使用ASyncTask时，java数组未显示在ArrayAdapter中

Question

我正在使用Jsoup从我的网站上获取歌曲名称作为字符串。我希望这些歌曲以ArrayAdapter格式播放。歌曲存储在ArrayList数据类型中，ArrayAdapter需要该数据类型作为参数。歌曲名称都是使用Jsoup正确获取的，但是显示存储歌曲名称的ArrayList内容的代码不会相应地更新UI

import 安卓.os.AsyncTask;
import 安卓.os.Bundle;
import 安卓.os.Handler;
import 安卓.util.Log;
import 安卓.view.MenuItem;
import 安卓.view.View;
import 安卓.widget.ArrayAdapter;
import 安卓.widget.PopupMenu;
import 安卓.widget.TextView;
import 安卓.widget.Toast;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

import com.lorentzos.flingswipe.SwipeFlingAdapterView;

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.select.Elements;
public class AppHome extends AppCompatActivity implements PopupMenu.OnMenuItemClickListener {
    TextView texx;
    ArrayList<String> aList = new ArrayList<>();
    private ArrayAdapter<String> arrayAdapter;
    private int i;

    AsyncTask<?,?,?> runningTask;

    String[] attributeList = {"song1", "song2", "song3", "song4", "song5", "song6", "song7", "song8", "song9", "song10", "song11", "song12", "song13", "song14", "song15", "song16", "song17", "song18", "song19", "song20", "song21", "song22", "song23", "song24", "song25", "song26", "song27", "song28", "song29", "song30", "song31", "song32", "song33", "song34", "song35", "song36", "song37", "song38", "song39", "song40"};
    String[] obtainedSongNamesFromAsyncTask = new String[40];

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_app_home);
        texx = findViewById(R.id.text1);

        runningTask = new doit();
        runningTask.execute();

    }


    private final class doit extends AsyncTask<Object, Void, String>
    {
        @Override
        protected String doInBackground(Object... params)
        {
            try
            {
                Document doc = Jsoup.connect("https://screenscrape4top40.000webhostapp.com/").userAgent("Mozilla/(Windows NT 6.1)").get();
//                Elements firstSong = doc.select("a[id=song1]");
//                String firstSongString = firstSong.text();
//                Log.d("jsoupTag", firstSongString);
                // TODO 1. loop through every element in array
                // TODO 2. Create new string by concatenating the .select() contents (pre & post)
                // TODO 3. Add to wrapper class array
                for (int i = 0; i != attributeList.length; i++)
                {
                    String s = "a[id=" + attributeList[i] + "]";
                    Elements currentSong = doc.select(s);
                    String currentSongTextOnly = currentSong.text();
                    aList.add(currentSongTextOnly);
                }
                Log.d("jsoupTag", Arrays.toString(aList.toArray()));
                // Outputs: [ROSES, BLINDING LIGHTS, THE BOX, LONELY, PHYSICAL, DON'T START NOW, SAY SO, RAIN, INTENTIONS, GODZILLA, BOYFRIEND, NO TIME TO DIE, ADORE YOU, DANCE MONKEY, BETTER OFF WITHOUT YOU, YOU SHOULD BE SAD, IN YOUR EYES, STUPID LOVE, DEATH BED, FALLING, SUPALONELY, BLUEBERRY FAYGO, AFTER HOURS, TO DIE FOR, BEFORE YOU GO, CITY OF ANGELS, WHAT A MAN GOTTA DO, KNOW YOUR WORTH, OWN IT, SOMEONE YOU LOVED, TEQUILA, BOSS BITCH, NO JUDGEMENT, FLOWERS, BIRTHDAY, SUNDAY BEST, SCORPION, THE TAKE, WAR, PLAY PLAY]
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
            return "Executed";
        }

        @Override
        public void onPostExecute(String result)
        {
            arrayAdapter = new ArrayAdapter<>(AppHome.this, R.layout.item, R.id.helloText, aList);

            SwipeFlingAdapterView flingContainer = findViewById(R.id.frame);


            registerForContextMenu(flingContainer);


            flingContainer.setAdapter(arrayAdapter);

            flingContainer.setFlingListener(new SwipeFlingAdapterView.onFlingListener() {
                @Override
                public void removeFirstObjectInAdapter() {
                    // this is the simplest way to delete an object from the Adapter (/AdapterView)
                    Log.d("LIST", "removed object!");
                    aList.remove(0);
                    arrayAdapter.notifyDataSetChanged();
                }

                @Override
                public void onLeftCardExit(Object dataObject) {
                    //Do something on the left!
                    //You also have access to the original object.
                    //If you want to use it just cast it (String) dataObject
                    Toast.makeText(AppHome.this, "left", Toast.LENGTH_SHORT).show();
                }

                @Override
                public void onRightCardExit(Object dataObject) {
                    Toast.makeText(AppHome.this, "right", Toast.LENGTH_SHORT).show();
                }

                @Override
                public void onAdapterAboutToEmpty(int itemsInAdapter) {
                    // Ask for more data here
                    aList.add("XML ".concat(String.valueOf(i)));
                    arrayAdapter.notifyDataSetChanged();
                    Log.d("LIST", "notified");
                    i++;
                }

                @Override
                public void onScroll(float scrollProgressPercent) {
                }
            });

        }
    }


    public void showPopup (View v){
        PopupMenu popup = new PopupMenu(this, v);
        popup.setOnMenuItemClickListener(this);
        popup.inflate(R.menu.dropdown_menu1);
        popup.show();
    }

    @Override
    public boolean onMenuItemClick (MenuItem item){
        switch (item.getItemId()) {
            case R.id.item1:
                Toast.makeText(this, "Item 1 clicked", Toast.LENGTH_SHORT).show();
                return true;
            case R.id.item2:
                Toast.makeText(this, "Item 2 clicked", Toast.LENGTH_SHORT).show();
                return true;
            case R.id.item3:
                Toast.makeText(this, "Item 3 clicked", Toast.LENGTH_SHORT).show();
                return true;
            case R.id.item4:
                Toast.makeText(this, "Item 4 clicked", Toast.LENGTH_SHORT).show();
                return true;
            default:
                return false;
        }
    }
}

Answer 1

请在runOnUiThread内设置适配器

        runOnUiThread(new Runnable() {
        @Override
        public void run() {
            flingContainer.setAdapter(arrayAdapter);
        }
    });

并检查数组中是否包含值。希望这能解决你的问题