无法转换类型为 java.lang.String 的 object [Android]

Question

当我尝试检索应用程序关闭的子路径时，我只想能够在 texview 中设置子路径的值，但该应用程序始终关闭并且在 logcat 中它告诉我：无法转换 java 类型的 object .lang.String 键入 com.musicapp.owls.ClassesFolder.Recover。

显然我的问题已经在平台上创建了，但实际上我看到的答案对我没有帮助，我希望你能帮助我，如果你帮助我，我会把答案标记为已回答

        LinearLayoutManager mLayoutManager = new LinearLayoutManager(this);
        mLayoutManager.setReverseLayout(true);
        mLayoutManager.setStackFromEnd(true);
        recyclerView_album_songs.setLayoutManager(mLayoutManager);


      mDatabase = FirebaseDatabase.getInstance().getReference("Artistas/"+artist_name+"/Albumes/"+album_name);


      FirebaseRecyclerOptions<Recover> options =
                new FirebaseRecyclerOptions.Builder<Recover>()
                        .setQuery(mDatabase,Recover.class)
                        .build();



      adapter = new FirebaseRecyclerAdapter<Recover, RecyclerView.ViewHolder>(options) {
          @Override
          protected void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position, @NonNull Recover model) {

              TextView textView = holder.itemView.findViewById(R.id.song_name_txt);
              textView_album.setText(model.getName());

              textView.setText(model.getPath());    

          }

          @NonNull
          @Override
          public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
              View view = LayoutInflater.from(parent.getContext())
                      .inflate(R.layout.list_songs_inflated, parent, false);

              return new RecyclerView.ViewHolder(view) {
              };

          }


      };
  
        adapter.startListening();
        recyclerView_album_songs.setAdapter(adapter);


    }
}

恢复构造函数

public class Recover {


    public String Nombre;
    public String ImageView;
    public String ImageAlbum;
    public String NameAlbum;
    public String path;



    // Default constructor required for calls to
    // DataSnapshot.getValue(User.class)
    public Recover() {


    }


    public Recover(String Nombre, String ImageView, String imageView, String nameAlbum, String path) {
        this.Nombre = Nombre;
        this.ImageView= ImageView;
        this.ImageAlbum = imageView;
        this.NameAlbum = nameAlbum;
        this.path = path;

    }



    public String getArtist() {
        return Nombre;
    }

    public String getUrl() {
        return ImageView;
    }

    public String getImage() {
        return ImageAlbum;
    }

    public String getName() {
        return NameAlbum;
    }

    public String getPath() {
        return path;
    }

}

日志猫

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.musicapp.buhos, PID: 30375
    com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.musicapp.buhos.ClassesFolder.Recover
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(CustomClassMapper.java:436)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(CustomClassMapper.java:232)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(CustomClassMapper.java:80)
        at com.google.firebase.database.DataSnapshot.getValue(DataSnapshot.java:203)
        at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:29)
        at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:15)
        at com.firebase.ui.common.BaseCachingSnapshotParser.parseSnapshot(BaseCachingSnapshotParser.java:36)
        at com.firebase.ui.common.BaseObservableSnapshotArray.get(BaseObservableSnapshotArray.java:52)
        at com.firebase.ui.database.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:109)
        at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:149)
        at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7254)
        at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7337)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6194)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6460)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6300)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6296)
        at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2330)
        at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1631)
        at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1591)
        at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:668)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4309)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:4012)
        at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4578)
        at android.view.View.layout(View.java:23033)
        at android.view.ViewGroup.layout(ViewGroup.java:6468)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
        at android.view.View.layout(View.java:23033)
        at android.view.ViewGroup.layout(ViewGroup.java:6468)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
        at android.view.View.layout(View.java:23033)
        at android.view.ViewGroup.layout(ViewGroup.java:6468)
        at androidx.appcompat.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:536)
        at android.view.View.layout(View.java:23033)
        at android.view.ViewGroup.layout(ViewGroup.java:6468)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
        at android.view.View.layout(View.java:23033)
        at android.view.ViewGroup.layout(ViewGroup.java:6468)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
        at android.view.View.layout(View.java:23033)
        at android.view.ViewGroup.layout(ViewGroup.java:6468)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
E/AndroidRuntime:     at com.android.internal.policy.DecorView.onLayout(DecorView.java:804)
        at android.view.View.layout(View.java:23033)
        at android.view.ViewGroup.layout(ViewGroup.java:6468)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3599)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:3067)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:2070)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:8400)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1058)
        at android.view.Choreographer.doCallbacks(Choreographer.java:880)
        at android.view.Choreographer.doFrame(Choreographer.java:813)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1043)
        at android.os.Handler.handleCallback(Handler.java:938)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:236)
        at android.app.ActivityThread.main(ActivityThread.java:8037)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)

Answer 1

FirebaseRecyclerAdapter中的 FirebaseRecyclerAdapter 假定您要显示数据库中的子节点列表。 因此，您传递给setQuery的查询需要是选择一个或多个专辑的查询，或者您要显示的整个专辑列表。

您正在此处加载一张专辑：

mDatabase = FirebaseDatabase.getInstance().getReference("Artistas/"+artist_name+"/Albumes/"+album_name);

因此，当您将其传递给FirebaseRecyclerAdapter时，它会尝试在适配器的视图持有者中显示该相册的每个子属性。 那不是你想要的。

如果您只想显示一个相册， RecyclerView通常不是最好的小部件。 但是，如果您真的想使用它，则必须创建一个查询 select 那个专辑：

Query query = FirebaseDatabase.getInstance() 
    .getReference("Artistas/"+artist_name+"/Albumes")
    .orderByKey()
    .equaTo(album_name);

当您对 Firebase 数据库执行查询时，可能会有多个结果。 所以快照包含这些结果的列表。 即使只有一个结果，快照也会包含一个结果的列表。

所以现在您可以将query传递给 Firebase：

FirebaseRecyclerOptions<Recover> options =
    new FirebaseRecyclerOptions.Builder<Recover>()
            .setQuery(query, Recover.class)
            .build();