片段内的 TabLayout 给出错误的项目视图

Question

我在 fragment 中使用 Tablayout 的项目中工作，我有三个选项卡，它们从网络服务中获取数据，应用程序的这一部分显示问题，我们有三个类别，一个是最近的，第二个是未回答的，第三个对于所有问题视图

这是我的情况，我的 Web 开发人员为我设计了 Web 服务 return 问题项，它们在 returned 项中共享相同的结构，但数据根据要求更改。

public class Questions_Fragment extends Fragment  {

    private TabLayout mTablayout;
    private ViewPager mViewpager;

    public static Questions_Fragment newInstance() {
        Questions_Fragment fragment = new Questions_Fragment();
        return fragment;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.questions_layout, null);
        mViewpager = (ViewPager) v.findViewById(R.id.viewPager);
        setupViewPager(mViewpager);

        mTablayout = (TabLayout) v.findViewById(R.id.tabs);
        mTablayout.setupWithViewPager(mViewpager);

        return v;
    }

    private void setupViewPager(ViewPager mViewpager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getChildFragmentManager());
        adapter.addFrag( QuestionsFragModel.newInstance(VolleyRequestHandler.RECENT_INT) , getResources().getString(R.string.newest));
        adapter.addFrag( QuestionsFragModel.newInstance(VolleyRequestHandler.UNANSWER_INT) , getResources().getString(R.string.notanswered));
        adapter.addFrag( QuestionsFragModel.newInstance(VolleyRequestHandler.ALLPOSTS_INT) , getResources().getString(R.string.allposts));
        mViewpager.setAdapter(adapter);
    }

我的视图寻呼机适配器 class 我扩展 FragmentStatePagerAdapter 每次用户打开选项卡时数据都会改变

public class ViewPagerAdapter extends FragmentStatePagerAdapter {
    private List<Fragment> mFragmentList = new ArrayList<>();
    private List<String> mFragmentTitleList=  new ArrayList<>();

    public ViewPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragmentList.get(position);
    }

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    public void addFrag(Fragment fra , String title){
        mFragmentList.add(fra);
        mFragmentTitleList.add(title);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }
}

但我看到它给我错误的看法，它显示有问题的图像没有图像，它给出了未回答问题的答案

抱歉我的问题很长，但我想知道我的代码有什么问题？？

我的列表适配器

public class ListViewAdapter extends RecyclerView.Adapter<ListViewAdapter.ViewHolder> {

    private Context _Context;

    private List<QuestionItem> Questions = new ArrayList<>();
    private API api;
    private int num;
    private int lastPosition = -1;
    public static final String BASE_POST_URl = "url....";


    public ListViewAdapter(Context context, List<QuestionItem> Questions) {
        this._Context = context;
        this.Questions = Questions;
        api = new API(context);
    }

    public ListViewAdapter(Context context, List<QuestionItem> Questions,
                           int num) {
        this._Context = context;
        this.Questions = Questions;
        this.num = num;
        api = new API(context);
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(_Context);
        View itemView = inflater.inflate(R.layout.question_row, parent, false);
        return new ViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, final int position) {
        Typeface tf = Typeface.createFromAsset(_Context.getAssets(),
                "fonts/GE_SS_Two_Bold.otf");
        Typeface tfreg = Typeface.createFromAsset(_Context.getAssets(),
                "fonts/GE_SS_Two_Light.otf");

        ImageLoader _ImageLoader = MySingleton.getInstance(_Context).getmImageLoader();

        if (Questions.get(position).user.userimageURL != null) {
            if (!Questions.get(position).user.getUserimageURL().isEmpty()) {
                //holder.userimageprog.setVisibility(View.VISIBLE);
                holder.imageView.setImageUrl(Profile_Fragment.BASE_URL + Questions.get(position).user.getUserimageURL(), _ImageLoader);
            }
        }

        if(Questions.get(position).Que_image_url != null){
            if (!Questions.get(position).getQue_image_url().isEmpty()) {
                holder._FrameLayout.setVisibility(View.VISIBLE);
                holder.post_img.setVisibility(View.VISIBLE);
                //holder.post_img_pro.setVisibility(View.VISIBLE);
                holder.post_img.setImageUrl(BASE_POST_URl + Questions.get(position).getQue_image_url(), _ImageLoader);
            }
        }

        holder.imageView.setDefaultImageResId(R.drawable.profile);
        holder.username.setTypeface(tf);
        holder.desc.setTypeface(tfreg);
        holder.Date.setTypeface(tfreg);
        holder.AnswersCount.setTypeface(tfreg);

        if(Questions.get(position).user.username != null){
            holder.username.setText(Questions.get(position).user.username);
        }
        if(Questions.get(position).Que_Content != null){
            holder.desc.setText(Questions.get(position).Que_Content);
        }
        if(Questions.get(position).category != null){
            holder.Category.setText(Questions.get(position).category);
        }

        if(Questions.get(position).Que_Date != null){
            holder.Date.setText(Questions.get(position).Que_Date);
        }

        if (!Questions.get(position).getComment().isEmpty()) {
            holder.arrow.setVisibility(View.VISIBLE);
            holder.AnswersCount.setVisibility(View.VISIBLE);
            holder.AnswersCount.setText(_Context.getResources().getString(R.string.youhaveanswer));
        }
        holder.arrow.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent (_Context , ViewAnswers.class);
                intent.putExtra("passedobject", (Parcelable) Questions.get(position));
                _Context.startActivity(intent);
            }
        });


//      Animation animation = null;
//       animation = AnimationUtils.loadAnimation(_Context,
//                 R.anim.up_from_bottom);
//       animation.setDuration(500);
//          view.setAnimation(animation);
//            animation = null;
//
//      Animation animation = AnimationUtils.loadAnimation(_Context,
//              (pos > lastPosition) ? R.anim.up_from_bottom
//                      : R.anim.down_from_top);
//      view.startAnimation(animation);
//      lastPosition = pos;

    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public int getItemCount() {
        return Questions.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {

        protected NetworkImageView imageView, post_img;
        protected TextView desc, Category, username, Date, AnswersCount;
        protected ProgressBar userimageprog, post_img_pro;
        protected ImageView arrow;
        protected FrameLayout _FrameLayout;

        public ViewHolder(View itemView) {
            super(itemView);
            imageView = (NetworkImageView) itemView.findViewById(R.id.ques_user_img);
            desc = (TextView) itemView.findViewById(R.id.ques_content);
            Category = (TextView) itemView.findViewById(R.id.category);
            post_img = (NetworkImageView) itemView.findViewById(R.id.post_img);
            userimageprog = (ProgressBar) itemView.findViewById(R.id.userimgae_prog);
            post_img_pro = (ProgressBar) itemView.findViewById(R.id.post_prog);
            username = (TextView) itemView.findViewById(R.id.username_ques);
            Date = (TextView) itemView.findViewById(R.id.date);
            AnswersCount = (TextView) itemView.findViewById(R.id.answers_con);
            arrow = (ImageView) itemView.findViewById(R.id.imageView1);
            _FrameLayout = (FrameLayout)itemView.findViewById(R.id.frameLayout2);

        }
    }
}

QuestionsFragModel 视图

public class QuestionsFragModel extends Fragment implements OnClickListener {

    private RecyclerView Ques_list;
    private ProgressBar list_prog;
    private ListViewAdapter adapter;
    private List<QuestionItem> Questions = new ArrayList<>();
    private TextView reload;
    private VolleyRequestHandler _VolleyRequestHandler;
    private int CONST_TYPE = 0;
    public static final String PASSED_INT = "passed_number";
    private CoordinatorLayout _coordiatelayout;


    static QuestionsFragModel newInstance(int type) {
        QuestionsFragModel f = new QuestionsFragModel();
        Bundle bundle = new Bundle();
        bundle.putInt(PASSED_INT , type);
        f.setArguments(bundle);
        return f;
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.question_layout, container, false);
        CONST_TYPE = getArguments() != null ? getArguments().getInt(PASSED_INT) : 7;
        _VolleyRequestHandler = new VolleyRequestHandler(getActivity());
        _coordiatelayout = (CoordinatorLayout) v.findViewById(R.id.coordiatelayout);

        Ques_list = (RecyclerView) v.findViewById(R.id.questionlist);
        Ques_list.setLayoutManager(new LinearLayoutManager(getActivity()));
        adapter = new ListViewAdapter(getActivity(), Questions);
        Ques_list.setAdapter(adapter);


        list_prog = (ProgressBar) v.findViewById(R.id.progressbar);
        reload = (TextView) v.findViewById(R.id.reload);

        getQuestationsPosts();

        reload.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View position) {
                getQuestationsPosts();
            }
        });

        final FloatingActionButton floatingView = (FloatingActionButton) v.findViewById(R.id.FloatingView);
        if (floatingView != null) {
            floatingView.setOnClickListener(this);
        }
        return v;
    }

    public void getQuestationsPosts() {
        API api = new API(getActivity());
        if (api.isNetworkConnected()) {
            list_prog.setVisibility(View.VISIBLE);
            reload.setVisibility(View.GONE);
            FetchQuestationsFromWeb();
        } else {
            Snackbar.make(_coordiatelayout, getResources().getString(R.string.nointernet), Snackbar.LENGTH_LONG).show();
            Ques_list.setVisibility(View.GONE);
            reload.setVisibility(View.VISIBLE);
        }
    }
    private void onSuccessResponse(Object response){
        list_prog.setVisibility(View.GONE);
        reload.setVisibility(View.GONE);
        Ques_list.setVisibility(View.VISIBLE);
        if(Questions != null){
            Questions.clear();
        }
        Questions = (List < QuestionItem>)  response;
        adapter = new ListViewAdapter(getActivity() ,Questions);
        Ques_list.setAdapter(adapter);
    }
    private void onErrorResponse(String error){
        list_prog.setVisibility(View.GONE);
        reload.setVisibility(View.VISIBLE);
        Snackbar.make(_coordiatelayout , error , Snackbar.LENGTH_LONG).show();
    }
    private void FetchQuestationsFromWeb() {

        _VolleyRequestHandler.HandleRequests(Request.Method.POST , CONST_TYPE, null, new VolleyResponseCallBack() {
            @Override
            public void RequestSuccess(Object response) {
                onSuccessResponse(response);
            }

            @Override
            public void RequestFailed(String error) {
                onErrorResponse(error);
            }
        });
    }

    @Override
    public void onClick(View arg0) {
        startActivity(new Intent(getActivity(), Add_Question.class));
    }


}

Answer 1

我不知道为什么你只有 3 个片段时使用 FragmentStatePagerAdapter 而不是 FragmentPagerAdapter。

AFAIK，如果您有大量片段，FragmentStatePagerAdapter 性能更好，因为它不会将整个片段存储在内存中。

无论如何，FragmentStatePagerAdapter 会在销毁片段时从 savedInstanceState 中保存片段的 Bundle。当用户返回时，新片段将使用片段的状态恢复。

所以你需要检查 savedInstanceState 之前:

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.question_layout, container, false);

        if (savedInstanceState!=null){
            // restore your state from "savedInstanceState"
        } else{
            CONST_TYPE = getArguments() != null ? getArguments().getInt(PASSED_INT) : 7;
        }
}

Answer 2

如果有人遇到问题，那是因为我在适配器中使用了 if 语句，只是你可以使用 if only 而没有 else

我使用的示例 if only

if (Questions.get(position).user.userimageURL != null) {
    if (!Questions.get(position).user.getUserimageURL().isEmpty()) {
        //holder.userimageprog.setVisibility(View.VISIBLE);
        holder.imageView.setImageUrl(Profile_Fragment.BASE_URL + Questions.get(position).user.getUserimageURL(), _ImageLoader);
    }
} else{
    // I should use else statement as well                  
}

片段内的 TabLayout 给出错误的项目视图

TabLayout inside fragment give wrong items view

android

android-fragments

android-tablayout