使用页面查看器创建页面的所有片段中都显示相同的数据

Question

我有一个在线数据库，其中我为每个页面存储了“标题”。 我正在使用异步任务从服务器下载数据，并且在日志语句中可以看到所有标题字符串都在正确检索。 使用FragmentStatePagerAdapter在MainActivity中创建页面。 我能够成功创建页面，但是我所有的页面都有相同的数据。

我的MainActivity.java：也有寻呼机适配器。

public class MainActivity extends AppCompatActivity {
    ViewPager viewPager=null;
    int numFrag1;
    String title = "", getTitle= "";


    public class TitleDownload extends AsyncTask<Void,Void,String>{

        @Override
        protected String doInBackground(Void... params) {

            CloudQuery query = new CloudQuery("CollegeFeeds");
            query.orderByAsc("updatedAt");
            query.include("imageTitle");

            try {
                query.count(new CloudIntegerCallback() {
                    @Override
                    public void done(Integer integer, CloudException e) throws CloudException {

                        if(integer != null){

                           //int numFrag = integer;
                            noofFrag(integer);
                            //Log.i("no of fragments", String.valueOf(integer));
                            System.out.println("in background"+ integer);
                        }
                    }
                });
            } catch (CloudException e) {
                e.printStackTrace();
            }

            try {
                query.find(new CloudObjectArrayCallback() {
                    @Override
                    public void done(CloudObject[] cloudObjects, CloudException e) throws CloudException {

                        if(cloudObjects != null){

                            //Log.i("no of fragments", String.valueOf(cloudObjects.length));

                            for (int i=0; i < cloudObjects.length; i++){

                               // Log.i("no of fragments", String.valueOf(cloudObjects.length));
                                title = cloudObjects[i].get("imageTitle").toString();
                                titleName(title);
                                Log.i("title", title);
                            }

                        }
                        if( e != null){
                            e.printStackTrace();
                        }

                    }
                });
            } catch (CloudException e) {
                e.printStackTrace();
            }

            return title ;
        }
    }
    public void noofFrag(int data){


         numFrag1 = data;

    }

    public void titleName(String titleData){

        getTitle = titleData;
        System.out.println("method title" + getTitle);

    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);


        CloudApp.init("qrhjtmypohec", "6e22fd4d-eef9-49b5-87a9-fba0f35075f9");

        new TitleDownload().execute();

        viewPager = (ViewPager) findViewById(R.id.pager);

        FragmentManager fragmentManager = getSupportFragmentManager();

        viewPager.setAdapter(new MyAdapter(fragmentManager));
        //viewPager.setPageTransformer(true, );


        //actionBar.setDisplayHomeAsUpEnabled(true);

    }

    class MyAdapter extends FragmentStatePagerAdapter {
        public MyAdapter(FragmentManager fm) {
            super(fm);
        }
        public int getItemPosition(Object object) {
            return POSITION_NONE;
        }

        @Override
        public Fragment getItem(int position) {

            AttendanceResultFeed fragment = null;

            for (int i=0; i<4; i++){

                if(position == i){

                    fragment = new AttendanceResultFeed(position);
                    fragment.getTag();
                    //System.out.println("fragment tag" + fragment.getTag());
                    //fragment.getNumber(i);
                    Bundle bundle = new Bundle();
                    bundle.putInt("number", i);
                    bundle.putString("title", getTitle);
                    fragment.setArguments(bundle);

                }
                //return fragment;
                new MyAdapter(getSupportFragmentManager()).notifyDataSetChanged();
            }
            return fragment;
        }

        @Override
        public int getCount() {
            // Log.d("info", "get count called");
            //numFrag1--;
            //Log.i("no of method(numFrag1) ", String.valueOf(numFrag1));
            new MyAdapter(getSupportFragmentManager()).notifyDataSetChanged();
            return 4;
        }



        @Override
        public CharSequence getPageTitle(int position) {

            if (position == 0){

                return "Attendance and Result";
            }

            if (position == 1){

                return "College Feeds";
            }

            if (position == 2){

                return "Branch Feeds";
            }
            return super.getPageTitle(position);
        }



    }

}

Fragment.java

public class AttendanceResultFeed extends Fragment {

    TextView textView, titleText;
    int number;
    String text= "";

    public AttendanceResultFeed(int position) {
        Log.i("position", String.valueOf(position));
    }


    public void getNumber (int data){

        number = data;
    }



    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if(savedInstanceState == null){
           // Log.d("info", "in attandec frag on create First time");
        }else {
           // Log.d("info", "in attandec frag on create subsequent time");
        }

    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.attendance_results_frag,container,false);

        textView = (TextView) rootView.findViewById(R.id.textView);
        titleText = (TextView )rootView.findViewById(R.id.titleText);


        number = getArguments().getInt("number",0);
        text = getArguments().getString("title");
        Log.d("info", String.valueOf(number));
        String num = String.valueOf(number);
        titleText.setText(text);
        textView.setText(num);

        return rootView;
    }

Answer 1

实际上，您在以下函数中使用相同的标题设置片段的参数：

        for (int i=0; i<4; i++){

            if(position == i){

                fragment = new AttendanceResultFeed(position);
                fragment.getTag();
                //System.out.println("fragment tag" + fragment.getTag());
                //fragment.getNumber(i);
                Bundle bundle = new Bundle();
                bundle.putInt("number", i);
                bundle.putString("title", getTitle);
                fragment.setArguments(bundle);

            }

如您所见，您将相同的getTitle放入fragments参数中，因此实际上所有片段均具有相同的标题。

我跟踪了您的代码，以了解getTitle获取位置，并且该赋值在titleName函数中，该函数也在另一个for循环中调用，因此基本上getTitle始终包含分配给它的最后一个String。

我不确定您的代码打算如何工作，但是这里有个提示：

使用ArrayList来保存标题：

//define this as a class member:
ArrayList<String> getTitle = new ArrayList<String>();

//change your titleName:
public void titleName(String titleData){

    getTitle.add(titleData);
    System.out.println("method title" + titleData);

}

//finally where you want to setArgument for your fragments use some logic to retrieve the titles, for example:
bundle.putString("title", getTitle.get(i));