recyclerview变空后如何设置视图的可见性

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当 recyclerview 变空时不可见。问题是我正在从 recyclerview 中删除一个项目适配器，而可见性必须在片段内设置。我还实现了“滑动删除”recyclerview 项目，但那是在带有 rv 的片段内，并且视图需要变得不可见并且它工作正常。

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了变化：

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);

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：

https://stackoverflow.com/a/30415582/5434762

Answer 2

1. 创建接口OnItemListener确保你在你的片段中实现它，并在方法onEmpty中调用verifyIfRecyclerViewIsEmpty

public interface OnItemListener {

    void onEmpty();
}

1. 在您的适配器中创建监听器

    private OnItemListener mOnItemListener;

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

1. 在您的适配器中更新方法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interface：

public interface onShoppingItemRemovedListener{

void onRecyclerViewEmpty();

}

在您的adapter 中执行以下操作：

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);


}


}