将联系人姓名解压缩到Xml文件中

Question

我想提取联系人姓名并将其放入xml文件中      //第一个提取联系人的方法

 private ArrayList<Contact> checkContacts() {
        ContentResolver cr = getActivity().getContentResolver();
        Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI, null, null, null, null);

        while (cur.moveToNext()) 
        {
            Contact newContact = new Contact();

        newContact.setName(getString(cur .getColumnIndex("ContactsContract.Contacts.DISPLAY_NAME")));

             myContactList.add(newContact);
        }   
        XmlContact();
        return (myContactList);
    }

//在这里我创建了我想放置联系人的xml文件

 private void XmlContact() {
    File newxmlfile = new File(Environment.getExternalStorageDirectory()+ "/ContactFile.xml");
    try
    {Log.v(BackupFragment.this.getClass().getName(), "create file:" + newxmlfile.createNewFile());} 
    catch (IOException e)
    {Log.e("IOException", "exception in createNewFile() method");}
    FileOutputStream fileos = null;
    try 
    {fileos = new FileOutputStream(newxmlfile);}
    catch (FileNotFoundException e) 
    {Log.e("FileNotFoundException", "can't create FileOutputStream");}
    XmlSerializer serializer = Xml.newSerializer();
    try {
        serializer.setOutput(fileos, "UTF-8");
        serializer.startDocument(null, Boolean.valueOf(true));

        serializer.setFeature("http://xmlpull.org/v1/doc/features.html#indent-output",true);
         serializer.startTag("", "Document");
        for(int i = 0 ; i < myContactList.size(); i++) {
            serializer.startTag("", "Contact");

             serializer.startTag(null, "name");
             serializer.text(myContactList.get(i).getName());
            serializer.endTag(null, "name");

            serializer.endTag("", "Contact");
        }
         serializer.endTag("", "Document");
        serializer.endDocument();
        serializer.flush();
        fileos.close();
    } catch (Exception e) {
        Log.e("Exception", "error occurred while creating xml file");
    }
}

该代码无效，我收到错误