How to select all checkbox in a website with java

I want to ask a question. I have to download several data from a website but some data failed when downloading. So I do the search on that website and if i want to download it successfully, I have to select all the check box. So actually I download it automatically with Java, how can I select all the check box before download?

List<Path> files = Component.makePathList(Paths.get(url));
        List<Thread> threads = new ArrayList<Thread>();
        List<String> alinks = new ArrayList<String>();
        try {
            for (Path file : files) {
                filePos = file.toFile().getName();
                List<String> links = Files.readAllLines(file);
                alinks.addAll(links);
                for (int i = 0; i < links.size(); i++) {
                    String fileName = Component.matches("[0-9]{3,}", links.get(i)).concat(".html");
                    String destination = desHTMLFile.concat("\\"+fileName);
                    WipoDownloadHTMLHelper helper = new WipoDownloadHTMLHelper(destination, links.get(i));
                    Thread a = new Thread(helper);
                    a.start();
                    linePos = i;
                    threads.add(a);
                    if (threads.size() % 100 == 0) {
                        System.out.println(threads.size() % 100);
                        threads = cleanThreads(threads);
                        Thread.sleep(10000);
                        System.gc();
                        continue;
                    }
                    Thread.sleep(5000);
                }
                threads = cleanThreads(threads);
                System.gc();
            }
            System.out.println("FILES NAME is " + this.filePos);
            System.out.println("Lines is " + this.linePos);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
            System.err.println("FILES NAME is " + this.filePos);
            System.err.println("Lines is " + this.linePos);
        }