问如何在存储访问框架中显示Toast？

EN

 public void openFile() {
    Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
    intent.addCategory(Intent.CATEGORY_OPENABLE);
    intent.setType("text/plain");
    startActivityForResult(intent, OPEN_REQUEST_CODE);
}

private String readFileContent(Uri uri) throws IOException {

    InputStream inputStream =
            getContentResolver().openInputStream(uri);
    BufferedReader reader =
            new BufferedReader(new InputStreamReader(
                    inputStream));
    StringBuilder stringBuilder = new StringBuilder();
    String currentline;
    while ((currentline = reader.readLine()) != null) {
        stringBuilder.append(currentline + "\n");
    }
    inputStream.close();
    return stringBuilder.toString();
}