我试图在RecyclerView中使用多个ViewHolders,以便在运行时交换这些视图。我创建了两个扩展RecyclerView.ViewHolder的类:
MenuItemViewHolder
public class MenuItemViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView menuItemText;
public ImageView menuItemPhoto;
public RecyclerViewAdapter rva;
public MenuItemViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
rva = caller;
menuItemText = (TextView) itemView.findViewById(R.id.grid_text);
menuItemPhoto = (ImageView) itemView.findViewById(R.id.grid_image);
}
@Override
public void onClick(View view) {
Toast.makeText(view.getContext(), "Clicked Position = " + getPosition(), Toast.LENGTH_SHORT).show();
}
}
SelectedItemViewHolder
public class SelectedItemViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView menuItemText;
public ImageView menuItemPhoto;
public RecyclerViewAdapter rva;
public SelectedItemViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(this);
menuItemText = (TextView) itemView.findViewById(R.id.grid_text_full);
menuItemPhoto = (ImageView) itemView.findViewById(R.id.grid_image_full);
}
@Override
public void onClick(View view) {
Toast.makeText(view.getContext(), "Clicked Position = " + getPosition(), Toast.LENGTH_SHORT).show();
}
}
在我的RecyclerViewAdapter类的onCreateViewHolder函数中调用它们:
RecyclerViewAdapter onCreateViewHolder
// Create new views (invoked by the layout manager)
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
switch (viewType) {
case 0:
View gridItemLayout = LayoutInflater.from(parent.getContext())
.inflate(R.layout.grid_single, parent, false);
// set the view's size, margins, paddings and layout parameters
MenuItemViewHolder vh = new MenuItemViewHolder(gridItemLayout);
case 2:
View selectedItemLayout = LayoutInflater.from(parent.getContext())
.inflate(R.layout.grid_single_full, parent, false);
// set the view's size, margins, paddings and layout parameters
SelectedItemViewHolder sivh = new SelectedItemViewHolder(selectedItemLayout);
return sivh;
}
}
当我尝试运行代码时,出现此错误:
错误:(48,36)错误:RecyclerViewAdapter中的onCreateViewHolder(ViewGroup,int)无法覆盖适配器中的onCreateViewHolder(ViewGroup,int) 返回类型ViewHolder与MenuItemViewHolder不兼容 其中VH是一个类型变量: VH扩展了类Adapter
中声明的ViewHolder
所以,问题似乎是onCreateViewHolder不接受我的自定义类继承自RecyclerView.ViewHolder。我使用的是Android Studio,所以问题就在那里。我感到困惑,因为我认为Java继承可以毫无问题地处理这个问题。有人可以提出解决方案吗?
编辑:当我将onCreateViewHolder的返回类型更改为只有一个VH的MenuItemViewHolder时,一切正常。但是,当我有多个可以随时交换的VH类时,这不起作用。
答案 0 :(得分:21)
RecyclerView.Adapter
是一个参数化类,它采用单ViewHolder
类型。您的定义可能如下所示:
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MenuItemViewHolder>
应该是:
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>
不要忘记onBindViewHolder
的正确定义。您还需要覆盖getItemViewType
。
答案 1 :(得分:0)
对于那些想要完整的工作代码的人。妳去
public class YourListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private static final int LAYOUT_ONE= 0;
private static final int LAYOUT_TWO= 1;
@Override
public int getItemViewType(int position)
{
if(position==0)
return LAYOUT_ONE;
else
return LAYOUT_TWO;
}
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view =null;
RecyclerView.ViewHolder viewHolder = null;
if(viewType==LAYOUT_ONE)
{
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.one,parent,false);
viewHolder = new ViewHolderOne(view);
}
else
{
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.two,parent,false);
viewHolder= new ViewHolderTwo(view);
}
return viewHolder;
}
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {
if(holder.getItemViewType()== LAYOUT_ONE)
{
// Typecast Viewholder
// Set Viewholder properties
// Add any click listener if any
}
else {
ViewHolderOne vaultItemHolder = (ViewHolderOne) holder;
vaultItemHolder.name.setText(displayText);
vaultItemHolder.name.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
.......
}
});
}
}
//**************** VIEW HOLDER 1 ******************//
public class ViewHolderOne extends RecyclerView.ViewHolder {
public TextView name;
public ViewHolderOne(View itemView) {
super(itemView);
name = (TextView)itemView.findViewById(R.id.displayName);
}
}
//**************** VIEW HOLDER 2 ******************//
public class ViewHolderTwo extends RecyclerView.ViewHolder{
public ViewHolderTwo(View itemView) {
super(itemView);
..... Do something
}
}
}