Question

我有一个Runnable线程，每5秒刷新一次。这个线程想要写入以时间和日期命名的文件。

我检查文件是否存在，我想在现有文件上附加新更新，并在更改分钟时生成一个新文件，并每隔5秒对其执行相同的操作。

该应用程序基于JFrame申请表

Runnable helloRunnable = new Runnable(){

    @override
    public void run(){
        try{
            String FileName = Calendar.getInstance().get(Calendar.HOUR_OF_DAY) + Calendar.getInstance().get(Calendar.MINUTE) + ".txt";

            File f = new File(FileName);
            FileWriter filewriter = new FileWriter(FileName);
            BufferedWriter bufferedWriter = new BufferedWriter(filewriter);

            FileWriter filewriter2 = new FileWriter(f, true);
            BufferedWriter = bufferedWriter2 = new BufferedWriter(filewriter2);

            if (f.isFile() && !f.isDirectory()){ 
                bufferedWriter2.write("Hello"); //this part doesn't append "Hello" in file (as i want) but overwrite the existing file
                bufferedWriter2.close();
            }else{
                bufferedWriter.write("Hello"); //this part must overwrite the existing file so i think this work
                bufferedWriter.close();
            }

        } catch (IOExcception ex){
            Logger.getLogger(Gestionale.class.getName()).log(Level.SEVERE,nell,ex);
        }
    }
};
ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
SchedulateFuture<?> ez = executor.scheduleFixedRate(helloRunnable,0,5,TimeUnit.SECONDS);

Answer 1

您始终要实例化覆盖现有文件的FileWriter。

FileWriter filewriter = new FileWriter(FileName);

在此行之后，文件将始终为空您必须将FileWriter对象的创建移动到if语句中。

Java，FileWriter（file，true）不会附加到文件中

1 个答案: