删除项目后Recyclerview不刷新答案

【问题标题】：Recyclerview not refreshing after removing an item删除项目后Recyclerview不刷新
【发布时间】：2019-02-21 06:36:50
【问题描述】：

删除项目后，我的回收站视图未更新。这个 recyclerView 在一个片段内。我已经尝试了所有方法，但没有任何效果。

片段类中的适配器声明

    notificationsTabAdapter = new NotificationsTabAdapter(getContext(), R.id.notificationsRecyclerView,
                notificationItemsList, cListner);
        layoutManager = new LinearLayoutManager(getContext());
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setAdapter(notificationsTabAdapter);

RecyclerViewAdapter：

public class NotificationsTabAdapter extends RecyclerView.Adapter<NotificationsTabAdapter.NotificationItemHolder> {

Boolean debug = false;
public static final String NOTIFICATION_ADAPTER = "NotificationAdapter";
private ArrayList<NotificationItemm> notificationItems;
private int layoutResID;
private int notificationposition;
private Context myContext;
public onNotificationItemClickListner mListner;


public interface onNotificationItemClickListner {
    void onNotificationItemDelete(int position);
}

public NotificationsTabAdapter(Context context, int resource, ArrayList<NotificationItemm> notificationList,
                               onNotificationItemClickListner listner) {
    myContext = context;
    layoutResID = resource;
    notificationItems = notificationList;
    notificationposition = 0;
    this.mListner = listner;
}

@NonNull
@Override
public NotificationItemHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {

    View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.notifications_tab_item, viewGroup, false);
    NotificationsTabAdapter.NotificationItemHolder evh = new NotificationsTabAdapter.NotificationItemHolder(view, mListner);
    return evh;
}

@Override
public void onBindViewHolder(@NonNull final NotificationItemHolder notificationItemHolder, final int position) {

    final NotificationItemm currentItem = notificationItems.get(position);

    notificationItemHolder.mNotificationTextView.setText(currentItem.getNotification_name());
    notificationItemHolder.mNotificationURL = currentItem.getNotification_link();
    notificationItemHolder.mNotificationDate = currentItem.getNotification_date();
    notificationItemHolder.mNotificationRT = currentItem.getNotification_rT();

    notificationItemHolder.mNotificaionHolderLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    //to delete the notification
    notificationItemHolder.imageDelete.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            deleteNotification(currentItem);

            mListner.onNotificationItemDelete(position);
        }
    });
}

@Override
public int getItemCount() {
    return notificationItems.size();
}

//Delete from View

public void deleteNotification(NotificationItemm todelete) {
    int notificationPosition = notificationItems.indexOf(todelete);
    notificationItems.remove(notificationPosition);
    notifyItemRemoved(notificationPosition);
    notifyItemChanged(notificationPosition);
    notifyDataSetChanged();
    notifyItemRemoved(notificationPosition);
    notifyItemChanged(notificationPosition);

    if (notificationItems.isEmpty()) {

    }
}

/**
 * VIEW HOLDER =================================================================================
 **/

public class NotificationItemHolder extends RecyclerView.ViewHolder {
    RelativeLayout mNotificaionHolderLayout;
    RelativeLayout notificationParentRelative;
    ImageView imageDelete;
    TextView mNotificationTextView;
    String mNotificationURL;
    String mNotificationDate;
    String mNotificationRT;

    public NotificationItemHolder(@NonNull View itemView, onNotificationItemClickListner listner) {

        super(itemView);
        mNotificationTextView = itemView.findViewById(R.id.NotificationTextView);
        mNotificaionHolderLayout = itemView.findViewById(R.id.notification__item_container);
        imageDelete = itemView.findViewById(R.id.notification_delete_image);
        notificationParentRelative = itemView.findViewById(R.id.rlNotificLayout);
        mNotificationRT = null;
        mNotificationURL = null;
        mNotificationDate = null;
    }
}

}

当我调试项目时，我可以看到该项目实际上是从 ArrayList 中删除。但在回收视图中没有更新。

删除后，如果recyclerview被滚动，被删除的item从recyclerview中移除。但不是不滚动。

【问题讨论】：

是的，即使我遇到了同样的问题
@bk7 你找到解决办法了吗？
是的，我做了一些研究
分享您的 NotificationsTabAdapter 构造函数代码，我将发布解决方案
我认为您必须在片段中设置 notifydatasetchanged() 并使用回调并再次将适配器设置为您的 recyclerview。

标签： android android-recyclerview

【解决方案1】：

试试这个。希望对你有用。

notificationItemHolder.imageDelete.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
           notificationItems.remove(position);
           notifyDataSetChanged();
    }

【讨论】：

可能是项目对象的问题（它可能引用不同的对象）。您可以发布完整的适配器类吗？所以我们可以帮助你

【解决方案2】：

在您的 NotificationsTabAdapter 中进行以下更改

   NotificationsTabAdapterListener notificationsTabAdapterListener;

   public interface NotificationsTabAdapterListener { // create an interface
        void onItemsDeleted(int position); // create callback function
    }

public NotificationsTabAdapter(Context context, int resource, ArrayList<NotificationItemm> notificationList,
                           NotificationsTabAdapterListener notificationsTabAdapterListener) {
myContext = context;
layoutResID = resource;
notificationItems = notificationList;
notificationposition = 0;
this.notificationsTabAdapterListener = notificationsTabAdapterListener;

}

      notificationItemHolder.imageDelete.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
//perform normal remove operation here

notificationItems.remove(position);
            notificationsTabAdapterListener.onItemsDeleted(position);
        }
    });

并在您的片段中实现 NotificationsTabAdapterListener 并在覆盖方法中使用以下代码

        @Override
public void onItemsDeleted(final int position) {
    notificationsTabAdapter.notifyDataSetChanged();
    recyclerView.post(new Runnable() {
        @Override
        public void run() {
            recyclerView.smoothScrollToPosition(position);

        }
    });
}

【讨论】：

我做到了，现在我在界面中的 onNotificationItemDelete 回调上得到一个空点异常
您是否在片段中实现了 NotificationsTabAdapterListener？
并在 NotificationsTabAdapter 构造函数中传递它
是的，您传递的是 cListner 而不是 this
是的，是的，...知道了

【解决方案3】：

试试这个删除功能

public void deleteNotification(NotificationItemm todelete) {
    notificationItems.remove(todelete);
    notifyDataSetChanged();

}

【讨论】：

不，这和我写的一样，从 dataList 中删除，但 recyclerview 不刷新
告诉我如何将列表传递给 recycleView 适配器
notificationsTabAdapter = new NotificationsTabAdapter(getContext(), R.id.notificationsRecyclerView, notificationItemsList, cListner);在此行上，notificationItemsList 的类型是什么以及您如何在列表中添加数据，请分享
在 Activity/Fragment 代码中尝试这个，而不是在 RecyclerView 适配器代码中。 mAdapter.notifyDataSetChanged();
notificationItemsList 是另一个类 NotificationItemm 的对象的 ArrayList。

【解决方案4】：

作为解决方法，您可以在 FragmentClass 中调用一个方法，该方法会在您的适配器中加载新列表（已删除项目）。从您的适配器调用此方法

public void MethodInFragmentClass(NotificationItemm todelete)
{
/*
... delete item 
*/
notificationsTabAdapter = new NotificationsTabAdapter(getContext(), R.id.notificationsRecyclerView,
                notificationDeletedItemsList, cListner);

                recyclerView.setAdapter(notificationsTabAdapter);
}

【讨论】：

【解决方案5】：

在您的适配器中使用这样的回调：

private ICallback mICallback;

    public interface ICallback {

      void deleteItem(int position);
    }
    public SettingRecyclerViewAdapter(SettingMediator settingMediator, ICallback ICallback) {
        mICallback = ICallback;
        mSettingMediator = settingMediator;
    }

在你的 faragment notifydatasetchange 和 update recyclerview 中像这样：

public class YourFragment implements SettingContract.View, SettingRecyclerViewAdapter.ICallback {
.
.
.
    @Override
    public void deleteItem(int position) {

                //delete item from your list here
        mSettingRecyclerViewAdapter = new SettingRecyclerViewAdapter(yourList, this);
        mRecyclerView.setAdapter(mSettingRecyclerViewAdapter);
        mSettingRecyclerViewAdapter.notifyDataSetChanged();
    }


}

【讨论】：

【解决方案6】：

试试这个：

    notificationItemHolder.imageDelete.setTag(holder);
    notificationItemHolder.imageDelete.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            NotificationItemHolder viewholder = (NotificationItemHolder) v.getTag();
            notificationItems.remove(viewholder.getAdapterPosition());
            notifyDataSetChanged();
        }
    });

【讨论】：

【解决方案7】：

您必须将从适配器类中的 onclick 侦听器获取的位置解析为接口方法（onitemClicked()）然后，将接口类实现为 Fragment 类，并使用 [ listname.remove(position)) ] 删除我们在接口方法上的位置最终，使用 adaptername.notifyDataSetChanged() 更新 recyclerview UI；

第一步：创建接口类

public interface RecyclerviewItemClickListener {


    void onitemClicked(View v, int position);
}

第2步：将位置传递给适配器类中的接口方法

notificationItemHolder.imageDelete.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        deleteNotification(currentItem);
        //use interface method & pass the position of the list to fragment for update UI .
        recyclerviewItemClickListener.onitemClicked(v,position);
    }
});

第三步：实现fragment中的接口类&方法

@Override
    public void onitemClicked(View v, int position) {

        Listname.remove(Listname.get(position));
        RecyclerviewAdaptername.notifyDataSetChanged();
    }

【讨论】：