安卓 如何 保存 edittext 的值

在 listview的item中有edittext的值 但是edittext定义在继承BaseAdapter外部类，我想设置edittext后保存他的值程序关闭后下次启动还能读出来，这样就必须把edittext的值存在fragment的onPause方法中，但是直接adapter里的edittext会报错空指针，求大神指点一下如何解决？

代码 贴出 ,说清楚点~

用shareperference

/**

• Created by bmvod on 2016/9/14.
  */
  public class HotSpotsListAdapter extends BaseAdapter {
  Context context;
  List list;
  public EditText edt_input_1, edt_input_2, edt_input_3, edt_input_4;
  public EditText hotspots_name_edit, hotspots_password_edit;

  public HotSpotsListAdapter(Context context, List list) {
  this.context = context;
  this.list = list;

  }

  @Override
  public int getCount() {
  return list.size();
  }

  @Override
  public Object getItem(int position) {
  return list.get(position);
  }

  @Override
  public long getItemId(int position) {
  return 0;
  }

  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
  LayoutInflater inflater = (LayoutInflater) context
  .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
  convertView = inflater.inflate(R.layout.network_hotspots_list_item, null);
  TextView text_left = (TextView) convertView.findViewById(R.id.hotspots_list_left_text);
  RelativeLayout relativeLayout = (RelativeLayout) convertView.findViewById(R.id.hotspots_item_content);
  relativeLayout.setBackgroundColor(Color.parseColor("#a7ffffff"));
  text_left.setText(list.get(position).toString());
  if (HotSpotsFragment.list_selected_position == position) {
  relativeLayout.setBackgroundColor(Color.WHITE);
  }
  TextView textView = (TextView) convertView.findViewById(R.id.hotspots_list_text);
  hotspots_name_edit = (EditText) convertView.findViewById(R.id.name_edit);
  hotspots_password_edit = (EditText) convertView.findViewById(R.id.password_edit);
  TextView point1 = (TextView) convertView.findViewById(R.id.point_1);
  TextView point2 = (TextView) convertView.findViewById(R.id.point_2);
  TextView point3 = (TextView) convertView.findViewById(R.id.point_3);
  edt_input_1 = (EditText) convertView.findViewById(R.id.ip_input_1);
  edt_input_2 = (EditText) convertView.findViewById(R.id.ip_input_2);
  edt_input_3 = (EditText) convertView.findViewById(R.id.ip_input_3);
  edt_input_4 = (EditText) convertView.findViewById(R.id.ip_input_4);
  WriteUserInfo();
  SharedPreferences read = context.getSharedPreferences("user_hotspots_detect", Context.MODE_PRIVATE);
  String ip_input1 = read.getString("edt_ip_input1", "");
  String ip_input2 = read.getString("edt_ip_input2", "");
  String ip_input3 = read.getString("edt_ip_input3", "");
  String ip_input4 = read.getString("edt_ip_input4", "");
  String name = read.getString("edt_name", "");
  String password = read.getString("edt_password", "");
  switch (position) {
  case 0:
  edt_input_1.setVisibility(View.GONE);
  edt_input_2.setVisibility(View.GONE);
  edt_input_3.setVisibility(View.GONE);
  edt_input_4.setVisibility(View.GONE);
  hotspots_name_edit.setText(name);
  break;
  case 1:
  edt_input_1.setText(ip_input1);
  edt_input_2.setText(ip_input2);
  edt_input_3.setText(ip_input3);
  edt_input_4.setText(ip_input4);
  point1.setText(".");
  point2.setText(".");
  point3.setText(".");
  break;
  case 2:
  textView.setText("固定");
  edt_input_1.setFocusable(false);
  edt_input_2.setFocusable(false);
  edt_input_3.setFocusable(false);
  edt_input_4.setFocusable(false);
  break;
  case 3:

          hotspots_password_edit.setText(password);
          edt_input_1.setVisibility(View.GONE);
          edt_input_2.setVisibility(View.GONE);
          edt_input_3.setVisibility(View.GONE);
          edt_input_4.setVisibility(View.GONE);
          break;
      case 4:
          textView.setText("启用");
          edt_input_1.setVisibility(View.GONE);
          edt_input_2.setVisibility(View.GONE);
          edt_input_3.setVisibility(View.GONE);
          edt_input_4.setVisibility(View.GONE);
          break;
  }
  
  return convertView;
  

  }

  public void WriteUserInfo() {
  SharedPreferences userdetect = context.getSharedPreferences("user_hotspots_detect", 0);
  SharedPreferences.Editor editor = userdetect.edit();

  editor.putString("edt_ip_input1", edt_input_1.getText().toString());
  editor.putString("edt_ip_input2", edt_input_2.getText().toString());
  editor.putString("edt_ip_input3", edt_input_2.getText().toString());
  editor.putString("edt_ip_input4", edt_input_4.getText().toString());
  editor.putString("edt_name", hotspots_name_edit.getText().toString());
  editor.putString("edt_password", hotspots_password_edit.getText().toString());
  editor.commit();
  

  }
  }