从 class 保存到 sharedPrefs

Question

大家好，我有这段代码可以在 sharedprefs 中保存一些数据，但是 android studio 告诉我 "getDefaultSharedPrefs in Preference Manager cannot be applied to com.foo.downloadDB.AttemptLogin" 我该如何解决这个错误？

我好像无法从 "child" class 保存到我的 sharedprefs 这是代码：

public class downloadDB extends Activity  {

    private EditText user, pass;
    private android.widget.Button mSubmit, mRegister;

    // Progress Dialog
    private ProgressDialog pDialog;
    //JSON parser class
    JSONParser jsonParser = new JSONParser();

    //php login script location:

    //localhost :
    //testing on your device
    //put your local ip instead,  on windows, run CMD > ipconfig
    //or in mac's terminal type ifconfig and look for the ip under en0 or en1
    // private static final String LOGIN_URL = "http://xxx.xxx.x.x:1234/webservice/login.php";

    //testing on Emulator:
    private static final String LOGIN_URL = "http://www.myurl.com/users.php";

    //testing from a real server:
    //private static final String LOGIN_URL = "http://www.yourdomain.com/webservice/login.php";

    //JSON element ids from repsonse of php script:
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_MESSAGE = "message";



    @Override
    protected void onCreate (Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.download_db);
        new AttemptLogin().execute();


    }


   public class AttemptLogin extends AsyncTask<String, String, String>  {

        boolean failure = false;
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
        SharedPreferences.Editor editor1 = sharedPreferences.edit();

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(downloadDB.this);
            pDialog.setMessage("Download..");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        @Override
        protected String doInBackground(String...args) {


            //Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();


            Log.d("request!", "starting");
            // getting product details by making HTTP request
            JSONObject json = jsonParser.makeHttpRequest(
                    LOGIN_URL, "POST", params);

            //check your log for json response
            Log.d("Login attempt", json.toString());

            editor1.putString("JSON_DB", json.toString());
            editor1.commit();
            System.out.println(editor1.commit());

            return null;
        }

        // After completing background task Dismiss the progress dialog

        protected void onPostExecute(String file_url) {
            //dismiss the dialog once product deleted
            pDialog.dismiss();
            if (file_url != null) {
                Toast.makeText(downloadDB.this, file_url, Toast.LENGTH_LONG).show();
            }

            // Intent intent = new Intent(downloadDB.this, SampleActivity.class);
            // startActivity(intent);
        }
    }
}

编辑

我的 SampleActivity 中有这个方法 class

private void LoadPreferences(){
    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    String  name = sharedPreferences.getString("name", "0") ;
    String  email = sharedPreferences.getString("email", "0") ;
    String  id = sharedPreferences.getString("id", "0") ;
    String  Database = sharedPreferences.getString("JSON_DB", "0") ;
    Toast.makeText(this, Database, Toast.LENGTH_LONG).show();
    //Toast.makeText(this, id, Toast.LENGTH_LONG).show();
    //Toast.makeText(this, email, Toast.LENGTH_LONG).show();
}

Toast 工作正常，它正确地向我打印 JSON_DB，但是当我尝试从相应的 Fragment 访问它时它不起作用..这是我的片段代码：

public class SampleFragment extends Fragment {


    public static String KEY_ID = "id";
    public static String KEY_EMAIL = "email";
    public static String KEY_NAME = "name";
    public static String JSON_DB = "";

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        LoadPreferences();

        Log.i("string", KEY_EMAIL);
        Log.i("string", KEY_ID);
        Log.i("string", KEY_NAME);
        Log.i("string", JSON_DB);

和KEY_EMAIL、KEY_ID和其他对象正确记录..

Answer 1

这是问题所在：

SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

这是 AsyncTask 的实例，而不是 Activity

只用downloadDB.this代替这个；但请使用大写 (DownloadDB)

调用您的 class

从 class 保存到 sharedPrefs

Save in sharedPrefs from a class

javascript

java

android

sharedpreferences

android-studio