java.lang.ClassCastException：java.util.ArrayList无法强制转换为java.lang.String，array [[file-1519428262786.pdf，Leistungen.pdf]]

Question

List<String> files = (List<String>) getArguments().getSerializable("file");
    assert files != null;
        fileName = files.get(0);//String fileName
        fileName = fileName.replace("[", "");
        fileName = fileName.replace("]", "");
    remotePDFViewPager = new RemotePDFViewPager(getActivity(),
            APIClient.FILE_URL + fileName, this);
    pdfViewLinearLayout.setBackgroundColor(Color.BLACK);

我需要获取数组的第一项：[[file-1519428262786.pdf，Leistungen.pdf]]，即file-1519428262786.pdf

Answer 1

List<ArrayList<String>> filesArray =
   (List<ArrayList<String>>) getArguments().getSerializable("file");
ArrayList<String> nestedFile = filesArray.get(0);