Question

我的ViewPager片段中存在问题当我从导航视图中打开片段时，我的“ListView”仅在我有一个标签时起作用当我放置2个或更多选项卡时，错误的列表视图仅出现在第二个选项卡中。

这是我的片段ViewPager：

public class JournaFragment extends Fragment{

private SlidingTabLayout mSlidingTabLayout;
private ViewPager mViewPager;

JournalDate journalDate;
ArrayList<JournalDate> monthArray ;
JournalSwipeAdapter monthAdapter;

public JournaFragment(){}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_journal, null);

    mViewPager = (ViewPager) v.findViewById(R.id.viewpager);
    journalDate = new JournalDate();
    monthArray = journalDate.getMounthForTable();
    monthAdapter = new JournalSwipeAdapter(ParentActivity.getContext(),monthArray);
    mViewPager.setAdapter(monthAdapter);



    mSlidingTabLayout = (SlidingTabLayout) v.findViewById(R.id.sliding_tabs);
    mSlidingTabLayout.setViewPager(mViewPager);

    //System.out.println(" CurrentItem :" + mViewPager.getCurrentItem());
    monthAdapter.getLessonsForJournal(mViewPager.getCurrentItem());

    monthAdapter.notifyDataSetChanged();

    return v;
}




@Override
public void onViewCreated(View view, Bundle savedInstanceState) {

}

和适配器扩展PagerAdapter：

public class JournalSwipeAdapter extends PagerAdapter {

private Context ctx;
private LayoutInflater layoutInflater;
ArrayList<JournalDate> arrayList;

ProgressBar pg;
TextView title;
TextView noJournal;
TextView indexPage;

ListView dayListView;
ArrayList<JournalFragmentDayItem> dayItemArrayList;
JournalFragmentDayItem dayItem;
JournalFragmentDayAdapter dayAdapter;

public JournalSwipeAdapter(Context ctx, ArrayList<JournalDate> arrayList) {
    this.ctx = ctx;
    this.arrayList = arrayList;
}

@Override
public int getCount() {
    if (arrayList == null) {
        return 0;

    } else
        return arrayList.size();

}

@Override
public boolean isViewFromObject(View view, Object o) {
    return o == view;
}


public JournalDate getItem(int position) {
    return arrayList.get(position);
}

@Override
public int getItemPosition(Object object) {
    return super.getItemPosition(object);
}

@Override
public CharSequence getPageTitle(int position) {
    switch (arrayList.get(position).calendar) {
        case (0):
            arrayList.get(position).month = "Январь";
            break;
        case (1):
            arrayList.get(position).month = "Февраль";
            break;
        case (2):
            arrayList.get(position).month = "Март";
            break;
        case (3):
            arrayList.get(position).month = "Апрель";
            break;
        case (4):
            arrayList.get(position).month = "Май";
            break;
        case (5):
            arrayList.get(position).month = "Июнь";
            break;
        case (6):
            arrayList.get(position).month = "Июль";
            break;
        case (7):
            arrayList.get(position).month = "Август";
            break;
        case (8):
            arrayList.get(position).month = "Сентябрь";
            break;
        case (9):
            arrayList.get(position).month = "Октябрь";
            break;
        case (10):
            arrayList.get(position).month = "Ноябрь";
            break;
        case (11):
            arrayList.get(position).month = "Декабрь";
            break;
    }
    return arrayList.get(position).month;
}

@Override
public Object instantiateItem(ViewGroup container, int position) {
    // Inflate a new layout from our resources
    layoutInflater = (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View view = layoutInflater.inflate(R.layout.fragment_jourlan_swipe_layout, container, false);
    // Add the newly created View to the ViewPager
    container.addView(view);

    // Retrieve a TextView from the inflated View, and update it's text
    title = (TextView) view.findViewById(R.id.item_title);
    pg = (ProgressBar) view.findViewById(R.id.progressBar);
    dayListView = (ListView) view.findViewById(R.id.fragment_journal_swipe_list);
    noJournal = (TextView)view.findViewById(R.id.fragment_journal_swipe_nojournal);
    indexPage = (TextView)view.findViewById(R.id.item_title);
    view.setTag("myView"+position);
    noJournal.setVisibility(View.GONE);

    // Return the View
    return view;
}


public void getLessonsForJournal(final int position) {
    HtmlRequest htmlRequest;
    RequestQueue requestQueue;
   // System.out.println(" Position: "+ position);
    Map<String, String> params = new HashMap<>();
    params.put("studentId", "5");
    params.put("year", String.valueOf(arrayList.get(position).year));
    params.put("mounth", String.valueOf(arrayList.get(position).calendar + 1));

    htmlRequest = new HtmlRequest(Request.Method.POST, Links.getJournalLessons, params, "UTF-8",
            new Response.Listener<String>() {

                @Override
                public void onResponse(String response) {

                   // System.out.println(" " +response);
                    if (response.equals("false")) {
                       // System.out.println("Failed Lessons ");

                    } else {

                        arrayList.get(position).responseForLessons = response;
                        notifyDataSetChanged();

                        dayItem = new JournalFragmentDayItem();
                        dayItemArrayList = dayItem.getDayArray(arrayList.get(position).responseForLessons);
                        dayAdapter = new JournalFragmentDayAdapter(ParentActivity.getContext(), dayItemArrayList);
                        dayListView.setAdapter(dayAdapter);

                        pg.setVisibility(View.GONE);
                        dayListView.setVisibility(View.VISIBLE);
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Log.e("eror", error.getMessage() + "");
                    Toast.makeText(ParentActivity.getContext(), "" + error.getMessage(), Toast.LENGTH_LONG).show();
                }
            });

    htmlRequest.setTag("TAG");
    requestQueue = Volley.newRequestQueue(ParentActivity.getContext());
    requestQueue.add(htmlRequest);


}


/**
 * Destroy the item from the ViewPager. In our case this is simply
 * removing the View.
 */
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    container.removeView((View) object);
}
}

Answer 1

原因是在ViewPagerAdapter内部，您对每个页面使用相同的元素（ListView等等）。这样只显示最后一个实例化的页面。

尽量不要在函数public Object instantiateItem(ViewGroup container, int position)中重用它们，并在方法中创建它们。

修改

帮助您了解应该做出哪些更改的指南：

您更新的课程字段：

private Context ctx; private LayoutInflater layoutInflater; ArrayList<JournalDate> arrayList; ArrayList<JournalFragmentDayItem> dayItemArrayList; JournalFragmentDayItem dayItem; JournalFragmentDayAdapter dayAdapter;

更新方法public Object instantiateItem(ViewGroup container, int position)：

@Override public Object instantiateItem(ViewGroup container, int position) { // Inflate a new layout from our resources layoutInflater = (LayoutInflater) ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE); View view = layoutInflater.inflate(R.layout.fragment_jourlan_swipe_layout, container, false); // Add the newly created View to the ViewPager container.addView(view); // Retrieve a TextView from the inflated View, and update it's text TextView title = (TextView) view.findViewById(R.id.item_title); ProgressBar pg = (ProgressBar) view.findViewById(R.id.progressBar); ListView dayListView = (ListView) view.findViewById(R.id.fragment_journal_swipe_list); TextView noJournal = (TextView) view.findViewById(R.id.fragment_journal_swipe_nojournal); TextView indexPage = (TextView) view.findViewById(R.id.item_title); view.setTag("myView" + position); noJournal.setVisibility(View.GONE); // Return the View return view; }

ViewPager不能与ListView一起使用corectry

1 个答案: