问题
I'm creating a social messaging app. the ideal on how the app function is where the messages are saved to the firebase database and then displayed on the RecyclerView.. the messages are saved to the database but not displayed on the RecyclerView.
please help...
thank you
message adopter class.
public class MessagesAdopter extends RecyclerView.Adapter {
public MessagesAdopter(List<Messages> messagesList) {
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
return null;
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
}
@Override
public int getItemCount() {
return 0;
}
public class MessageAdopter extends RecyclerView.Adapter<MessageAdopter.MessageViewHolder> {
private List<Messages> usersmessengeslist;
private FirebaseAuth mAuth;
private DatabaseReference userdatabaseref;
public MessageAdopter (List<Messages> usersmessengeslist){
this.usersmessengeslist = usersmessengeslist;
}
public class MessageViewHolder extends RecyclerView.ViewHolder {
private TextView sender_typed_message,reciever_typed_message;
CircleImageView reciever_image_view;
public MessageViewHolder(@NonNull View itemView) {
super(itemView);
sender_typed_message = itemView.findViewById(R.id.sender_typed_message);
reciever_typed_message = itemView.findViewById(R.id.reciever_typed_message);
reciever_image_view = itemView.findViewById(R.id.reciver_profile_image);
}
}
@NonNull
@Override
public MessageViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View V = LayoutInflater.from(parent.getContext())
.inflate(R.layout.users_message_layout,parent ,false);
mAuth = FirebaseAuth.getInstance();
return new MessageViewHolder(V);
}
@Override
public void onBindViewHolder(@NonNull final MessageViewHolder holder, int position) {
String messagesenderid = mAuth.getCurrentUser().getUid();
Messages messages = usersmessengeslist.get(position);
String fromUserID = messages.getFrom();
String frommessagetype = messages.getType();
userdatabaseref = FirebaseDatabase.getInstance().getReference().child("Users").child(fromUserID);
userdatabaseref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()){
String image = dataSnapshot.child("profileimage").getValue(String.class);
Picasso.get().load(image).placeholder(R.drawable.profile).into(holder.reciever_image_view);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
if (frommessagetype.equals("text")){
holder.reciever_image_view.setVisibility(View.INVISIBLE);
holder.reciever_typed_message.setVisibility(View.INVISIBLE);
if (fromUserID.equals(messagesenderid)){
holder.sender_typed_message.setBackgroundResource(R.drawable.sender_message_background);
holder.sender_typed_message.setTextColor(Color.WHITE);
holder.sender_typed_message.setGravity(Gravity.LEFT);
holder.sender_typed_message.setText(messages.getMessage());
}
else
{
holder.sender_typed_message.setVisibility(View.INVISIBLE);
holder.reciever_typed_message.setVisibility(View.VISIBLE);
holder.reciever_image_view.setVisibility(View.VISIBLE);
holder.reciever_typed_message.setBackgroundResource(R.drawable.reciever_message_background);
holder.reciever_typed_message.setTextColor(Color.WHITE);
holder.reciever_typed_message.setGravity(Gravity.LEFT);
holder.reciever_typed_message.setText(messages.getMessage());
}
}
}
@Override
public int getItemCount() {
return usersmessengeslist.size();
}
}
}
chat activity:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);
mAuth = FirebaseAuth.getInstance();
messagesenderuserIdD = mAuth.getCurrentUser().getUid();
RootRef = FirebaseDatabase.getInstance().getReference();
recievereruserid = getIntent().getExtras().get("visit_user_id").toString();
recieverrusername = getIntent().getExtras().get("userName").toString();
iniitializefeildz();
displayrecieveruserinformtion();
sendmessagebutton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sendusermessage();
}
});
fetchmessage();
}
private void fetchmessage() {
RootRef.child("Messages").child(messagesenderuserIdD).child(recievereruserid)
.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages messages = dataSnapshot.getValue(Messages.class);
mMessagesList.add(messages);
MessagesAdopter.notifyDataSetChanged();
}
@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) {
}
});
}
private void sendusermessage() {
String messagetext = user_inout_message.getText().toString();
if (TextUtils.isEmpty(messagetext)){
Toast.makeText(chatActivity.this,"please type a message",Toast.LENGTH_SHORT).show();
}
else {
String message_sender_ref = "Messages/" + messagesenderuserIdD + "/" + recievereruserid;
String message_reciever_ref = "Messages/" + recievereruserid + "/" + messagesenderuserIdD;
DatabaseReference user_message_key = RootRef.child("Message").child(messagesenderuserIdD).child(recievereruserid).push();
String message_push_id =user_message_key.getKey();
Calendar callforddate = Calendar.getInstance();
SimpleDateFormat currentdate =new SimpleDateFormat("dd-MMMM-yyyy");
savecurrentdate= currentdate.format(callforddate.getTime());
Calendar calFordTime = Calendar.getInstance();
SimpleDateFormat currentTime = new SimpleDateFormat("HH:mm");
savecurrenttime = currentTime.format(callforddate.getTime());
Map messageTextbody = new HashMap();
messageTextbody.put("Message", messagetext);
messageTextbody.put("time", savecurrenttime);
messageTextbody.put("date", savecurrentdate);
messageTextbody.put("type", "text");
messageTextbody.put("from", messagesenderuserIdD);
Map messageBodyDetails = new HashMap();
messageBodyDetails.put(message_sender_ref + "/"+ message_push_id,messageTextbody);
messageBodyDetails.put(message_reciever_ref + "/"+ message_push_id,messageTextbody);
RootRef.updateChildren(messageBodyDetails).addOnCompleteListener(new OnCompleteListener() {
@Override
public void onComplete(@NonNull Task task) {
if (task.isSuccessful()){
Toast.makeText(chatActivity.this,"message sent successfully",Toast.LENGTH_SHORT).show();
user_inout_message.setText("");
}
else {
String message = task.getException().getMessage();
Toast.makeText(chatActivity.this,"Error" + message,Toast.LENGTH_SHORT).show();
user_inout_message.setText("");
}
}
});
}
}
private void displayrecieveruserinformtion() {
chat_username.setText(recieverrusername);
RootRef.child("Users").child(recievereruserid).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()){
final String profileimage = dataSnapshot.child("profileimage").getValue(String.class);
Picasso.get().load(profileimage).placeholder(R.drawable.profile).into(chat_circular_imageview);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
private void iniitializefeildz() {
mToolbar = findViewById(R.id.action_cjat_bar);
setSupportActionBar(mToolbar);
ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setDisplayShowCustomEnabled(true);
LayoutInflater layoutInflater= (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View action_bar_view = layoutInflater.inflate(R.layout.chat_custom_appbar,null);
actionBar.setCustomView(action_bar_view);
chat_username = findViewById(R.id.user_chat_displayname);
chat_circular_imageview = findViewById(R.id.user_chat_displayimage);
user_inout_message= findViewById(R.id.chat_write_message_here);
sendmessagebutton = findViewById(R.id.send_chat_message);
sendimagemessage = findViewById(R.id.chat_chooseimage);
MessagesAdopter = new MessagesAdopter(mMessagesList);
messagesview = findViewById(R.id.messageview_list);
linearlayoutmanager = new LinearLayoutManager(this);
messagesview.setHasFixedSize(true);
messagesview.setLayoutManager(linearlayoutmanager);
messagesview.setAdapter(MessagesAdopter);
}
}
回答1:
hi i am fatching my massages from firebase database with this, try this it will help you :-
private void readMessage(final String myId, final String userId) {
mChat = new ArrayList<>();
reference = FirebaseDatabase.getInstance().getReference(chatTableName);
try {
reference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
mChat.clear();
Chat chat = null;
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
chat = snapshot.getValue(Chat.class);
assert chat != null;
if (chat.getReceiver().equals(myId) && chat.getSender().equals(userId) ||
chat.getReceiver().equals(userId) && chat.getSender().equals(myId)) {
mChat.add(chat);
}
adapter = new MessageAdapter(UserMessageActivity.this, mChat);
recyclerView.setAdapter(adapter);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
} catch (Exception e) {
Toast.makeText(this, "" + e.getMessage(), Toast.LENGTH_SHORT).show();
}
}
来源：https://stackoverflow.com/questions/55456949/displaying-messages-from-firebase-database