto) through documentfile.fromtreeuri (which gives root tree uri you've found) or through existing treedocumentfile's listfiles() method, findfile uses internally.

you should file feature request on issuetracker.google.com add new static method need.