recyclerview变空后如何设置view的可见性

Question

我正在尝试将与 recyclerview 位于同一片段中的视图的可见性动态设置为不可见，当 recyclerview 变为 empty.The 问题是我正在从中删除一个项目适配器内的 recyclerview 虽然可见性必须在 fragment.I 内设置也实现了 "swipe to delete" recyclerview 项目，但那是在带有 rv 的片段内以及需要变得不可见的视图并且它工作正常.

从适配器中删除：

holder.shoppingCartDelete.setOnClickListener(new View.OnClickListener() {
 @Override
        public void onClick(View v) {
            int holderPosition = holder.getAdapterPosition();
            removeItem(holderPosition, v.getContext());
            MainActivity.shoppingCartDatabase.shoppingCartDao().delete(currentItem);

        }
    });

private void removeItem(int position, Context context) {
    shoppingCartList.remove(position);
    if (shoppingCartList.isEmpty()) {
        Toast.makeText(context, "Nu mai exista niciun produs in cos", Toast.LENGTH_LONG).show();

    // SET VISIBILITY

    }
    notifyItemRemoved(position);
}

从片段中删除-删除最后一项后可见性发生变化：

new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
        @Override
        public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
            return false;
        }

        @Override
        public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
            int position = viewHolder.getAdapterPosition();
            MainActivity.shoppingCartDatabase.shoppingCartDao().delete(shoppingCartList.get(position));
            shoppingCartList.remove(position);
            shopAdapter.notifyDataSetChanged();
            verifyIfRecyclerViewIsEmpty(shopAdapter, recyclerView);
        }
    }).attachToRecyclerView(recyclerView);

其中 verifyIftheRecyclerViewIsEmpty(shopAdapter, recyclerView) 是可见性的方法：

 private void verifyIfRecyclerViewIsEmpty(RecyclerView.Adapter adapter, RecyclerView recyclerView) {
    if (adapter.getItemCount() == 0) {
        constraintLayout.setVisibility(View.GONE);
        recyclerView.setVisibility(View.GONE);
        textView.setVisibility(View.VISIBLE);
        btnAdd.setVisibility(View.VISIBLE);
    } else {
        constraintLayout.setVisibility(View.VISIBLE);
        recyclerView.setVisibility(View.VISIBLE);
        textView.setVisibility(View.GONE);
        btnAdd.setVisibility(View.GONE);
    }
}

Answer 1

尝试使用此解决方案中提到的 RecyclerViewEmptySupport：

Answer 2

创建接口 OnItemListener 确保在片段中实现它，并在方法 onEmpty

verifyIfRecyclerViewIsEmpty

public interface OnItemListener {

    void onEmpty();
}

在您的适配器中创建侦听器

    private OnItemListener mOnItemListener;

    public void setItemListener(IOnItemClickedListener listener) {
        mOnItemListener = listener;
    }

适配器中的更新方法 removeItem

private void removeItem(int position, Context context) {
    shoppingCartList.remove(position);
    if (shoppingCartList.isEmpty()) {
        Toast.makeText(context, "Nu mai exista niciun produs in cos", Toast.LENGTH_LONG).show();
        if (mOnItemListener != null) {
            mOnItemListener.onEmpty()
        }
    }
    notifyItemRemoved(position);
}

Answer 3

在新文件中创建一个interface：

public interface onShoppingItemRemovedListener{

void onRecyclerViewEmpty();

}

在您的 adapter 中执行此操作：

class YourAdapter extends .........{

//add this
private onShoppingItemRemovedListener listener;
.....
.....


//in the constructor
public YourAdapter (onShoppingItemRemovedListener listener,..............){

this.listener = listener;
......
......
......

}


//when you delete item do this

private void removeItem(int position, Context context) {
    shoppingCartList.remove(position);
    if (shoppingCartList.isEmpty()) {
        Toast.makeText(context, "Nu mai exista niciun produs in cos", Toast.LENGTH_LONG).show();

     //at this point the recyclerview is empty, so notify the fragment
     listener.onRecyclerViewEmpty();

    }

}


}

最后在 fragment 中实现 interface 并传递给 adapter:

class YourFragement extends ........  implements onShoppingItemRemovedListener{


//now when you initialize the adapter pass the listener like this

adapter = new YourAdapter(this,...........);
.....
.....



//override this
@Override
public void onRecyclerViewEmpty(){

//this is triggered when the recycler view is completely empty

constraintLayout.setVisibility(View.GONE);
recyclerView.setVisibility(View.GONE);
textView.setVisibility(View.VISIBLE);
btnAdd.setVisibility(View.VISIBLE);


}


}

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