安卓 : Custom ListView Disappear After Orientation Change

Question

问题

我创建了自定义 ListView，其中包含自定义 View ，以及每个列表项的一些 TextView 。一切都按我的预期工作，直到设备方向改变，ListView 消失。我知道当方向改变 Activity 重新发生时会发生问题。但是，我已经在应用程序中将必要的文件保存为 JSON 字符串格式，当 Activity 重新创建时，我发现数据已加载并成功运行，直到代码结束没有强制关闭但是，listview 没有显示？

注意

我确信我的保存数据是可用的，因为这个文件用于防止从互联网上获取数据(如果可用的话)，我已经测试过了，它可以工作!

我的自定义 ListView 有 ListView 类提供数组列表和适配器类，但我不能在这里提供，因为它太长了。

主类

   @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.schedule);

        aq = new AQuery(this);
        lvSchedule = (ListView) findViewById(R.id.listView_schedule);
        scheduleLvItems = new ArrayList<Schedule_ListView>();
        dm = new DataManager(this);


        //check available in app data
        String scheduleJSON = dm.readFile("scheduleJSON");
        if (scheduleJSON != "empty"){
            System.out.println(scheduleJSON);
            renderData(scheduleJSON);
        }
        else{
            String url = "http://requestURL/getSchedule_v2.php?+" +
                    "loginId="+yourID+
                    "&password="+yourPassword+
                    "&year=2013&semester=2";

            aq.ajax(url,String.class, this,"cb1");
        }

    }


    public void cb1(String url, String html, AjaxStatus status){

        System.out.println(html);
        renderData(html);

    }

    public void renderData(String jsonString){

        try {

            List<List<String>> monData = new ArrayList<List<String>>();
            List<List<String>> tueData = new ArrayList<List<String>>();
            List<List<String>> wedData = new ArrayList<List<String>>();
            List<List<String>> thuData = new ArrayList<List<String>>();
            List<List<String>> friData = new ArrayList<List<String>>();
            List<List<String>> satData = new ArrayList<List<String>>();
            List<List<String>> sunData = new ArrayList<List<String>>();

                        /*Note [Knowledge]
                        *JSON Symbol {,} = JSONObject
                        *JSON symbol [,] = JSONArray
                        */

            //Change JSONString to JSONArray
            JSONArray jsonArray_data = new JSONArray(jsonString);

            //Set jsonArray_data in global variable for further use
//            ((Global_Variable)getApplicationContext()).setJsonSubject(jsonArray_data);

            //Save Persistence Json Array in app data for fetch with out internet
            dm.writeFile("scheduleJSON",jsonArray_data.toString());

            for(int i = 0; i < jsonArray_data.length(); i++){
                //Change object to String and stored each JSON item in Variable
                JSONObject dataRecord = jsonArray_data.getJSONObject(i);

                String      yearSemester    = dataRecord.getString("YEAR / SEM");
                String      courseID        = dataRecord.getString("COURSE ID");
                String      courseName      = dataRecord.getString("COURSE NAME");
                String      courseSection   = dataRecord.getString("SECTION");
                JSONArray   courseInfo      = dataRecord.getJSONArray("COURSE INFO");
                String      finalDate       = dataRecord.getString("FINAL DATE");
                String      finalRoom       = dataRecord.getString("FINAL ROOM");
                String      finalTime       = dataRecord.getString("FINAL TIME");
                String      midtermDate     = dataRecord.getString("MIDTERM DATE");
                String      midtermRoom     = dataRecord.getString("MIDTERM ROOM");
                String      midtermTime     = dataRecord.getString("MIDTERM TIME");
                int         subjectColor    = getResources().getColor(SUBJECT_COLOR[i]);

                for(int ii = 0; ii < courseInfo.length(); ii++){
                    //Change object to String and stored each JSON item in Variable
                    JSONObject infoRecord = courseInfo.getJSONObject(ii);

                    String day          =   infoRecord.getString("DAY").replace(".","").trim();
                    String tStart       =   infoRecord.getString("TIME").replace(" - ","").trim().substring(0,5);
                    String tStop        =   infoRecord.getString("TIME").replace(" - ","").trim().substring(5);
                    String roomStudy    =   infoRecord.getString("ROOM STUDY");
                    String instructor   =   infoRecord.getString("INSTRUCTOR");

                    List<String> dataRow = new ArrayList<String>();

                    if (day.contains("Mon")) {
                        dataRow.add(courseName);                    //course name
                        dataRow.add(tStart);                        //period start
                        dataRow.add(tStop);                         //period end
                        dataRow.add(String.valueOf(subjectColor));  //subject color
                        dataRow.add(String.valueOf(i));             //subject position in json
                        monData.add(dataRow);
                    } else if (day.contains("Tue")) {
                        dataRow.add(courseName);                    //course name
                        dataRow.add(tStart);                        //period start
                        dataRow.add(tStop);                         //period end
                        dataRow.add(String.valueOf(subjectColor));  //subject color
                        dataRow.add(String.valueOf(i));             //subject position in json
                        tueData.add(dataRow);
                    } else if (day.contains("Wed")) {
                        dataRow.add(courseName);                    //course name
                        dataRow.add(tStart);                        //period start
                        dataRow.add(tStop);                         //period end
                        dataRow.add(String.valueOf(subjectColor));  //subject color
                        dataRow.add(String.valueOf(i));             //subject position in json
                        wedData.add(dataRow);
                    } else if (day.contains("Thu")) {
                        dataRow.add(courseName);                    //course name
                        dataRow.add(tStart);                        //period start
                        dataRow.add(tStop);                         //period end
                        dataRow.add(String.valueOf(subjectColor));  //subject color
                        dataRow.add(String.valueOf(i));             //subject position in json
                        thuData.add(dataRow);
                    } else if (day.contains("Fri")) {
                        dataRow.add(courseName);                    //course name
                        dataRow.add(tStart);                        //period start
                        dataRow.add(tStop);                         //period end
                        dataRow.add(String.valueOf(subjectColor));  //subject color
                        dataRow.add(String.valueOf(i));             //subject position in json
                        friData.add(dataRow);
                    } else if (day.contains("Sat")) {
                        dataRow.add(courseName);                    //course name
                        dataRow.add(tStart);                        //period start
                        dataRow.add(tStop);                         //period end
                        dataRow.add(String.valueOf(subjectColor));  //subject color
                        dataRow.add(String.valueOf(i));             //subject position in json
                        satData.add(dataRow);
                    } else if (day.contains("Sun")){
                        dataRow.add(courseName);                    //course name
                        dataRow.add(tStart);                        //period start
                        dataRow.add(tStop);                         //period end
                        dataRow.add(String.valueOf(subjectColor));  //subject color
                        dataRow.add(String.valueOf(i));             //subject position in json
                        sunData.add(dataRow);
                    }
                }
            }

            if(monData.size() != 0){
                scheduleLvItems.add(new Schedule_ListView(
                        R.drawable.monday_mdpi,
                        monData,
                        getResources().getInteger(R.integer.COLLAPSED_HEIGHT_1)
                ));
            }
            if(tueData.size() != 0){
                scheduleLvItems.add(new Schedule_ListView(
                        R.drawable.tuesday_mdpi,
                        tueData,
                        getResources().getInteger(R.integer.COLLAPSED_HEIGHT_1)
                ));
            }
            if(wedData.size() != 0){
                scheduleLvItems.add(new Schedule_ListView(
                        R.drawable.wendesday_mdpi,
                        wedData,
                        getResources().getInteger(R.integer.COLLAPSED_HEIGHT_1)
                ));
            }
            if(thuData.size() != 0){
                scheduleLvItems.add(new Schedule_ListView(
                        R.drawable.thursday_mdpi,
                        thuData,
                        getResources().getInteger(R.integer.COLLAPSED_HEIGHT_1)
                ));
            }
            if(friData.size() != 0){
                scheduleLvItems.add(new Schedule_ListView(
                        R.drawable.friday_mdpi,
                        friData,
                        getResources().getInteger(R.integer.COLLAPSED_HEIGHT_1)
                ));
            }
            if(satData.size() != 0){
                scheduleLvItems.add(new Schedule_ListView(
                        R.drawable.saturday_mdpi,
                        satData,
                        getResources().getInteger(R.integer.COLLAPSED_HEIGHT_1)
                ));
            }
            if(sunData.size() != 0) {
                scheduleLvItems.add(new Schedule_ListView(
                        R.drawable.sunday_mdpi,
                        sunData,
                        getResources().getInteger(R.integer.COLLAPSED_HEIGHT_1)
                ));
            }

            //add padding top - bottom for listview
            LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            LinearLayout header = (LinearLayout) inflater.inflate(R.layout.listview_header, null);
            lvSchedule.addFooterView(header, null, false);
            lvSchedule.addHeaderView(header, null, false);
            //setup listView Adapter
            scheduleAdapter = new Schedule_Adapter(Schedule.this, R.layout.schedule_listview, scheduleLvItems);
            //setup adapter to listView
            lvSchedule.setAdapter(scheduleAdapter);
            //setup OnClickListener
            lvSchedule.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {

                    int postion = i - lvSchedule.getHeaderViewsCount();
                    toggle(view, postion);
                }
            });

        }catch (Exception e){
            System.out.println(e);
        }
    }

Answer 1

发生这种情况是因为您在 onCreate 中将数据分发到 ListView 并且每当您更改方向时， Activity 将重新启动并且不会调用 onCreate。因此，它不会被分发。要解决此问题，只需将此行和相关行移动到 onResume

renderData(scheduleJSON); //take more important lines with it to onResume

应该是这样的:

protected void onResume()
{
   super.onResume();
   renderData(scheduleJSON); //take more important lines with it to onResume
}

第二种解决方案:

您可以通过将其添加到 Activity 标签中的 list 中来防止方向发生变化时 Activity 重新启动

<activity android:name="YourActivity"
 android:screenOrientation="portrait"
 android:configChanges="keyboardHidden|orientation"> //this line