java - FTPClient 和 BufferedReader

Question

所以我有这段代码应该从 ftp 目录中的每个文本文档的每一行读取，问题是它只适用于 det 第一个文件，因为当涉及到第二个文件时，我可以在日志中看到second 也被列出但是当它想要阅读它时它就崩溃了，这就是代码

public void getComments(){
        final FTPClient ftpClient = new FTPClient();
        BufferedReader reader = null;

        new Thread(new Runnable() {
            public void run() {
        try {
            ftpClient.connect(InetAddress.getByName("31.220.17.2"));
            ftpClient.login("mopedsho", "neppi1");
            int imageNr = sharedPreferences.getInt("ImageNrCross", 1);
            ftpClient.makeDirectory("/public_ftp/Comments/Cross/" + imageNr);
                    ftpClient.changeWorkingDirectory("/public_ftp/Comments/Cross/" + imageNr);
            String[] names = ftpClient.listNames();
            if (names == null) {


            } else {
                BufferedReader reader = null;
                for (String name : names) {
                    if (!name.equals(".") && !name.equals("..")) {
                        InputStream in = null;
                        try {
                            Log.e("File namer", name + "");

                            in = ftpClient.retrieveFileStream(name);
                            if (in != null) {
                                reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));
                                String firstLine;
                                while ((firstLine = reader.readLine()) != null) {
                                    final String line = firstLine;
                                    Handler handler = new Handler(Looper.getMainLooper());
                                    handler.post(new Runnable() {

                                        @Override
                                        public void run() {
                                            adapter.add("" + line);

                                        }

                                    });

                                }
                            }
                            in.close();

                        } catch (UnsupportedEncodingException e) {
                            e.printStackTrace();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }

                    }
                    ftpClient.logout();
                    ftpClient.disconnect();
                }
            }} catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (SocketException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }}
        }).start();}

错误代码:

07-14 13:50:27.739  20152-20298/com.emiliogaines.mopedshowcase E/File namer﹕ EmilioGaines4663767201961631433982.txt
07-14 13:50:28.166  20152-20298/com.emiliogaines.mopedshowcase E/File namer﹕ EmilioGaines4663767201961631535180.txt
07-14 13:50:28.306  20152-20298/com.emiliogaines.mopedshowcase E/AndroidRuntime﹕ FATAL EXCEPTION: Thread-6657
    Process: com.emiliogaines.mopedshowcase, PID: 20152
    java.lang.NullPointerException: lock == null
            at java.io.Reader.<init>(Reader.java:64)
            at java.io.InputStreamReader.<init>(InputStreamReader.java:77)
            at com.emiliogaiines.mopedshowcase.commentLayout$2.run(commentLayout.java:140)
            at java.lang.Thread.run(Thread.java:818)
07-14 13:50:28.431  20152-20152/com.emiliogaines.mopedshowcase I/Ti

错误指向这一行

reader = new BufferedReader(new InputStreamReader(in, "UTF-8"));

Answer 1

in = ftpClient.retrieveFileStream(name);

此行向您返回一个输入流，该输入流为空或未正确实例化。所以请检查那个 perticuler 方法，总是最好使用 null 检查，比如

if(in != null)

如果您仍然遇到相同的异常，请提供上述方法代码，以便我们解决。