Android中的java.util.ConcurrentModificationException

我正在编写一段代码，该代码使用来自AsyncTask和预定义HashMap的信息显示在可扩展列表中。但是它抛出了java.util.ConcurrentModificationException。我的代码如下：

阿斯尼茨克

private class BackTask extends AsyncTask<Void, Void, Void> {
        ProgressDialog pd;
        ArrayList<String> name;
        ArrayList<Integer> quantity;
        Map<String, Map<String, Integer>> cart_names1 = new HashMap<String, Map<String, Integer>>();

        public BackTask(ArrayList<String> name, ArrayList<Integer> quantity) {
            this.name = name;
            this.quantity = quantity;
        }

        protected void onPreExecute() {

            super.onPreExecute();

            pd = new ProgressDialog(ha);

            pd.setTitle("Retrieving data");

            pd.setMessage("Please wait.");

            pd.setCancelable(true);

            pd.setIndeterminate(true);

            pd.show();


        }

        protected Void doInBackground(Void... arg0) {
            InputStream is = null;
            String result = "";
            try {
                String link = "http://chutte.co.nf/get_item_prices.php?";
                for (int b = 0; b < name.size(); b++) {
                    link += "names[]" + "=" + name.get(b) + "&";

                }
                for (int a = 0; a < quantity.size(); a++) {
                    link += "quantities[]" + "=" + quantity.get(a);
                    if (a != quantity.size() - 1) {
                        link += "&";
                    }
                }
                Log.e("ERROR", link);
                URL url = new URL(link);
                HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
                is = urlConnection.getInputStream();
            } catch (Exception e) {
                if (pd != null) pd.dismiss();


                Log.e("ERROR", e.getMessage());
            }
            try {
                BufferedReader reader = new BufferedReader(new InputStreamReader(is));
                StringBuilder builder = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null) {
                    builder.append(line + "\n");

                }
                is.close();
                result = builder.toString();
            } catch (Exception e) {
                Log.e("ERROR", "Error converting result " + e.toString());
            }
            try {
                result = result.substring(result.indexOf("["));
                JSONArray jsonArray = new JSONArray(result);
                for (int i = 0; i < jsonArray.length(); i++) {
                    JSONObject jsonObject = jsonArray.getJSONObject(i);
                    Map<String, Integer> temmap = new HashMap<>();
                    String temname = jsonObject.getString("Name");
                    temmap.put("First", jsonObject.getInt("First"));
                    temmap.put("Second", jsonObject.getInt("Second"));
                    temmap.put("Third", jsonObject.getInt("Third"));
                    Log.e("ERROR", temmap.get("First").toString());
                    cart_names1.put(temname, temmap);

                }
                strhold2.clear();
                strhold2.add("First");
                strhold2.add("Second");
                strhold2.add("Third");


                String[] strhold1 = new String[strhold2.size()];
                for (int i56 = 0; i56 < strhold2.size(); i56++) {
                    strhold1[i56] = strhold2.get(i56);
                }
                System.out.println(cart_names1);
                Log.e("ERROR", Integer.toString(cart_names1.size()) + "IN LATEST");
                if (cart_names1.size() > 1) {
                    System.out.println(cart_names1.size());
                    System.out.println(strhold2.size());
                    Combination.printCombination(cart_names1, strhold1, strhold2.size(), cart_names1.size(), 2);
                    ArrayList<String> wrong = Permutation.getlist();
                    System.out.println(wrong + "this is final");
                    setalldata(wrong);
                    System.out.println(wrong);
                    couldthis.clear();
                    couldthis.addAll(wrong);
                } else {
                    Single_Permutation.getpermute(cart_names1);
                    System.out.println(Single_Permutation.singlelist);
                    couldthis.clear();
                    couldthis.addAll(Single_Permutation.singlelist);
                    setalldata(Single_Permutation.singlelist);
                    Log.e("ERROR", "thisis the list 1" + getdataformap());
                }

            } catch (Exception e) {
                Log.e("ERROR", "Error pasting data " + e.toString());
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            /*SetMap setMap = new SetMap(getdataformap());
            setMap.execute();*/
            if (pd != null){ pd.dismiss();}
               ListFragment.addtolist(getdataformap());
                Log.e("ERROR", "This is putmap i" + getdataformap());
                SetMap setMap =new SetMap(getdataformap());
                setMap.execute();
            }
        }

    }

---

这意味着您正在修改集合，同时尝试对其进行迭代。它可能在同一个地方，也可能来自不同的线程。

对于每个循环，通常都是快速失败的，因此您无法更改集合（对于每个内部使用的迭代器）

而不是使用“for（Map.Entry>Entry:datapforput.entrySet（））”

创建一个迭代器，然后再次迭代映射，不要忘记指定 对新创建的entrySet的迭代器引用。只需在while/中每次为用于迭代的循环重新分配iterartor引用

---

}

我如何才能完成上述操作（请输入代码）？我对此很熟悉，但不知道它在我的代码中发生的位置，也不知道如何停止它查看您的代码，找到您在集合中迭代的位置，并查看您在这些集合中添加或删除内容的位置。然后寻找那些可能同时发生的地方。不幸的是，如果你从一开始就没有试着记住这一点，那么很难找到答案。我在很多地方迭代，但是在不同的集合上，这会导致问题吗？？？迭代不会导致问题。当您尝试从正在迭代的集合中添加和删除内容时，就会出现问题。也许可以改用哈希表。HashMap对于并发访问不安全。

public static class ListFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        public static ExpandableListView expandablelistview;
        public static CustomExpandableListAdapter expandableadapter;
        public static HashMap<Fitems, List<Fnitems>> datapforput = new HashMap<>();
        public static List<Fitems> mainforput = new ArrayList<>();
        public static View view;
        public static Context getha;

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            view = inflater.inflate(R.layout.activity_listfragment, container, false);
            //doddata();
            expandablelistview = (ExpandableListView) view.findViewById(R.id.expandableListView);
            expandableadapter = new CustomExpandableListAdapter(((Result) getActivity()).getha(), mainforput, datapforput);
            expandablelistview.setAdapter(expandableadapter);
            getha = ((Result) getActivity()).getha();
            return view;
        }

        @Override
        public void onStart() {
            super.onStart();
            Permutation.finallist = new ArrayList<>();
            Single_Permutation.singlelist = new ArrayList<>();
   /* doddata();
    expandablelistview = (ExpandableListView) view.findViewById(R.id.expandableListView);
    expandableadapter = new CustomExpandableListAdapter(((Result)getActivity()).getha(),mainforput,datapforput);
    expandablelistview.setAdapter(expandableadapter);*/
        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static void doddata() {
            Fitems fitems1 = new Fitems();
            Fitems fitems2 = new Fitems();
            Fnitems fnitems1 = new Fnitems();
            Fnitems fnitems2 = new Fnitems();
            Fnitems fnitems3 = new Fnitems();
            Fnitems fnitems4 = new Fnitems();
            fitems1.setName("AAA");
            fitems2.setName("BBB");
            fnitems1.setName("AAAa");
            fnitems2.setName("AAAb");
            fnitems3.setName("BBBa");
            fnitems4.setName("BBBb");
            List<Fnitems> listfnitem1 = new ArrayList<>();
            List<Fnitems> listfnitem2 = new ArrayList<>();
            listfnitem1.add(fnitems1);
            listfnitem1.add(fnitems2);
            listfnitem2.add(fnitems3);
            listfnitem2.add(fnitems4);
            datapforput.put(fitems1, listfnitem1);
            datapforput.put(fitems2, listfnitem2);
            mainforput.add(fitems1);
            mainforput.add(fitems2);
            //Log.e("ERROR", "thisis the list for god's sake " + Result.couldthis+datapforput.toString());
            if (Result.couldthis.size() > 0) {
                for (int i = 0; i < (Result.couldthis).size(); i++) {
                    for (Map.Entry<Fitems, List<Fnitems>> entry : datapforput.entrySet()) {
                        if (Result.couldthis.get(i).equals(entry.getKey().getName())){
                            Fnitems fnitems5 = new Fnitems();
                            fnitems5.setName(Search_multiple.cart_records.get(i).getName());
                            entry.getValue().add(fnitems5);
                        }else {
                            Fitems fitems3 = new Fitems();
                            fitems3.setName(Result.couldthis.get(i));
                            Fnitems fnitems5 = new Fnitems();
                            fnitems5.setName(Search_multiple.cart_records.get(i).getName());
                            List<Fnitems> listfnitem3 = new ArrayList<>();
                            listfnitem3.add(fnitems5);
                            datapforput.put(fitems3, listfnitem3);
                            mainforput.add(fitems3);
                        }
                    }
                }
            }
        }

        public static ListFragment newInstance() {
            ListFragment fragment = new ListFragment();
            Log.e("ERROR", "man .... " + fragment.getTag());
            return fragment;
        }

        public static void addtolist(ArrayList<String> dataforputting) {
           // Log.e("ERROR", "thisis the list 3" + (dataforputting));
            //if (expandableadapter != null){
            expandableadapter.clear();//}
            //Log.e("INFO", "This is mainforput" + mainforput + "This is dataforput" + datapforput);
            doddata();
            //Log.e("INFO", "This is mainforput" + mainforput + "This is dataforput" + datapforput);
            expandableadapter = new CustomExpandableListAdapter(getha, mainforput, datapforput);
            expandablelistview.setAdapter(expandableadapter);
        }


    }

07-13 18:16:11.955 17339-17339/nf.co.riaah.chutte E/ERROR: Inside populate Second
07-13 18:16:11.986 17339-17339/nf.co.riaah.chutte E/AndroidRuntime: FATAL EXCEPTION: main
                                                                    Process: nf.co.riaah.chutte, PID: 17339
                                                                    java.util.ConcurrentModificationException
                                                                        at java.util.HashMap$HashIterator.nextEntry(HashMap.java:787)
                                                                        at java.util.HashMap$EntryIterator.next(HashMap.java:824)
                                                                        at java.util.HashMap$EntryIterator.next(HashMap.java:822)
                                                                        at nf.co.riaah.chutte.Result$ListFragment.doddata(Result.java:199)
                                                                        at nf.co.riaah.chutte.Result$ListFragment.addtolist(Result.java:230)
                                                                        at nf.co.riaah.chutte.Result$SetMap.onPostExecute(Result.java:1049)
                                                                        at nf.co.riaah.chutte.Result$SetMap.onPostExecute(Result.java:967)
                                                                        at android.os.AsyncTask.finish(AsyncTask.java:636)
                                                                        at android.os.AsyncTask.access$500(AsyncTask.java:177)
                                                                        at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:653)
                                                                        at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                        at android.os.Looper.loop(Looper.java:139)
                                                                        at android.app.ActivityThread.main(ActivityThread.java:5298)
                                                                        at java.lang.reflect.Method.invoke(Native Method)
                                                                        at java.lang.reflect.Method.invoke(Method.java:372)
                                                                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:950)
                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:745)