从sqlite获取的数据未在recyclerview中显示

时间:2018-12-20 10:40:40

标签: java android database sqlite firebase

    messageList = (RecyclerView) findViewById(R.id.message_list);
    mRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_layout);
    linearLayoutManager = new LinearLayoutManager(getApplicationContext());

    messageList.setLayoutManager(linearLayoutManager);

    mAdapter = new MessagesAdapter(messages);
    messageList.setAdapter(mAdapter);

final MainData mHelper = new MainData(this);
    final Cursor csr = mHelper.getAllQuestions3();
            sqlite = mDatabaseReference.child("Messages").child(MessageSenderId).child(MessageRecieverId);
            valueEventListener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
                    for (DataSnapshot ds : dataSnapshot.getChildren()) {

//I add the data from firebase to SQLITE here 


                while (csr.moveToNext()) {
                    String mSender = csr.getString(csr.getColumnIndex(KEY_SENDER));
                    String mMessage = csr.getString(csr.getColumnIndex(KEY_MESSAGE));
                    long mTime = csr.getLong(csr.getColumnIndex(KEY_TIME));
                    String mSeen = csr.getString(csr.getColumnIndex(KEY_SEEN));
                    String mTimer = csr.getString(csr.getColumnIndex(KEY_TIMER));
                    String mType = csr.getString(csr.getColumnIndex(KEY_TYPE));

                    messages.add(new SQLiteHelper(mSender, mMessage, mType, mSeen, mTimer, mTime));
                    mAdapter.notifyDataSetChanged();
                }
                    mDatabaseReference.child("Messages").child(MessageSenderId).child(MessageRecieverId).setValue(null);

        }
            @Override
            public void onCancelled(DatabaseError databaseError) {
        }
    };
            sqlite.addListenerForSingleValueEvent(valueEventListener);

适配器

public class MessagesAdapter extends RecyclerView.Adapter<MessagesAdapter.MessageViewHolder>{
ChatData mHelper;
Cursor csr;
private List<SQLiteHelper> mMessagesHelperList;
private FirebaseAuth mAuth;


public MessagesAdapter(List<SQLiteHelper> MessagesHelperList) {
    this.mMessagesHelperList = MessagesHelperList;
}


public class MessageViewHolder extends RecyclerView.ViewHolder{
    public TextView messageText;


    public MessageViewHolder(View view) {
        super(view);
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(view.getContext());


        mHelper = new ChatData(view.getContext(),"MessagePlus",null,1);
        csr = mHelper.getAllQuestions3();

        messageText = (TextView)view.findViewById(R.id.message_text_layout);
    }
}

@Override
public MessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View V = LayoutInflater.from(parent.getContext()).inflate(R.layout.custom_activity_chat,parent,false);
    mAuth = FirebaseAuth.getInstance();
    return new MessageViewHolder(V);
}

@Override
public void onBindViewHolder(final MessageViewHolder holder, int position) {
    SQLiteHelper messagesHelper = mMessagesHelperList.get(position);

       holder.messageText.setText(messagesHelper.getMessage());
    }

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

我还有另一个活动,我获取sqlite数据并将其显示在recyclerview中,并且可以正常工作,并且我已经达到了相同的方式。在这里它也可以正常工作,但是后来我添加了一些功能并移动了一些代码,现在它不起作用了,我已经多次检查了整个代码,但是仍然找不到为什么它不起作用...

表和行与数据一起存在,并且列表的大小也不为空

当我在其中添加Logs时,才发现该适配器没有被调用。那就是问题所在,但idk为什么如此

1 个答案:

答案 0 :(得分:0)

您的问题是,您要将多余的消息添加到首次创建适配器的列表中,因此

代替

messages.add(new SQLiteHelper(mSender, mMessage, mType, mSeen, mTimer, mTime));
mAdapter.notifyDataSetChanged();

mAdapter.add(new SQLiteHelper(mSender, mMessage, mType, mSeen, mTimer, mTime));

在适配器中,您必须添加类似的添加功能

public void add(SQLiteHelper item){
    if(mMessagesHelperList!=null){
        mMessagesHelperList.add(item);
        notifyDataSetChanged();
    }
}

您的代码上有太多“垃圾”,在ValueEventListener上,您试图读取游标而不是ds(DataSnapshot)的值。所以可能您的光标是空的。如果光标为空,则不会在适配器中添加任何项目,因此适配器中没有要显示的项目,因此不会正确调用onBindViewHolder