显示错误"ViewHolder"是一个抽象类，无法实例化

Question

我正在尝试构建一个自定义的recyclerView适配器，但它在onCreateViewHolder中显示错误。

如何实例化抽象类？

我的代码有什么问题？

我也检查了其他答案，都说你的名字一定是重复的，或者你导入了错误的类，但都没有帮助。

考虑到我正处于学习阶段，一个建议会很好。

public class RegisteredRecyclerAdapter extends RecyclerView.Adapter<RegisteredRecyclerAdapter.ViewHolder> {
public Context context;
private FirebaseAuth firebaseAuth;
private FirebaseFirestore firebaseFirestore;


@NonNull
@Override
public RegisteredRecyclerAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.registered_item_listview,parent,false);
context = parent.getContext();
firebaseFirestore = FirebaseFirestore.getInstance();
firebaseAuth = FirebaseAuth.getInstance();
return  new RecyclerView.ViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull RegisteredRecyclerAdapter.ViewHolder holder, int position) {
}
@Override
public int getItemCount() {
return 0;
}

public class ViewHolder extends RecyclerView.ViewHolder{
public ViewHolder(@NonNull View itemView) {
super(itemView);
}

}

}

Answer 1

您正在尝试在onCreateViewHolder()方法中创建RecycleView.ViewHolder而不是RegisteredRecyclerAdapter.ViewHolder的实例。由于RecycleView.ViewHolder是一个abstract类，因此会出现此错误。

Answer 2

使用return new ViewHolder(view);

Answer 3

正如@Amin所说，您在onCreateViewHolder((中尝试在下方进行无效返回

@NonNull
@Override
public RegisteredRecyclerAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.registered_item_listview,parent,false);
context = parent.getContext();
firebaseFirestore = FirebaseFirestore.getInstance();
firebaseAuth = FirebaseAuth.getInstance();
return  new RegisteredRecyclerAdapter.ViewHolder(view);  //change here
}