使用SharedPreferences將數組從Api傳遞到另一個活動，並添加到已保存的數組

Question

簡介：我正在嘗試使用sharedpreferences將帶有子數組的數組傳遞到另一個活動中。

我想實現的目標 ：我有一個從api中獲得的數據數組，這些數據顯示為特定活動的列表。 這很好，因為它可以工作。

但是我希望在單擊項目時保存項目數據並加載到另一個活動中。 然后，在新活動上，我可以在關閉活動之前將新數據添加到已保存的信息中，然后再將數據保存回服務器上的數據庫中。

原因：我這樣做是因為網絡連接速度慢和頁面加載順暢。 我正在嘗試使用SharedPreferences在項目單擊時保存數組，將其加載到另一個活動中，然后將更多數據添加到SharedPreferences上已保存的數組中。

當前狀態：目前，我只能保存並獲取一個變量，而不是數組。

這是數組：

 {  "OutputCode":1,
"OutputMessage":"Success",
"OutputData":[
                {
                    "id":"1",
                    "status":"1",
                    "date_borrowed":"2018-01-16 16:34:01",
                    "date_returned":"0000-00-00 00:00:00",
                    "staff_id":"1",
                    "student_id": "1",
                    "log_contents":[{   "id":"8",
                                        "log_id":"1",
                                        "book_id":"1",
                                        "quantity":"3",
                                        "book_info":{   "id":"1",
                                                        "name":"Algebra",
                                                        "author":"John Smith",
                                                        "ISBN":"987-554-3243"}},
                                    {   "id": "5",
                                        "log_id": "1",
                                        "book_id": "1",
                                        "quantity": "2",
                                        "book_info": {  "id": "1",
                                                        "name": "C++",
                                                        "author": "Jane Smith",
                                                        "ISBN": "987-656-3870"}}],
                    "student_details":{"id":"1",
                                    "fname":"John",
                                    "lname":"James",
                                    "username":"username",
                                    "password":"password",
                                    "date_created":"2018-01-15 19:53:41",
                                    "phone":"+15673566"}
                },
                {
                    "id": "2",
                    "status": "0",
                    "date_borrowed": "2018-01-13 16:34:01",
                    "date_returned": "2018-01-14 17:10:14",
                    "staff_id": "1",
                    "student_id": "1",
                    "log_contents": [],
                    "student_details": {"id": "2",
                                        "fname": "Mary",
                                        "lname": "Jane",
                                        "username": "username",
                                        "password": "password",
                                        "date_created": "2018-01-15 20:53:41",
                                        "phone": "+14768986"}
                }]}

這是代碼

    access.runCommand("get_all_bookings", keys, values, new AtomAccess.Callback() {
        @Override
        public void onSuccess(JSONObject output) {
            try {
                String outputCode = output.getString("outputCode");
                String outputMessage = output.getString("outputMessage");

                updtedlist = (ListView) findViewById(R.id.lib_book_list_view);

                if (outputCode.equals("1")) {
                    JSONArray outputData = output.getJSONArray("outputData");
                    for (int i = 0; i < outputData.length(); i++) {
                        JSONObject obj = outputData.getJSONObject(i);
                        JSONObject stu = obj.getJSONObject("student_details");
                        Student bookBorrower = new Student(
                                stu.getString("id"),
                                stu.getString("fname"),
                                stu.getString("lname"),
                                stu.getString("username"),
                                stu.getString("password"),
                                stu.getString("date_created"),
                                stu.getString("phone"));
                        JSONArray cont = obj.getJSONArray("log_content");
                        ArrayList<Borrow> contents = new ArrayList<Borrow>();
                        for (int j = 0; j < cont.length(); j++) {
                            JSONObject con = cont.getJSONObject(j);
                            JSONObject buk = con.getJSONObject("book_info");
                            contents.add(new Borrow(
                                    con.getString("id"),
                                    con.getString("log_id"),
                                    con.getString("book_id"),
                                    con.getString("quantity"),
                                    new Book(buk.getString("id"),
                                            buk.getString("name"),
                                            buk.getString("author"),
                                            buk.getString("ISBN"))
                            ));

                        }

                        Log log = new Log(
                                obj.getString("id"),
                                obj.getString("status"),
                                obj.getString("date_borrowed"),
                                obj.getString("date_returned"),
                                obj.getString("staff_id"),
                                obj.getString("student_id"),
                                contents,
                                bookBorrower);

                        open_logs.add(log);

                    }
                }

                updtedlist.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                    @Override
                    public void onItemClick(AdapterView<?> adapterView, View view, int position, long offset) {

                        Log LogItem = (Log) adapter.getItem(position);

                        Student student = LogItem.getbookBorrower();
                        ArrayList<Borrow> buro = new ArrayList<Borrow>();
                        ArrayList<Book> buk = new ArrayList<Book>();
                        buro = LogItem.getContents();   //Here, am trying to get array of model 'Borrow' and 'Book'
                        Log.v("buro :", ""+buro); // the result here is [com.samuel.booking.entity.Product@e8f6200, com.samuel.booking.entity.Product@aad103]

                        SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(context);
                        SharedPreferences.Editor editor = settings.edit();
                        editor.putString("fang", ""+student.getFirstName()); // This return the right info
                        editor.putString("lang", ""+buro);  // This yields no result except that in the log above
                        editor.apply();

                        //I was able to get the variable below
                        Intent i =  new Intent(LogsActivity.this, LogInfoActivity.class);
                        // i.putExtra("KEY_log_ID", LogItem.getId());
                        // i.putExtra("KEY_Log_STATUS", LogItem.getStatus());
                        // i.putExtra("KEY_Los_Student_ID", student.getId());
                        // i.putExtra("KEY_Log_Student_FNAME", student.getFirstName())
                        startActivity(i);

                    }

                });

                adapter = new LogsAdapter(LogsActivity.this, open_Logs);
                updtedlist.setAdapter(adapter);
                removeLoadingOverlay();
            } catch (JSONException e) {

            }
        }
    });

我很樂意采用更好的方法來實現這一目標。 我只是想避免一直從Api加載數據。

Answer 1

做一個OutputData對象，並使其Parcelable ，然后使用Intent.putExtra()而開始另一個Activity 。 這是將對象從Activity傳遞到Activity的正確方法，您不應使用SharedPreferences 。 查看此鏈接 。