Create new file in the directory returned by Intent.ACTION_OPEN_DOCUMENT_TREE

In my App the user can choose a directory where to create an Excel file using the implicit intent ACTION_OPEN_DOCUMENT_TREE.
However, the Uri returned in onActivityResult() cannot be used by FileOutputStream(). It throws a FileNotFoundException:

java.io.FileNotFoundException: content:/com.android.externalstorage.documents/tree/home%3A:test.xlsx (No such file or directory)

In onActivityResult() I check if the path exists via File.exists() and if not, I want to create a new Excel file.

onActivityResult():

	@Override
	protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
		Log.d(TAG, "onActivityResult: called");
		super.onActivityResult(requestCode, resultCode, data);
		if (resultCode == Activity.RESULT_OK && requestCode == 2) {
			Log.d(TAG, "onActivityResult: path = " + data.getData()
			                                             .getPath());
			Uri treePath = data.getData();
			File path = new File(treePath + File.pathSeparator + "test.xlsx");
			if (path.exists()) {
				updateExistingExcelFile(path);
			} else {
				createNewExcelFile(path);
			}
		}
	}

createNewExcelFile():

	private void createNewExcelFile(File path) {
		Log.d(TAG, "createNewExcelFile: called");
		Workbook workbook = new HSSFWorkbook();
		Cell cell;
		Sheet sheet;
		sheet = workbook.createSheet("Name of sheet");
		Row row = sheet.createRow(0);
		cell = row.createCell(0);
		cell.setCellValue("Name");
		cell = row.createCell(1);
		cell.setCellValue("Number");
		sheet.setColumnWidth(0, (10 * 200));
		sheet.setColumnWidth(1, (10 * 200));
		FileOutputStream fileOutputStream;
		try {
			fileOutputStream = new FileOutputStream(path);
			workbook.write(fileOutputStream);
			Toast.makeText(this, "Created", Toast.LENGTH_LONG)
			     .show();
			fileOutputStream.close();
		} catch (IOException e) {
			Log.e(TAG, "createNewExcelFile: ", e);
		}
	}

The code works perfectly fine if I use Activity.getExternalFilesDir(Environment.DIRECTORY_DOCUMENTS) or something similar instead of the implicit intents path.

Step #1: Take the Uri that you get from ACTION_OPEN_DOCUMENT_TREE and pass it to DocumentFile.fromTreeUri().

Step #2: Call createFile() on that DocumentFile to get a DocumentFile representing the child document.

Step #3: Call getUri() on the DocumentFile that you created in Step #2.

Step #4: Call openOutputStream() on a ContentResolver, passing in the Uri from Step #3, to get an OutputStream that you can use to write content. You get a ContentResolver by calling getContentResolver() on some Context, such as an Activity.

See this blog post for more on using ACTION_OPEN_DOCUMENT_TREE.