在我的ChatActivity中，出现此异常：
java.lang.IllegalArgumentException: You must use startAt(String value), endAt(String value) or equalTo(String value) in combination with orderByKey(). Other type of values or using the version with 2 parameters is not supported
at com.google.firebase.database.Query.zza(Unknown Source)
at com.google.firebase.database.Query.zzb(Unknown Source)
at com.google.firebase.database.Query.endAt(Unknown Source)
at com.google.firebase.database.Query.endAt(Unknown Source)
at com.jimmytrivedi.lapitchat.ChatActivity.loadMoreMessages(ChatActivity.java:318)
这是我的代码：
private void loadMoreMessages() {
MessageReference = RootReference.child("Messages").child(currentUID).child(chatUser);
Query query = MessageReference.orderByKey().endAt(LastKey).limitToLast(10);
query.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages messages = dataSnapshot.getValue(Messages.class);
String messageKey = dataSnapshot.getKey();
if (PrevKey.equals(messageKey)) {
MsgList.add(itemPosition++, messages);
} else {
PrevKey = LastKey;
}
if (itemPosition == 1) {
LastKey = messageKey;
}
messageAdapter.notifyDataSetChanged();
refreshLayout.setRefreshing(false);
linearLayoutManager.scrollToPositionWithOffset(10, 0);
}
我不知道应该添加什么，因为在创建ChatFragment之前它运行良好，但是由于我做了一些更改并且我的片段为空白，所以我编写了wholw类，现在当我打开ChatFreagment并在ChatFragment中时，我重定向到ChatActivty，并且此异常即将到来。
ChatFragment.java
package com.priyanka.lapitchat;
import android.content.Context;
import android.content.Intent;
import android.graphics.Typeface;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.ChildEventListener;
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.Query;
import com.google.firebase.database.ValueEventListener;
import com.squareup.picasso.Picasso;
import de.hdodenhof.circleimageview.CircleImageView;
public class ChatFragment extends Fragment {
private RecyclerView ConversationList;
private DatabaseReference ConversationRef, MessageRef, UserRef;
private FirebaseAuth mAuth;
private String currentUID;
private View MainView;
public ChatFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
MainView = inflater.inflate(R.layout.fragment_chat, container, false);
ConversationList = MainView.findViewById(R.id.ConversationList);
mAuth = FirebaseAuth.getInstance();
currentUID = mAuth.getCurrentUser().getUid();
ConversationRef = FirebaseDatabase.getInstance().getReference().child("Chat").child(currentUID);
ConversationRef.keepSynced(true);
UserRef = FirebaseDatabase.getInstance().getReference().child("Users");
UserRef.keepSynced(true);
MessageRef = FirebaseDatabase.getInstance().getReference().child("Messages").child(currentUID);
LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
layoutManager.setReverseLayout(true);
layoutManager.setStackFromEnd(true);
ConversationList.setHasFixedSize(true);
ConversationList.setLayoutManager(layoutManager);
return MainView;
}
@Override
public void onStart() {
super.onStart();
Query conversationQuery = ConversationRef.orderByChild("timestamp");
Query query = FirebaseDatabase.getInstance()
.getReference()
.child("Chat")
.limitToLast(50);
FirebaseRecyclerOptions<Conversation> options = new FirebaseRecyclerOptions.Builder<Conversation>()
.setQuery(query, Conversation.class)
.build();
FirebaseRecyclerAdapter<Conversation, ConversationViewHolder> ConversationRecyclerViewAdapter = new
FirebaseRecyclerAdapter<Conversation, ConversationViewHolder>(options) {
@Override
protected void onBindViewHolder(@NonNull final ConversationViewHolder holder, int position, @NonNull final Conversation model) {
final String listUID = getRef(position).getKey();
Query lastMessageQuery = MessageRef.child(listUID).limitToLast(1);
lastMessageQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
String data = dataSnapshot.child("message").getValue().toString();
holder.setMassage(data, model.isSeen());
}
@Override
public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
UserRef.child(listUID).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
final String userName = dataSnapshot.child("Name").getValue().toString();
String userThumb = dataSnapshot.child("thumbImage").getValue().toString();
if (dataSnapshot.hasChild("Online")) {
String userOnline = dataSnapshot.child("Online").getValue().toString();
holder.setUserOnline(userOnline);
}
holder.setName(userName);
holder.setUserImage(userThumb, getContext());
holder.mView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(getContext(), ChatActivity.class);
intent.putExtra("userID", listUID);
intent.putExtra("userName", userName);
startActivity(intent);
}
});
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
@NonNull
@Override
public ConversationViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.users_single_layout, parent, false);
return new ConversationViewHolder(view);
}
};
ConversationList.setAdapter(ConversationRecyclerViewAdapter);
ConversationRecyclerViewAdapter.startListening();
}
public static class ConversationViewHolder extends RecyclerView.ViewHolder {
View mView;
public ConversationViewHolder(View itemView) {
super(itemView);
mView = itemView;
}
public void setMassage(String message, boolean isSeen) {
TextView userStatusView = mView.findViewById(R.id.userStatus);
userStatusView.setText(message);
if (!isSeen) {
userStatusView.setTypeface(userStatusView.getTypeface(), Typeface.BOLD);
} else {
userStatusView.setTypeface(userStatusView.getTypeface(), Typeface.NORMAL);
}
}
public void setUserOnline(String online) {
ImageView userOnlineView = mView.findViewById(R.id.online);
if (online.equals("true")) {
userOnlineView.setVisibility(View.VISIBLE);
} else {
userOnlineView.setVisibility(View.INVISIBLE);
}
}
public void setName(String userName) {
TextView userNameView = mView.findViewById(R.id.userName);
userNameView.setText(userName);
}
public void setUserImage(String userThumb, Context context) {
CircleImageView userImageView = mView.findViewById(R.id.userImage);
Picasso.get().load(userThumb).placeholder(R.drawable.defaultimage).into(userImageView);
}
}
}
LastKey是一个字符串，在下面的代码中的3个地方使用：
private void loadMoreMessages() {
MessageReference = RootReference.child("Messages").child(currentUID).child(chatUser);
Query query = MessageReference.orderByKey().endAt("LastKey").limitToLast(10);
query.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages messages = dataSnapshot.getValue(Messages.class);
String messageKey = dataSnapshot.getKey();
if (PrevKey.equals(messageKey)) {
MsgList.add(itemPosition++, messages);
} else {
PrevKey = LastKey;
}
if (itemPosition == 1) {
LastKey = messageKey;
}
messageAdapter.notifyDataSetChanged();
refreshLayout.setRefreshing(false);
linearLayoutManager.scrollToPositionWithOffset(10, 0);
}