I'm calling addValueEventListener inside the button click, but this method only reads the last item in the node. I want to read all the child value in the node What went wrong here?
btnorder.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
databaseReference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for(DataSnapshot dataSnapshot1:dataSnapshot.getChildren())
{
SelectedItems si=dataSnapshot1.getValue(SelectedItems.class);
si.getItemname();
Toast.makeText(MyBookedItems.this, ""+si.getItemname(), Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
});
I think you can create an array list and put all snapshot data into it, and then you can find the last data of the list with the value you find by subtracting one from the length of the list. Sorry for my bad English :( I have tried to explain in the solution in the code below)
ArrayList<SelectedItems> selectedItems = new ArrayList<SelectedItems>();
for(DataSnapshot dataSnapshot1:dataSnapshot.getChildren())
{
SelectedItems si=dataSnapshot1.getValue(SelectedItems.class);
selectedItems.add(si);
}
selectedItems.get(selectedItems.size());
It's read all the values but I got the output as a Toast message, because of that I only see the last value)
Related
I have a very simple code:
// get users poll date, and set in relevant text view
Query query = gameRef.child("users_loto").child("zaalkIb4W0V7MGbekLhqjP34IQi1").orderByChild("pollRank").limitToLast(1);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
nDate = Long.parseLong(ds.child("pollRank").getValue().toString().substring(0, 14));
user_result.setText(String.valueOf(nDate));
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
};
query.addListenerForSingleValueEvent(valueEventListener);
I ordered it by pollRank - it is the same number as the child name.
It seems to return the last value of the relevant node:
But instead, it always returns the one before :
A very weird behavior...
Any thoughts about why it happens?
Tnx for #ShehanWisumperuma!
gameRef.keepSynced(true) was the correct answer to my issue!!!
Tnx for all of you who tried to help me!
My Firebase Realtime Database has been built by loading an object of the Java class HashMap. In my Android Studio app I'm trying to write a method that takes a String (the key) as input, searches through the database and if the string is found it returns the associated Float (the value), otherwise it returns 0. How can I do this? Any help would be really appreciated!
EDIT: I've tried to follow the suggestions, adapting them to my particular case, but I didn't manage to solve the problem yet.
I wrote the following code in MainActivity:
DatabaseReference myRef;
Float tempValue;
#Override
protected void onCreate(Bundle savedInstanceState) {
...
myRef = FirebaseDatabase.getInstance().getReference("myRoot");
tempValue=0f;
...
}
public void retrieveValueFromDatabase(String childName, final MainActivity activity){
myRef.child(childName).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Float value=dataSnapshot.getValue(Float.class);
if (value==null){
value=0f;
}
activity.tempValue=value;
//First Toast
//Toast.makeText(activity,"tempValue = "+tempValue.toString(), Toast.LENGTH_LONG).show();
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException();
}
});
}
public void useValues(){
retrieveValueFromDatabase(childName,this);
//Second Toast
//Toast.makeText(this,"tempValue = "+tempValue.toString(), Toast.LENGTH_LONG).show();
//code using tempValue from here
...
}
If I uncomment the first toast, the correct value inside tempValue is shown, but if I uncomment the second toast, the value of tempValue shown is the default one (0.0). What am I missing?
You need to use addValueEventListener to retrieve data from the database:
DatabaseReference ref = FirebaseDatabase.getInstance().getReference("myRoot").orderByChild("name").equalTo("peter");
ref.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Log.i("Database", dataSnapshot.child("floatValue").getValue(Long.class));
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException();
}
})
Here, you add a reference to the root node, then query using equalTo() to check if name = peter exists in the database and return the float value.
You should read the guide:
https://firebase.google.com/docs/database/android/read-and-write
I am trying to make it so that when a user creates an open game, in my Firebase Database the name of the game is the size of the list. So the very first game created the name of it will = 0, and if another user creates a game then the game will be labeled 1 and so on.
I have it set up right now so that the games are labeled the size of the game list, but the list isn't really updating. The games keep getting called '0' because it thinks the list is empty even though I have visual confirmation in the app that there are items being added to the list.
So my question is: How can I make it so the list continuously updates each time a game is added, and how can I make it so that it updates for all users and not just the user who created the game?
This is what I have setup right now. Here are the variables I am using for the list and the integer getting the list size
ArrayList<String> openGames = new ArrayList<>();
int gameSlot = openGames.size();
Here is what I use to name the game when it is created.
gameMaker = new GameMaker(hp.uid, userName, wagerD, gameSlot);
FirebaseDatabase.getInstance().getReference("FCGames").child(Integer.toString(gameSlot))
.setValue(gameMaker).addOnCompleteListener...
And this is what I have to add the game to the list.
cgRef.child(Integer.toString(gameSlot)).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
openGames.add(userName);
adapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
So again my question is how can I make this list update correctly and how can I make it update for all users on the app?
Edit
Here is what I did with my onChangeData
cgRef.child(Integer.toString(gameSlot)).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
wager = (String) dataSnapshot.child("wager").getValue();
gameSlot = openGames.size();
adapter.notifyDataSetChanged();
}
and now the openGames.add is in my createGameLobby method.
FirebaseDatabase.getInstance().getReference("FCGames").child(Integer.toString(gameSlot))
.setValue(gameMaker).addOnCompleteListener(new OnCompleteListener<Void>() {
#Override
public void onComplete(#NonNull Task<Void> task) {
if (task.isSuccessful()) {
openGames.add(userName);
Toast.makeText(FlipCoinLobby.this, "Game creation successful.", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(FlipCoinLobby.this, task.getException().getMessage(), Toast.LENGTH_SHORT).show();
}
}
});
^^ that is just the important snippit from the method. And then I have an onClickListener that creates that calls that method when a button is pressed
In below code segment, you did that openGames.add(username) in onDataChange listener. I think it is an incorrect use of this ondatachange function
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
openGames.add(userName);
adapter.notifyDataSetChanged();
}
please use this to get data from db and update your data. Then push your data to db. You didn't use snapshot value also. You can get most recently updated data from dataSnapshot . Use it to update user data then push it to db
I have a Firebase database that I want to retrieve the friend ID from. This works perfectly as I'm getting the right value when logging the friendUserId in the for loop. However, the log at the end of the method only displays the right value after executing the method twice. At first it displays "s", the second time it displays the string that I want. I feel like it has got something to do with processing time of the query, but I'm not sure really. How do I solve this?
public String friendUserId="s";
public void checkUserExistence() {
mDatabase.child("Users")
.orderByChild("username")
.equalTo(EmailSearchQuery)
.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
friendUserId = childSnapshot.getKey();
Log.d("dwada",friendUserId);
}
} else
Toast.makeText(AddAFriend.this, "Gebruiker niet gevonden", Toast.LENGTH_LONG);
}
#Override
public void onCancelled(DatabaseError firebaseError) {
Log.e("MainActivity", "onCancelled", firebaseError.toException());
}
});
Log.d("dwada",friendUserId);
}
for example searching in circles for a user circle if a data exist I want it DO process 1 and if data doesn't exist I want it to create one then DO process 2 ... but what happens in this code if data doesn't exist it will create one then do process 2 then go back then do process 1 after checking. so how can I stop the listener after process 2.
sorry if the circles example is too ambiguous but this is the simplest example I could think of .
Firebase ref= new Firebase("https://XXXXX.firebaseio.com/circles/");
Query queryRef = ref.orderByChild("circalename").equalTo(user.circalename);
ValueEventListener listener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot datasnapshot) {
if (datasnapshot.exists()) { // I don't want to get back here after
//creating the data in the else statement
// DO process 1
}
// if my data doesnt exist I will create one after that STOP listening
else {
// create circle
// do process 2
}
}
What you can do is use addListenerForSingleValueEvent
as it listens to the event only once
i.e. in your case
queryRef.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot)
{
if (datasnapshot.exists()) {
// code if data exists
} else {
// code if data does not exists
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Despite Shubham Arora's answer is the best solution for this case, I'm going to show you how to do exactly what you asked with these two solutions that are quite simple:
1. Global boolean
Create a global boolean and change it once your condition is met:
query.addListenerForSingleValueEvent(new ValueEventListener() {
boolean processDone = false;
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists() && !processDone) {
// do process 1
} else {
// do process 2
processDone = true;
}
}
#Override public void onCancelled(DatabaseError databaseError) {}
});
2. Remove listener
Remove your listener once your condition is met:
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
// do process 1
} else {
// do process 2
query.removeEventListener(this);
}
}
#Override public void onCancelled(DatabaseError databaseError) {}
});
Both solutions did work fine for me when I was using ChildEventListener and Shubham Arora's answer couldn't help.