android - ClassCastException 自定义 ViewHolder 无法转换为另一个 Viewholder

Question

我的项目应该基于用户输入(用户发送文本、拍照或录制视频)创建多个 View ，类似于 WhatsApp 聊天 Activity ，结构几乎相同。适配器应该能够通过使用 getItemViewType() 来识别项目的 View 类型。如果尝试使用视频录制功能，它可以工作，但如果我尝试拍照或发送文本，则应用程序崩溃并出现以下错误:

java.lang.ClassCastException:AppPackage.myAdapter$TextViewHolder 无法转换为 AppPackage.myAdapter$ImageViewHolder

从输入中获取的所有数据都添加到列表中，然后传递给 onBindViewHolder

已经尝试将 onBindViewHolder(CustomViewHolder myViewHolder, int position) 更改为 onBindViewHolder(RecyclerView.ViewHolder, int position)
并在开关的每个“案例”中添加中断。还是行不通

适配器

public class myAdapter extends   
RecyclerView.Adapter<RecyclerView.ViewHolder> {

List<ModelloDati> lista;
Context context;


public class ImageViewHolder extends RecyclerView.ViewHolder {
    //ImageView mImage;
    private ImageView imageView;
    public ImageViewHolder(View itemView) {
        super (itemView);
        imageView = itemView.findViewById(R.id.immagine);
    }
}

public class TextViewHolder extends RecyclerView.ViewHolder {
    // each data item is just a string in this case
    private TextView titolo;

    public TextViewHolder(View v) {
        super(v);
        titolo = itemView.findViewById(R.id.testo);
    }
}

public class VideoViewHolder extends RecyclerView.ViewHolder {
    // each data item is just a string in this case
    private VideoView videoView;

    public VideoViewHolder(View v) {
        super(v);
        videoView = itemView.findViewById(R.id.rec);
    }
}

public myAdapter(List<ModelloDati> lista,Context context) {
    this.lista = lista;
    this.context = context;

}


@Override
public RecyclerView.ViewHolder  onCreateViewHolder(ViewGroup parent,
                                                   int viewType) {
    if (viewType == 0) {
        // create a new view
        View v =  
LayoutInflater.from(parent.getContext()).inflate(R.layout.item_chat_foto, 
parent, false);
        // set the view's size, margins, paddings and layout parameters
        ImageViewHolder vh = new ImageViewHolder(v);
        return vh;
    }
    if (viewType == 2) {
        // create a new view
        View v = 
LayoutInflater.from(parent.getContext()).inflate(R.layout.item_chat_video, 
parent, false);
        // set the view's size, margins, paddings and layout parameters
        VideoViewHolder vh = new VideoViewHolder(v);
        return vh;
    } else {
        // create a new view
        View v = 
LayoutInflater.from(parent.getContext()).inflate(R.layout.item_chat_testo,  
parent, false);
        // set the view's size, margins, paddings and layout parameters
        TextViewHolder vh = new TextViewHolder(v);
        return vh;
    }
}


@Override
public int getItemViewType(int position){

        switch (lista.get(position).getTYPE()) {
            case 0: return 0;
            case 1: return 1;
            case 2: return 2;
        }
        return 0;

    }


@Override
public int getItemCount() {
        if (lista == null)
            return 0;
        return lista.size();
    }


@Override
 public void onBindViewHolder(RecyclerView.ViewHolder myViewHolder, int 
position) {

        ModelloDati oggetto = lista.get(position);

        switch (myViewHolder.getItemViewType()) {

            case 0:
                TextViewHolder viewHolder = (TextViewHolder) myViewHolder;
                viewHolder.titolo.setText(oggetto.getTesto());
                break;

            case 1:
                ImageViewHolder imageViewHolder = (ImageViewHolder) 
myViewHolder;

imageViewHolder.imageView.setImageBitmap(oggetto.getImmagini());
                imageViewHolder.imageView.setOnClickListener(new 
View.OnClickListener() {
                    @Override
                    public void onClick(View v) {

                    }
                });

                break;


            case 2:
                VideoViewHolder videoViewHolder = (VideoViewHolder) 
myViewHolder;
                videoViewHolder.videoView.setVideoURI(oggetto.getUri());
                MediaController mediaController = new 
MediaController(context);
                mediaController.setAnchorView(videoViewHolder.videoView);

videoViewHolder.videoView.setMediaController(mediaController);
                videoViewHolder.videoView.requestFocus();
                videoViewHolder.videoView.start();

                videoViewHolder.videoView.setOnClickListener(new 
View.OnClickListener() {
                    @Override
                    public void onClick(View v) {

                    }
                });
                break;

                default:
                    viewHolder = (TextViewHolder) myViewHolder;
                    viewHolder.titolo.setText("ERRORE");


        }

    }


}

日志猫

2019-05-21 10:24:18.728 11089-11089/com.sinfo.chat E/AndroidRuntime: FATAL  
EXCEPTION: main
Process: com.sinfo.chat, PID: 11089
java.lang.ClassCastException: com.sinfo.chat.myAdapter$TextViewHolder cannot be  
cast to com.sinfo.chat.myAdapter$ImageViewHolder
    at com.sinfo.chat.myAdapter.onBindViewHolder(myAdapter.java:119)
    at 

android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
    at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
    at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
    at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
    at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
    at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
    at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:587)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
    at android.support.v7.widget.RecyclerView.onMeasure(RecyclerView.java:3336)
    at android.view.View.measure(View.java:23169)
    at android.support.constraint.ConstraintLayout.internalMeasureChildren(ConstraintLayout.java:1227)
    at android.support.constraint.ConstraintLayout.onMeasure(ConstraintLayout.java:1572)
    at android.view.View.measure(View.java:23169)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:143)
    at android.view.View.measure(View.java:23169)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
    at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:401)
    at android.view.View.measure(View.java:23169)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at android.view.View.measure(View.java:23169)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1535)
    at android.widget.LinearLayout.measureVertical(LinearLayout.java:825)
    at android.widget.LinearLayout.onMeasure(LinearLayout.java:704)
    at android.view.View.measure(View.java:23169)
    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6749)
    at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
    at com.android.internal.policy.DecorView.onMeasure(DecorView.java:716)
    at android.view.View.measure(View.java:23169)
    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2725)
    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1575)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1858)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1463)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7190)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
    at android.view.Choreographer.doCallbacks(Choreographer.java:761)
    at android.view.Choreographer.doFrame(Choreographer.java:696)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6718)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Answer 1

ImageViewHolder使用类型 0 创建在 onCreateViewHolder并以 1 类型类型转换在 onBindViewHolder .使用常量而不是 float 魔数(Magic Number)