Question

我已在档案中搜索过我的问题，但我无法找到任何解决方案。我是编码新手，并且真的不知道为什么我的按钮接下来不起作用（单击按钮时崩溃）。这肯定是因为我的arraylist，但为什么呢？我认为我的数组列表大小是20而不是5.我知道5是根据点击的类别显示的歌曲数量，但我没有为每个类别创建新的数组列表。有帮助吗？

public class listViewOfSongs extends AppCompatActivity {

// Varaibles
public ArrayList<Songs> songs = new ArrayList<>();
String songCategory;
//Needed for getting data from MainActivity
private String data;

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

    //Getting data from main activity
    Bundle bundle = getIntent().getExtras();
    data = bundle.getString("data");

    // Display list of songs based on category chosen
    displaySongs();

}

// Method to display list of songs
public void displaySongs() {

    // Create a list of songs
    songs = new ArrayList<>();
    if (data.equals(getString(R.string.category_electronic))) {
        // Set category
        songCategory = getString(R.string.category_electronic);
        // Add songs
        songs.add(new Songs("I Don't Cry", "A Virtual Friend", 0));
        songs.add(new Songs("Light", "Hazardous",1));
        songs.add(new Songs("First", "JekK",2));
        songs.add(new Songs("Energy", "Pokki DJ",3));
        songs.add(new Songs("Pangea", "Professor Kliq",4));
    } else if (data.equals(getString(R.string.category_hiphop))) {
        // Set category
        songCategory = getString(R.string.category_hiphop);
        // Add songs
        songs.add(new Songs("Drop", "Z-Major",5));
        songs.add(new Songs("You Got Me Rocking", "Ed Napioli",6));
        songs.add(new Songs("Summertimewav", "Emcee Lynx",7));
        songs.add(new Songs("Let It Go", "Kidd Young ft. Michael John",8));
        songs.add(new Songs("Deep Club Music", "Sam Valley",9));
    } else if (data.equals(getString(R.string.category_house))) {
        // Set category
        songCategory = getString(R.string.category_house);
        // Add songs
        songs.add(new Songs("Disc Over", "Becaysi",10));
        songs.add(new Songs("Light", "Hazardous",11));
        songs.add(new Songs("Seasons", "NumBack",12));
        songs.add(new Songs("Housing", "RasL",13));
        songs.add(new Songs("Hypnotize Me", "The Artisans Beats",14));
    } else if (data.equals(getString(R.string.category_latin))) {
        // Set category
        songCategory = getString(R.string.category_latin);
        // Add songs
        songs.add(new Songs("Bony", "T.B.T ft. Bufalo El Fuete ",15));
        songs.add(new Songs("Solo Amigos", "Edward  Jay",16));
        songs.add(new Songs("Me Canse", "Harveys",17));
        songs.add(new Songs("Sola", "Mackenzie La Fuerza",18));
        songs.add(new Songs("Fallin Down", "The Madpix Project",19));
    }

    // Create an {@link SongsAdapter}, whose data source is a list of {@link Songs}. The
    // adapter knows how to create list items for each item in the list.
    SongsAdapter adapter = new SongsAdapter(this, 0, songs);

    // Find the {@link ListView} object in the view hierarchy of the {@link Activity}.
    // There should be a {@link ListView} with the view ID called list, which is declared in the
    // songs_list.xml layout file.
    final ListView listView = findViewById(R.id.list);

    // Make the {@link ListView} use the {@link SongsAdapter} we created above, so that the
    // {@link ListView} will display list items for each {@link Songs} in the list.
    listView.setAdapter(adapter);

    // Set OnClickListener on ListView to identify the item on ListView clicked by user
    // song on the ListView item clicked is passed on to player activity
    listView.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            // Getting list item index
            Intent intent = new Intent(getApplicationContext(), Player.class);
            intent.putParcelableArrayListExtra("song", songs);
            intent.putExtra("title", songs.get(position).getSongTitle());
            intent.putExtra("artist", songs.get(position).getSongArtist());
            intent.putExtra("pos", songs.get(position).getRawSong());
            intent.putExtra("index", songs.get(position));
            intent.putExtra("data", data);

            // Closing PlayListView and opening new activity
            startActivity(intent);
        }
    });

}

我的按钮下一步方法：

 btnNext = findViewById(R.id.btnNext);
    btnNext.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {
            PartyMp.stop();
            PartyMp.reset();
            pos = pos + 1;
            PartyMp = MediaPlayer.create(getApplicationContext(), rawF[pos]);
            titleOfSong.setText(String.valueOf(songs.get(pos).getSongTitle()));
            artistOfSong.setText(String.valueOf(songs.get(pos).getSongArtist()));
            PartyMp.start();
        }

    });

Answer 1

您的数组实际上包含的元素不超过5个。检查就好 if (data.equals(getString(R.string.category_hiphop))) 不允许您同时添加所有元素。您的数组同时只包含5首歌曲的一个子集。

数组列表位置和媒体播放器按钮下一个错误

1 个答案: