将 ArrayList 复制到外部存储

保存到首选项：

SharedPreferences prefs;
ArrayList<String> myList; //лист который надо сохранить
//blah-blah
SharedPreferences.Editor editor=prefs.edit();
Set<String> sets=new HashSet<String>(myList); //конвертируем в Set<>
editor.putStringSet("myList", sets); //пихаем сет в префы
editor.commit(); //записываем

首先找到最外层的存储：

File externalRootDir = Environment.getExternalStorageDirectory();

然后在其中创建一个文件：

File logFile = new File(externalRootDir , "Log.txt");

接下来，将内容写入其中ArrayList：

try (PrintWriter printWriter = new PrintWriter(logFile)) {
    for (String data : dataList) {
        printWriter.println(data);
    }
}

更新：

该构造try-with-resources出现在 Java 7 中。在较小的版本中，您可以这样做：

PrintWriter printWriter = null;

try {
    printWriter = new PrintWriter(logFile);
    for (String data : dataList) {
        printWriter.println(data);
    }
} catch (FileNotFoundException e) {
    e.printStackTrace();
} finally {
    if (printWriter != null) {
        printWriter.close();
    }
}

FileOutputStream os = null; try { os = new FileOutputStream(Environment.getExternalStorageDirectory().getPath()+"/sample.txt"); os.write(dataToSave); os.flush(); os.close(); } catch (IOException e) { e.printStackTrace(); }