當我嘗試搜索HashMap時沒有任何反應

Question

我正在嘗試實現一項功能，該功能使我可以搜索所有歌曲，這些歌曲都存儲在名為songsList的HashMap中。 我已經成功實現了songsList HashMap。 我嘗試使用當用戶單擊搜索圖標時輸入的由用戶鍵入的字符串來過濾結果，但是沒有任何反應。

有什么想法為什么SongsList HashMap沒有被過濾？

我嘗試區分大小寫和不區分大小寫的搜索。 我嘗試在完整和准確的歌曲標題中搜索幾首歌曲。 因此，我認為這不是我要測試的搜索字符串，而是我代碼中的某些問題。

PlaylistActivity.java

import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Locale;

public class PlayListActivity extends ListActivity {

    private EditText editSearch;
    private ImageView searchIcon;
    private ListAdapter adapter;
    private ArrayList<HashMap<String, String>> songsListData;
    private boolean userEnteredSearchString = false;

    // Songs playlist_item
    public ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
    public ArrayList<HashMap<String, String>> filteredSongsList = new ArrayList<HashMap<String, String>>();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.playlist);

        songsListData = new ArrayList<HashMap<String, String>>();

        final SongsManager songsManager = new SongsManager();
        // get all songs from SD card
        this.songsList = songsManager.getPlayList();

        createListViewUsingSongs();


        // Set up the layout elements for this activity
        editSearch = (EditText) findViewById(R.id.search);
        searchIcon = (ImageView) findViewById(R.id.search_icon);

        // Capture Text in EditText when user clicks search icon
        searchIcon.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                String text = editSearch.getText().toString().toLowerCase(Locale.getDefault());
                filteredSongsList = songsManager.filter(text);
                userEnteredSearchString = true;
                createListViewUsingSongs();
            }
        });

        // selecting single ListView item
        ListView listView = getListView();
        // listening to single playlist_item item click
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                                            @Override
                                            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                                                // getting list item index
                                                int songIndex = position;

                                                // Starting new intent
                                                Intent intent = new Intent(getApplicationContext(), MainActivity.class);
                                                // Sending songIndex to PlayerActivity
                                                intent.putExtra("songIndex", songIndex);
                                                setResult(100, intent);
                                                // Closing PlayListView
                                                finish();
                                            }
                                        }

        );
    }

    private void createListViewUsingSongs() {

        if (userEnteredSearchString) {
            // looping through playlist
            for (int i = 0; i < filteredSongsList.size(); i++){
                // creating new HashMap
                HashMap<String, String> song = songsList.get(i);
                // adding HashList to ArrayList
                songsListData.add(song);
            }
        } else {
            // looping through playlist
            for (int i = 0; i < songsList.size(); i++){
                // creating new HashMap
                HashMap<String, String> song = songsList.get(i);
                // adding HashList to ArrayList
                songsListData.add(song);
            }
        }

        // Adding menuItems to ListView
        adapter = new SimpleAdapter(this, songsListData,
                R.layout.playlist_item, new String[]{"songTitle"}, new int[]{
                R.id.songTitle});

        setListAdapter(adapter);
    }
}

SongsManager.java

import java.io.File;
import java.io.FilenameFilter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Locale;

public class SongsManager {

    private HashMap<String, String> song;
    private String songString;

    // SDCard Path
    final String MEDIA_PATH = "/storage/extSdCard/music";
    private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
    private ArrayList<HashMap<String, String>> filteredSongsList = new ArrayList<HashMap<String, String>>();


    // Constructors
    public SongsManager(String song) {
        this.songString = songString;
    }

    public SongsManager() {
    }

    /**
     * Function to read all mp3 files from sdcard
     * and store the details in ArrayList
     */
    public ArrayList<HashMap<String, String>> getPlayList() {
        File home = new File(MEDIA_PATH);

        if (home.listFiles(new FileExtensionFilter()).length > 0) {
            for (File file : home.listFiles(new FileExtensionFilter())) {
                HashMap<String, String> song = new HashMap<String, String>();
                song.put("songTitle", file.getName().substring(0, (file.getName().length() - 4)));
                song.put("songPath", file.getPath());

                // Adding each song to SongList
                songsList.add(song);
            }
        }
        // return songs playlist_item array
        return songsList;
    }

    public String getSong() {
        return this.songString;
    }

    /**
     * Class to filter files which are having .mp3 extension
     */
    class FileExtensionFilter implements FilenameFilter {
        public boolean accept(File dir, String name) {
            return (name.endsWith(".mp3") || name.endsWith(".MP3") || name.endsWith(".wma"));
        }
    }

    // Filter Class
    public ArrayList<HashMap<String, String>> filter(String searchString) {
        searchString = searchString.toLowerCase(Locale.getDefault());

        songsList.clear();
        songsList = getPlayList();

        //searchString is empty, so show all songs in results
        if (searchString.length() == 0) {

            if (filteredSongsList != null){
                filteredSongsList.clear();
            }
            filteredSongsList = songsList;
        }

        //only return songs that match the search string
        else {

            if (filteredSongsList != null){
                filteredSongsList.clear();
            }

            for (HashMap<String, String> song : songsList) {
                if (song != null) {
                    String songTitle = song.get("songTitle");
                    if (songTitle.toLowerCase().contains(searchString)) {
                        filteredSongsList.add(song);
                    }
                }
            }
        }

        return filteredSongsList;
    }
}

playList.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent"
              android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    <EditText
        android:id="@+id/search"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="4"
        android:hint="Type song &amp; click search icon"
        android:inputType="text"
        android:maxLength="40">
        <requestFocus />
    </EditText>

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/search_icon"
        android:layout_weight="1"
        android:src="@drawable/ic_search"/>

    </LinearLayout>

    <ListView
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:divider="#242424"
        android:dividerHeight="1dp"
        android:listSelector="@drawable/list_selector" />

</LinearLayout>

可以在Github上下載完整的代碼： https : //github.com/jogold9/Simple_Music_Player

Answer 1

解決：搜索一直songsListData.clear();都很好，但是我忽略了songsListData.clear();

因此，在刷新適配器時，將顯示完整的數據集而不是已過濾的數據集。

不要害怕每個人都使用調試器。 如果我遵循這個簡單的建議，我本可以節省幾個小時。

import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Locale;

public class PlayListActivity extends ListActivity {

    private EditText editSearch;  //search text input by user
    private ImageView searchIcon;
    public SimpleAdapter simpleAdapter;
    private ListView listView;
    private ArrayList<HashMap<String, String>> songsListData;
    public ArrayList<HashMap<String, String>> songsList = new ArrayList<>();  //stores all the songs
    public ArrayList<HashMap<String, String>> filteredSongsList = new ArrayList<>();  //stores songs that match search
    private int songsAddedCounter = 0;  //counter for debugging -> are songs being added to list?

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.playlist);

        // Set up the layout elements for this activity
        editSearch = (EditText) findViewById(R.id.search);
        searchIcon = (ImageView) findViewById(R.id.search_icon);

        songsListData = new ArrayList<>();  //Stores all the songs to put into ListView

        final SongsManager songsManager = new SongsManager();
        // get all songs from SD card
        this.songsList = songsManager.getPlayList();  //gets all the songs from the phone and puts them in the HashMap

        createListViewUsingSongs();  //draws the ListView on the screen using the songsList HashMap

        // selecting single ListView item
        listView = getListView();

        // listening to single playlist_item item click
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                                            @Override
                                            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                                                int songIndex = position; // getting list item index

                                                // Starting new intent
                                                Intent intent = new Intent(getApplicationContext(), MainActivity.class);
                                                // Sending songIndex to PlayerActivity
                                                intent.putExtra("songIndex", songIndex);
                                                setResult(100, intent);
                                                // Closing PlayListView
                                                finish();
                                            }
                                        }

        );

        /**
         * When user clicks search icon, execute a search, then update the ListView simpleAdapter
         */
        searchIcon.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                String text = editSearch.getText().toString().toLowerCase(Locale.getDefault());
                filteredSongsList = songsManager.filter(text);
                updateListViewUsingSongs();
            }
        });
    }

    private void createListViewUsingSongs() {
        // looping through playlist
        for (int i = 0; i < songsList.size(); i++) {
            // creating new HashMap
            HashMap<String, String> song = songsList.get(i);
            // adding HashList to ArrayList
            songsListData.add(song);

        }

        // Adding menuItems to ListView
        simpleAdapter = new SimpleAdapter(this, songsListData,
                R.layout.playlist_item, new String[]{"songTitle"}, new int[]{
                R.id.songTitle});

        setListAdapter(simpleAdapter);
    }

    private void updateListViewUsingSongs() {

        songsAddedCounter = 0;
        songsListData.clear();  //super important that we start from zero, and add only the filtered songs!

        // looping through playlist
        for (int i = 0; i < filteredSongsList.size(); i++) {
            // creating new HashMap
            HashMap<String, String> song = filteredSongsList.get(i);
            // adding HashList to ArrayList
            songsListData.add(song);
            songsAddedCounter++;
        }
        Toast.makeText(getApplicationContext(), "Search results: " + songsAddedCounter + " songs", Toast.LENGTH_SHORT).show();

        simpleAdapter = null;

        simpleAdapter = new SimpleAdapter(this, songsListData,
                R.layout.playlist_item, new String[]{"songTitle"}, new int[]{
                R.id.songTitle});


        setListAdapter(simpleAdapter);
        simpleAdapter.notifyDataSetChanged();
    }
}