读取文件 Android 时非常奇怪的 NullPointerException

Question

代码如下：

Thread clientThread = new Thread() {
            @Override
            public void run() {
                try {
                    client = new Client();
                    quest = client.readFile();
                    Log.v("Client string", quest);

                    //File file = new File(myContext.getFilesDir(), "questionnaire.xml");
                    //BufferedWriter bw = new BufferedWriter(new FileWriter(file));
                    //bw.write(quest);
                    File tempFile = File.createTempFile("questionnaire", ".xml");
                    FileOutputStream fout = new FileOutputStream(tempFile);
                    PrintStream out = new PrintStream(fout);
                    out.println(quest);//InputStream stream = new ByteArrayInputStream(quest.getBytes("UTF-8"));
                    //getResources().op
                    try {
                    Serializer serializer = new Persister();
                    responseToQuestionnaire = serializer.read(ResponseToQuestionnaire.class, tempFile);
                    }
                    catch(Exception e) {}
                    Log.v("Let's seeeeee",responseToQuestionnaire.getQuestionnaireTemplate().toString());

                } catch (Exception e1) {
                    e1.printStackTrace();
                }
//              try {
//                  OutputStreamWriter outputStreamWriter = new OutputStreamWriter(
//                          openFileOutput(currentQuestionnaire.getName(),
//                                  Context.MODE_PRIVATE));
//                  outputStreamWriter.write(client.readFile());
//                  outputStreamWriter.close();
//              } catch (IOException e) {
//                  Log.e("Exception", "File write failed: " + e.toString());
//              }
            }
        };
        clientThread.start();

即使 quest 是在日志中完美打印的全长字符串，代码也会引发空指针异常。我尝试了多种保存文件的方法，但 SimpleXML 不序列化字符串......只有 XML 文件。

Answer 1

缓冲流不一定会写入数据，直到必须这样做。在调用 read() 方法之前尝试关闭输出流。