我有一个ArrayList列表编写器，我使用此AsyncTask填充。
class LoadAllGamesWhenNull extends AsyncTask<String, String, String> {
private String id;
private String stake;
private String user;
private String returns;
private String teams;
private String status;
// *//**
// * Before starting background thread Show Progress Dialog
// *//*
@Override
protected void onPreExecute() {
super.onPreExecute();
}
// *//**
// * getting All products from url
// *//*
protected String doInBackground(String... args) {
// Building Parameters
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(url_all_games);
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("email", name));
try {
post.setEntity(new UrlEncodedFormEntity(params));
} catch (IOException ioe) {
ioe.printStackTrace();
}
try {
HttpResponse response = client.execute(post);
Log.d("Http Post Response:", response.toString());
HttpEntity httpEntity = response.getEntity();
InputStream is = httpEntity.getContent();
JSONObject jObj = null;
String json = "";
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
if (!line.startsWith("<", 0)) {
if (!line.startsWith("(", 0)) {
sb.append(line + "\n");
}
}
}
is.close();
json = sb.toString();
json = json.substring(json.indexOf('{'));
Log.d("sb", json);
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
Log.d("json", jObj.toString());
try {
allgames = jObj.getJSONArray(TAG_BET);
Log.d("allgames", allgames.toString());
ArrayList<BetDatabaseSaver> listofbets = new ArrayList<>();
// looping through All Products
for (int i = 0; i < allgames.length(); i++) {
JSONObject c = allgames.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_ID);
String user = c.getString(TAG_USER);
String returns = c.getString(TAG_RETURNS);
String stake = c.getString(TAG_STAKE);
String status = c.getString(TAG_STATUS);
String Teams = c.getString(TAG_TEAMS);
Log.d("id", id);
Log.d("user", user);
Log.d("returns", returns);
Log.d("stake", stake);
Log.d("status", status);
Log.d("teams", Teams);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_ID, id);
map.put(TAG_TEAMS, Teams);
map.put(TAG_USER, user);
map.put(TAG_RETURNS, returns);
map.put(TAG_STAKE, stake);
map.put(TAG_STATUS, status);
if (status.equals("open")) {
useroutcomes.put(id.substring(0, 10), Teams);
}
listwriter.add(i, new BetDisplayer(user, id, Integer.parseInt(stake), Integer.parseInt(returns), status, "","",Teams));
Log.d("map", map.toString());
// adding HashList to ArrayList
bet.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
} catch (IOException ioe) {
ioe.printStackTrace();
}
return "";
}
@Override
protected void onPostExecute(String param) {
// dismiss the dialog after getting all products
// updating UI from Background Thread
String ultparam = "";
int i = 0;
for (HashMap<String, String> a : bet) {
String teams = a.get(TAG_TEAMS);
Map<String, String> listofteams = new HashMap<>();
Pattern p = Pattern.compile("[(](\\d+)/([1X2])[)]");
Matcher m = p.matcher(teams);
Log.d("printa", teams);
while (m.find()) {
listofteams.put(m.group(1), m.group(2));
}
Log.d("dede", listofteams.toString());
String c = "";
for (String x : listofteams.keySet()) {
String b = x + ",";
c = c + b;
}
Log.d("C", c);
c = c.substring(0, c.lastIndexOf(","));
// Log.d("Cproc", c);
ultparam = ultparam + a.get(TAG_ID).substring(0, 10) + c + "//";
passtocheck.add(listofteams);
allopens.put(Integer.toString(i), a.get(TAG_STATUS));
i++;
i++;
}
ultparam = ultparam.substring(0, ultparam.lastIndexOf("//"));
Log.d("ULTPARAM", ultparam);
CheckBet checker = new CheckBet(ultparam, passtocheck);
HashMap<String, String> finaloutcomes = checker.checkbetoutcome();
Log.d("Finaloutcomes", finaloutcomes.toString());
finaloutcomess = finaloutcomes.toString();
for (String x : finaloutcomes.keySet()) {
for (int p = 0; p < listwriter.size(); p++) {
if (listwriter.get(p).getId().substring(0, 10).equals(x)) {
String[] finaloutcomearray = finaloutcomes.get(x).split(" ");
String[] useroutcomearray = listwriter.get(p).getSelections().split(" ");
for (int r = 0; r < finaloutcomearray.length; r++) {
Log.d("finaloutcomearray", finaloutcomearray[r]);
Log.d("useroutcomearray", useroutcomearray[r]);
String[] indfinaloutcomesarray = finaloutcomearray[r].split("\\)");
String[] induseroutcomearray = useroutcomearray[r].split("\\)");
for (int d = 0; d < indfinaloutcomesarray.length; d++) {
Log.d("indfinaloutcome", indfinaloutcomesarray[d]);
Log.d("induseroutcome", induseroutcomearray[d]);
finalhash.put(indfinaloutcomesarray[d].substring(1, indfinaloutcomesarray[d].lastIndexOf("/")), indfinaloutcomesarray[d].substring(indfinaloutcomesarray[d].lastIndexOf("/") + 1));
userhash.put(induseroutcomearray[d].substring(1, induseroutcomearray[d].lastIndexOf("/")), induseroutcomearray[d].substring(induseroutcomearray[d].lastIndexOf("/") + 1));
}
}
Log.d("FINALHASHfinal", finalhash.toString());
listwriter.get(p).setActualselections(finalhash.toString());
listwriter.get(p).setUserselections(userhash.toString());
Log.d("USERHASHfinal", userhash.toString());
listwriter.get(p).setStatus("won");
for (String id : userhash.keySet()) {
if (finalhash.get(id).equals("null")) {
listwriter.get(p).setStatus("open");
} else if (!(finalhash.get(id).equals(userhash.get(id)))) {
listwriter.get(p).setStatus("lost");
break;
}
}
finalhash.clear();
userhash.clear();
currentitem = listwriter.get(p);
if (currentitem.getStatus().equals("open")) {
} else {
if (currentitem.getStatus().equals("won")) {
valuechange = valuechange + currentitem.getReturns() - (currentitem.getStake());
}
String c = currentitem.getId() + "," + currentitem.getStatus() + "//";
updateparam = updateparam + c;
Log.d("UPDATEPARAM1", updateparam);
}
}
}
}
Log.d("Listwriterbefore",listwriter.toString());
session.setListwriter(listwriter);
new UpdateBetStatus().execute();
Intent g = new Intent(loadingscreen.this,DisplayAllBets.class);
startActivity(g);
finish();
}}
这是在我的加载屏Activity上完成的，我想将列表编写器设置为SharedPreferences，以便我可以在另一个Activity中使用它。这是我的会话管理器类。 AsyncTask中的日志记录向我显示列表编写器已正确填充。但是，当我在其他课程中调用getlistwriter时，我收到一个空的ArrayList。我无法看到错误的位置。
public class SessionManager {
// LogCat tag
private static String TAG = SessionManager.class.getSimpleName();
private ArrayList<BetDisplayer> listwriter = new ArrayList<>();
// Shared Preferences
SharedPreferences pref;
Editor editor;
Context _context;
// Shared pref mode
int PRIVATE_MODE = 0;
// Shared preferences file name
private static final String PREF_NAME = "AndroidHiveLogin";
private static final String KEY_IS_LOGGEDIN = "isLoggedIn";
public static final String USERNAME = "username";
public SessionManager(Context context) {
this._context = context;
pref = _context.getSharedPreferences(PREF_NAME, PRIVATE_MODE);
editor = pref.edit();
}
public ArrayList<BetDisplayer> getListwriter() {
return listwriter;
}
public void setListwriter(ArrayList<BetDisplayer> listwriter) {
this.listwriter = listwriter;
}
public void setLogin(boolean isLoggedIn, String username) {
editor.putBoolean(KEY_IS_LOGGEDIN, isLoggedIn);
editor.putString(USERNAME, username);
// commit changes
editor.commit();
Log.d(TAG, "User login session modified!");
}
public HashMap<String, String> getUserDetails(){
HashMap<String, String> user = new HashMap<String, String>();
// user name
user.put(USERNAME, pref.getString(USERNAME, null));
// return user
return user;
}
public boolean isLoggedIn(){
return pref.getBoolean(KEY_IS_LOGGEDIN, false);
}}
用于检索列表编写器的代码
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_display_all_bets);
menu menu = (menu)
getFragmentManager().findFragmentById(R.id.fragment);
menu.updateinfo(getName());
session = new SessionManager(getApplicationContext());
HashMap<String, String> user = session.getUserDetails();
name = user.get(SessionManager.USERNAME);
listwriter = session.getListwriter();
AppController类：
public class AppController extends Application {
public static final String TAG = AppController.class.getSimpleName();
private RequestQueue mRequestQueue;
private static AppController mInstance;
private ArrayList<HashMap<String, String>> gamesList;
public ArrayList<HashMap<String, String>> getGamesList() {
return gamesList;
}
public void setGamesList(ArrayList<HashMap<String, String>> gamesList) {
this.gamesList = gamesList;
}
@Override
public void onCreate() {
super.onCreate();
mInstance = this;
}
public static synchronized AppController getInstance() {
return mInstance;
}
public RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
mRequestQueue = Volley.newRequestQueue(getApplicationContext());
}
return mRequestQueue;
}
public <T> void addToRequestQueue(Request<T> req, String tag) {
req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
getRequestQueue().add(req);
}
public <T> void addToRequestQueue(Request<T> req) {
req.setTag(TAG);
getRequestQueue().add(req);
}
public void cancelPendingRequests(Object tag) {
if (mRequestQueue != null) {
mRequestQueue.cancelAll(tag);
}
}
答案 0 :(得分：2)
在您的SessionManager中，您未将List保存到SharedPrefs。你应该这样做：
public static final String MY_LIST = "my_list";
private static final Type LIST_TYPE = new TypeToken<List<BetDisplayer>>() {}.getType();
保存：
public void setListwriter(ArrayList<BetDisplayer> listwriter) {
this.listwriter = new ArrayList<BetDisplayer>(listwriter);
mPrefs.edit()
.putString(MY_LIST, new Gson().toJson(listwriter));
.commit();
}
加载：
public ArrayList<BetDisplayer> getListwriter() {
if (listwriter == null) {
listwriter = new Gson().fromJson(mPrefs.getString(MY_LIST, null), LIST_TYPE);
if(listwriter == null){
listwriter = new ArrayList<BetDisplayer>();
}
}
return listwriter;
}
您的BetDisplayer必须implements Serializable
见这里：Android array to Sharedpreferences with Gson
要使用Gson，只需添加此依赖项：'com.google.code.gson：gson：2.3.1'或下载.jar
<强>更新
创建一个仅Singleton仅包含SharedPreferences编辑器的Singleton，这只是猜测但我认为您使用不同的上下文来获取编辑器，这可能是问题所在（更新2 ：不是，请检查here，但private static SharedPreferences mPrefs;
private static SessionManager sInstance = null;
protected SessionManager() {
mPrefs = AppController.getInstance().getApplicationContext().getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE);
}
public static SessionManager getInstance() {
if (sInstance == null) {
sInstance = new SessionManager();
}
return sInstance;
}
接近它是一个加号：
SharedPreferences当您需要使用SessionManager().getInstance().someMethod();时使用{{1}}