Java 是否对不同的片段使用viewpager？

我最近开始写一个应用程序，让我从论坛上获取信息。我使用JSoup库来抓取数据。我的第一部分进展顺利

当应用程序打开时，它只是从sitesub论坛名称获取数据并传递，以便listview能够显示它们。当我在listview中按下一个项目时，它只会在子论坛中获得线程列表。除了listview没有正确更新之外，所有的东西都正常工作

正如您所看到的，当我按下列表中的一个项目时，它只是列表中的第一个项目，然后将loadedSub设置为true，然后使用异步任务获取线程列表，然后在postexecute中调用notifyDataSetChanged on PagerAdapter。问题是它只是完美地更新了UI，甚至只留下我想要的1个选项卡，但问题是threadList没有出现在listview中。它只显示包含以前数据的listview，而不是threadlist

我应该使用另一项活动还是缺少什么

MainActivity.java

ForumListAdapter.java

---

好的，我用FragmentStatePageAdapter而不是FragmentPageAdapter解决了这个问题

package com.ovnis.sscattered.elakiriunofficial;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.support.design.widget.TabLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;

import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;

import org.jsoup.Connection;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {

    /**
     * The {@link android.support.v4.view.PagerAdapter} that will provide
     * fragments for each of the sections. We use a
     * {@link FragmentPagerAdapter} derivative, which will keep every
     * loaded fragment in memory. If this becomes too memory intensive, it
     * may be best to switch to a
     * {@link android.support.v4.app.FragmentStatePagerAdapter}.
     */
    public static SectionsPagerAdapter mSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will host the section contents.
     */
    public static ViewPager mViewPager;

    public static String[][] forumListSubForumsList = new String[13][];
    public static String[][] forumListSubForumListLinks = new String[13][];

    public static String[][] threadListLinks = new String[2][];

    static Context context;

    public String[] forumNumbers = {"1", "86", "89", "6",
                                    "66", "79", "70", "12",
                                    "16", "33", "42", "25",
                                    "22"};

    public static String subforumLink;

    static boolean loaded = false;
    static boolean loadedSub = false;

    static boolean subForumMode = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        // Create the adapter that will return a fragment for each of the three
        // primary sections of the activity.
        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

        // Set up the ViewPager with the sections adapter.
        mViewPager = (ViewPager) findViewById(R.id.container);
        mViewPager.setAdapter(mSectionsPagerAdapter);



        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
        tabLayout.setupWithViewPager(mViewPager);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        new GetSubForumList().execute();

        context = getBaseContext();
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class SubForumsFrag extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */

        static ListView listview;
        static ForumListAdapter adapter;

        int pos = 0;

        public SubForumsFrag() {

        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static SubForumsFrag newInstance(int pos) {
            SubForumsFrag fragment = new SubForumsFrag();
            Bundle args = new Bundle();
            args.putInt("poskey", pos);
            fragment.setArguments(args);
            return fragment;
        }

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

            View rootView = inflater.inflate(R.layout.list_base, container, false);
            listview = (ListView) rootView.findViewById(R.id.listview);

            pos = getArguments().getInt("poskey");

            if(loaded){
                adapter = new ForumListAdapter(getActivity(), forumListSubForumsList[pos]);
            }
            listview.setAdapter(adapter);

            listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    Toast.makeText(getContext(), forumListSubForumListLinks[pos][position], Toast.LENGTH_SHORT).show();
                    subForumMode = true;
                    subforumLink = forumListSubForumListLinks[pos][position];
                    new GetThreadList().execute();
                }
            });

            return rootView;
        }
    }

    public static class ThreadListFrag extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */

        static ListView listview;
        static ForumListAdapter adapter;

        int pos = 0;

        public ThreadListFrag() {

        }

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static ThreadListFrag newInstance() {
            ThreadListFrag fragment = new ThreadListFrag();
            return fragment;
        }

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

            View rootView = inflater.inflate(R.layout.list_base, container, false);
            listview = (ListView) rootView.findViewById(R.id.listview);

            if(loadedSub){
                adapter = new ForumListAdapter(getActivity(), threadListLinks[0]);
            }
            listview.setAdapter(adapter);

            listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    //Toast.makeText(getContext(), forumListSubForumListLinks[pos][position], Toast.LENGTH_SHORT).show();
                }
            });

            return rootView;
        }
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
     * one of the sections/tabs/pages.
     */
    public class SectionsPagerAdapter extends FragmentPagerAdapter {

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

        @Override
        public Fragment getItem(int position) {
            // getItem is called to instantiate the fragment for the given page.
            // Return a SubForumsFrag (defined as a static inner class below).

            if(!subForumMode){
                return SubForumsFrag.newInstance(position);
            }else{
                return ThreadListFrag.newInstance();
            }
        }

        @Override
        public int getCount() {
            // Show 13 total pages.

            if(!subForumMode){
                return 13;
            }else{
                return 1;
            }
        }

        @Override
        public CharSequence getPageTitle(int position) {
            if(!subForumMode){
                switch (position) {
                    case 0:
                        return "Elakiri";
                    case 1:
                        return "Cooking";
                    case 2:
                        return "B & M";
                    case 3:
                        return "General";
                    case 4:
                        return "E. Traveler";
                    case 5:
                        return "Automobile";
                    case 6:
                        return "Motorcycles";
                    case 7:
                        return "Entertainment";
                    case 8:
                        return "C & I";
                    case 9:
                        return "S. Piyasa";
                    case 10:
                        return "Elakiri Magic";
                    case 11:
                        return "Games";
                    case 12:
                        return "Mobile";
                }
            }else{
                return "Bitch Me";
            }
            return null;
        }

        @Override
        public int getItemPosition(Object obj){
            return POSITION_NONE;
        }
    }

    class GetSubForumList extends AsyncTask<Void, Integer, String>
    {
        String TAG = getClass().getSimpleName();

        ProgressDialog dialog;

        protected void onPreExecute (){
            Log.d(TAG + " PreExceute","On pre Exceute......");

            dialog = new ProgressDialog(MainActivity.this);
            dialog.setTitle("Loading...");
            dialog.setIndeterminate(true);
            dialog.setCancelable(false);
            dialog.show();
        }

        protected String doInBackground(Void...arg0){
            Log.d(TAG + " DoINBackGround","On doInBackground...");

            try {
                Connection.Response response = Jsoup.connect("http://www.elakiri.com/forum/")
                        .execute();

                Document parsedDoc = response.parse();

                Element doc;
                Elements doce;

                for(int i = 0; i < forumNumbers.length; i++){
                    doc = parsedDoc.select("tbody#collapseobj_forumbit_" + forumNumbers[i]).first();
                    doce = doc.select("a[href] strong");
                    forumListSubForumsList[i] = new String[(doce.size()+1)/2];
                    forumListSubForumListLinks[i] = new String[(doce.size()+1)/2];
                    for(int q = 0; q < (doce.size()+1)/2; q++){
                        forumListSubForumsList[i][q] = doce.get(q*2).text();
                        forumListSubForumListLinks[i][q] = doce.get(q*2).parent().absUrl("href");
                    }
                }

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

            return "Shot";
        }

        protected void onProgressUpdate(Integer...a){
            Log.d(TAG + " onProgressUpdate", "You are in progress update ... " + a[0]);

        }

        protected void onPostExecute(String result) {
            Log.d(TAG + " onPostExecute", "" + result);

            loaded = true;
            mViewPager.invalidate();
            mSectionsPagerAdapter.notifyDataSetChanged();

            dialog.dismiss();
        }
    }

    static class GetThreadList extends AsyncTask<Void, Integer, String>
    {
        String TAG = getClass().getSimpleName();

        ProgressDialog dialog;

        protected void onPreExecute (){
            Log.d(TAG + " PreExceute","On pre Exceute......");

            dialog = new ProgressDialog(context);
            dialog.setTitle("Loading...");
            dialog.setIndeterminate(true);
            dialog.setCancelable(false);
//            dialog.show();
        }

        protected String doInBackground(Void...arg0){
            Log.d(TAG + " DoINBackGround","On doInBackground...");

            try {
                Connection.Response response = Jsoup.connect(subforumLink)
                        .execute();

                Element doc = response.parse().select("tbody#threadbits_forum_2").first();

                Elements doce = doc.select("a[id^=thread_title_]");

                threadListLinks[0] = new String[doce.size()];
                threadListLinks[1] = new String[doce.size()];

                for(int i = 0; i < doce.size(); i++){
                    threadListLinks[0][i] = doce.get(i).text();
                    threadListLinks[1][i] = doce.get(i).absUrl("href");
                }

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

            return "Shot";
        }

        protected void onProgressUpdate(Integer...a){
            Log.d(TAG + " onProgressUpdate", "You are in progress update ... " + a[0]);

        }

        protected void onPostExecute(String result) {
            Log.d(TAG + " onPostExecute", "" + result);

            loadedSub = true;
            mViewPager.invalidate();
            mSectionsPagerAdapter.notifyDataSetChanged();
        }
    }
}

public class ForumListAdapter extends ArrayAdapter<String> {
    private final Context context;
    private final String[] values;

    public ForumListAdapter(Context context, String[] values) {
        super(context, R.layout.main_adapter ,values);
        this.context = context;
        this.values = values;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View rowView = inflater.inflate(R.layout.main_adapter, parent, false);
        TextView textView = (TextView) rowView.findViewById(R.id.firstLine);
        textView.setText(values[position]);

        return rowView;
    }
}