Question

我尝试使用可扩展列表视图创建回溯应用程序。起初它正确播放但我发现了一个错误，当我尝试点击它仍然播放时的标题。我不知道如何避免这首歌播放过两次。我不知道做对了，已经尝试使用isPlaying但失败了。有人帮助我。

public class BacktrackActivity extends Activity {

    MediaPlayer mp;
    ExpandableListAdapter listAdapter;
       ExpandableListView expListView;
       List<String> listDataHeader;
       HashMap<String, List<String>> listDataChild;
       Context context;
       public ImageButton stop;
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.backtrack);

       //    final int[] blues = {R.raw.satch_boogie, R.raw.satch_boogie};
       //   mp = MediaPlayer.create(this, R.raw.satch_boogie);

           // get the listview
           expListView = (ExpandableListView) findViewById(R.id.genre_list);

           // preparing list data
           prepareListData();

           listAdapter = new ExpandableListAdapter(this,listDataHeader,listDataChild);

           // setting list adapter
           expListView.setAdapter(listAdapter);

           stop = (ImageButton) findViewById(R.id.imageButton1);
           stop.setOnClickListener(new OnClickListener() {

               @Override
               public void onClick(View view) {

                   mp.stop();
                   mp.reset();
               }
           });


        expListView.setOnGroupClickListener(new OnGroupClickListener() {

           public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition,
                   long id) {
               // TODO Auto-generated method stub
               return false;
           }
       });

        expListView.setOnGroupExpandListener(new OnGroupExpandListener() {

               @Override
               public void onGroupExpand(int groupPosition) {
                   Toast.makeText(getApplicationContext(), "Choose your " +
                           listDataHeader.get(groupPosition) + " Backtrack",
                           Toast.LENGTH_SHORT).show();

               }
           });

     // Listview on child click listener
           expListView.setOnChildClickListener(new OnChildClickListener() {
               public boolean onChildClick(ExpandableListView parent, View v,
                       int groupPosition, int childPosition, long id) {

                   if(groupPosition == 0 && childPosition == 0){ 
                       mp.stop();
                        mp = MediaPlayer.create(BacktrackActivity.this, R.raw.satch_boogie);
                        mp.start();
                                        }
                   if(groupPosition == 0 && childPosition == 1){
                       mp =  MediaPlayer.create(BacktrackActivity.this, R.raw.top_gun);
                       mp.start();
                   }
               return false;
               }
               }); 
           }

       /*
        * Preparing the list data
        */
       private void prepareListData() {
           listDataHeader = new ArrayList<String>();
           listDataChild = new HashMap<String, List<String>>();

           // Adding child data
           listDataHeader.add("Blues");
           listDataHeader.add("Jazz");
           listDataHeader.add("Rock");
           listDataHeader.add("RnB");

           // Adding child data
           List<String> Blues = new ArrayList<String>();
           Blues.add("The Shawshank Redemption");
           Blues.add("The Godfather");
           Blues.add("The Godfather: Part II");
           Blues.add("Pulp Fiction");
           Blues.add("The Good, the Bad and the Ugly");
           Blues.add("The Dark Knight");
           Blues.add("12 Angry Men");

           List<String> Jazz = new ArrayList<String>();
           Jazz.add("The Conjuring");
           Jazz.add("Despicable Me 2");
           Jazz.add("Turbo");
           Jazz.add("Grown Ups 2");
           Jazz.add("Red 2");
           Jazz.add("The Wolverine");

           List<String> Rock = new ArrayList<String>();
           Rock.add("2 Guns");
           Rock.add("The Smurfs 2");
           Rock.add("The Spectacular Now");
           Rock.add("The Canyons");
           Rock.add("Europa Report");

           List<String> RnB = new ArrayList<String>();
           RnB.add("2 Guns");
           RnB.add("The Smurfs 2");
           RnB.add("The Spectacular Now");
           RnB.add("The Canyons");
           RnB.add("Europa Report");

           listDataChild.put(listDataHeader.get(0), Blues); // Header, Child data
           listDataChild.put(listDataHeader.get(1), Jazz);
           listDataChild.put(listDataHeader.get(2), Rock);
           listDataChild.put(listDataHeader.get(3), RnB);
}
}

Answer 1

不要使用静态create方法，而是在声明处调用MediaPlayer mp = new MediaPlayer();。然后代替create调用，执行类似的操作（您的代码会被注释以显示它的位置）：

//mp.stop();
//mp = MediaPlayer.create(BacktrackActivity.this, R.raw.satch_boogie);
mp.reset();
mp.setDataSource(BacktrackActivity.this, Uri.parse(
    // I don't know your package name...
    "android.resource://com.your.package/" + R.raw.satch_boogie));
mp.prepare();
mp.start();

仅使用MediaPlayer的一个实例应该保持多个来源一次播放。此外，请在完成后致电release()（可能在onDestroy）。

如何避免玩双安卓媒体播放器

1 个答案: