private List<Integer> getMappedKeyFile(String txtFile){
        BufferedReader br = null;
        List<Integer> file1List = new ArrayList<Integer>();
        
        try {
            br = new BufferedReader(new FileReader(txtFile));
            String line = br.readLine();
            while (line != null) {
                Integer imageid = Integer.parseInt(line);
                file1List.add(imageid);
                line = br.readLine();
            }

        } catch (IOException ex) {
            Logger.getLogger(LSInSVD.class.getName()).log(Level.SEVERE, null, ex);
        }
        return file1List;
    }