Question

我正在制作一个聊天应用程序，希望用户能够从Firebase数据库中删除聊天记录和消息以下是我尝试使用一些代码删除消息的消息适配器的代码，当我长时间单击消息时，它工作正常，但是当我重新登录到应用程序时，消息又回来了。我使用Firebase数据库

package com.paddi.paddi.paddi;

import android.graphics.Color;
import android.support.v7.widget.RecyclerView;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import com.squareup.picasso.Picasso;

import java.util.List;

import de.hdodenhof.circleimageview.CircleImageView;

/**
 * Created by paddi on 15/11/2017.
 */

public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.MessageViewHolder>
{
    private List<Messages> userMessagesList;

    private FirebaseAuth mAuth;
    private DatabaseReference UsersDatabaseReference;







    public MessageAdapter(List<Messages> userMessagesList)
    {
        this.userMessagesList = userMessagesList;

    }


// I tried using this to delete the chats it works but every time i log into the app again the messages re-appear


    public void delete(int position){


        userMessagesList.remove(position);
        notifyItemRemoved(position);





    }




    @Override
    public MessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
    {

        View V = LayoutInflater.from(parent.getContext())
                                .inflate(R.layout.messages_layout_of_users, parent, false);


        mAuth = FirebaseAuth.getInstance();




        return new MessageViewHolder(V);



    }





    @Override
    public void onBindViewHolder(final MessageViewHolder holder, int position)
    {


        String message_sender_id = mAuth.getCurrentUser().getUid();
            Messages messages = userMessagesList.get(position);

        String fromUserId = messages.getFrom();
        String fromMessageType = messages.getType();

        UsersDatabaseReference = FirebaseDatabase.getInstance().getReference().child("Users").child(fromUserId);
        UsersDatabaseReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot)
            {
                String userName = dataSnapshot.child("user_name").getValue().toString();
                String userImage = dataSnapshot.child("user_thumb_image").getValue().toString();

                Picasso.with(holder.ReceiverProfileImage.getContext()).load(userImage)
                        .fit().centerInside().placeholder(R.drawable.default_profile).into(holder.ReceiverProfileImage);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });


        if (fromMessageType.equals("text"))
        {
            holder.ReceiverMessageText.setVisibility(View.INVISIBLE);
            holder.messagePicture.setVisibility(View.INVISIBLE);
            holder.ReceiverProfileImage.setVisibility(View.INVISIBLE);
            holder.SenderMessageText.setVisibility(View.INVISIBLE);
            // You comment this last line out in case of any errors

            if (fromUserId.equals(message_sender_id))
            {
                // You comment this first line out in case of any errors
                holder.SenderMessageText.setVisibility(View.VISIBLE);
                holder.SenderMessageText.setBackgroundResource(R.drawable.sender_message_text_background);
                holder.SenderMessageText.setTextColor(Color.WHITE);
                holder.SenderMessageText.setGravity(Gravity.START);
                holder.SenderMessageText.setText(messages.getMessage());
            }

            else
            {

                holder.SenderMessageText.setVisibility(View.INVISIBLE);

                holder.ReceiverMessageText.setVisibility(View.VISIBLE);
                holder.ReceiverProfileImage.setVisibility(View.VISIBLE);
                holder.messagePicture.setVisibility(View.VISIBLE);

                holder.ReceiverMessageText.setBackgroundResource(R.drawable.receiver_message_text_background);
                holder.ReceiverMessageText.setTextColor(Color.WHITE);
                holder.ReceiverMessageText.setGravity(Gravity.START);
                holder.ReceiverMessageText.setText(messages.getMessage());
            }

           // holder.messageText.setText(messages.getMessage());
        }


    else
    {
          //  holder.messageText.setVisibility(View.INVISIBLE);
           // holder.messageText.setPadding(0,0,0,0);

//            holder.messagePicture.setForegroundGravity(22);
        Picasso.with(holder.ReceiverProfileImage.getContext()).load(messages.getMessage())
                .placeholder(R.drawable.default_profile).into(holder.messagePicture);
    }



}



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


public class MessageViewHolder extends RecyclerView.ViewHolder implements View.OnLongClickListener
{
    public TextView SenderMessageText, ReceiverMessageText;
    public CircleImageView ReceiverProfileImage;
    public ImageView messagePicture;



    public MessageViewHolder(View view) {
        super(view);

        SenderMessageText = (TextView) itemView.findViewById(R.id.sender_message_text);
        ReceiverMessageText = (TextView) itemView.findViewById(R.id.receiver_message_text);
        messagePicture = (ImageView) view.findViewById(R.id.message_image_view);
        ReceiverProfileImage = (CircleImageView) view.findViewById(R.id.messages_profile_image);



        SenderMessageText.setOnLongClickListener(this);
        ReceiverMessageText.setOnLongClickListener(this);
        messagePicture.setOnLongClickListener(this);

    }


    @Override
    public boolean onLongClick(View v) {
        delete(getAdapterPosition());
        return true;

    }
}

}

这是我的消息树数据库的屏幕截图：

Answer 1

这似乎是删除消息的代码：

public void delete(int position){
    userMessagesList.remove(position);
    notifyItemRemoved(position);
}

这仅从适配器而不是从数据库中删除消息。因此，当您重新启动应用程序时，该消息会再次出现。

要永久删除消息，您还必须将其从数据库中删除。由于您没有共享如何加载数据，因此很难提供确切的代码。但这会是这样的：

FirebaseDatabase.getInstance().getReference("messages").child("key_of_message").removeValue();

如何从Firebase数据库中删除消息？

1 个答案: