We Keep Coding

Check value of child in Firebase DB Java

I am trying to select data from my database and I want to check if a specific child node has a one or a zero as it's value. If it has a 1 then I don't want to show info from that specific user. If it has a zero then I want to show info from that specific user.
I did it in a method above the one I'm working on(I followed this answer How to get child of child value from firebase in android?) and I got it working no problem. But I can't do the same for my other method and I have been trying all day now.
As of right now, the only result I am getting is the list not showing up at all. Can someone please help me ?
Method that works:
private void getPosts() {
followingList = new ArrayList<>();
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Video_Posts");
FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
reference.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
myPosts.clear();
//followingList.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
Post post = snapshot.getValue(Post.class);
if (followingList.isEmpty()) {
if (!post.getPublisher().equals(firebaseUser.getUid())) {
DatabaseReference zonesRef = FirebaseDatabase.getInstance().getReference("Users");
DatabaseReference zone1Ref = zonesRef.child(post.getPublisher());
DatabaseReference zone1NameRef = zone1Ref.child("acc_closed");
zone1NameRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//Log.i(TAG, dataSnapshot.getValue(String.class));
if (dataSnapshot.getValue(String.class).equals("1")) {
//Toast.makeText(getContext(), "Account closed", Toast.LENGTH_SHORT).show();
} else if (dataSnapshot.getValue(String.class).equals("0")) {
//Toast.makeText(getContext(), "Not closed.", Toast.LENGTH_SHORT).show();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
Query query = rootRef
.child("Follow")
.child(firebaseUser.getUid())
.child("following")
.child(post.getPublisher());
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
//Do something
Toast.makeText(getContext(), "Following.", Toast.LENGTH_SHORT).show();
} else {
//Do something else
myPosts.add(post);
Collections.shuffle(myPosts);
//Toast.makeText(getContext(), "Something.", Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
};
query.addListenerForSingleValueEvent(valueEventListener);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
//Log.w(TAG, "onCancelled", databaseError.toException());
}
});
} else if (myPosts == null) {
Toast.makeText(getContext(), "Nothing.", Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(getContext(), "List is not empty.", Toast.LENGTH_SHORT).show();
for (String id : followingList) {
assert post != null;
if (!post.getPublisher().equals(id)) {
myPosts.add(post);
Toast.makeText(getContext(), "Something.", Toast.LENGTH_SHORT).show();
} else if (myPosts == null) {
Toast.makeText(getContext(), "Nothing.", Toast.LENGTH_SHORT).show();
}
}
}
}
adapterExplorer.notifyDataSetChanged();
progressBar.setVisibility(View.GONE);
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
}
});
}
Method that doesn't work:
private void searchUsers(String s) {
Query query = FirebaseDatabase.getInstance().getReference("Users");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (search_bar.getText().toString().equals("")) {
recyclerView.setVisibility(View.INVISIBLE);
}
mUsers.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
User user = snapshot.getValue(User.class);
DatabaseReference zonesRef = FirebaseDatabase.getInstance().getReference("Users");
DatabaseReference zone1Ref = zonesRef.child(user.getId());
DatabaseReference zone1NameRef = zone1Ref.child(user.getAcc_closed());
//mUsers.add(user);
zone1NameRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapS) {
if (snapS.getKey().equals("1")) {
} else if (snapS.getKey().equals("0")){
//if (!snapS.exists()) {
Log.d("TAG", snapS.toString());
mUsers.add(user);
//}
}
//}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
Log.d("Error name", error.getMessage());
}
});
}
userAdapter.notifyDataSetChanged();
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
Log.d("Error name", error.getMessage());
}
});
}
Database:
"Users": {
"4mFQt8Lf3CTNrQF74sy8wwyFoLh1": {
"acc_closed": "0",
"bio": "",
"dateAdded": "19-06-2022 17:28:56",
"date_time": 1655674136805,
"device_token": "feGjHNzaR7S8yaV2HKg0rt:APA91bEXAiYwT52niHVxR2ENrcaKXSNs11Z5ss-g2gsDwTs4wbjqjcrN4ZUmemqiMzp6SZM6UXD5TFrc1JND_DoEgd-Ni9wMeCa73EzvKBAaj5aXJf1GjgjSsTVwBg1A6VvhvVwF1VSX",
"fullname": "Brandon",
"id": "4mFQt8Lf3CTNrQF74sy8wwyFoLh1",
"imageurl": "https://firebasestorage.googleapis.com/v0/b/gone-b14f5.appspot.com/o/default.jpg?alt=media&token=befece91-9248-45ee-ab6f-b1b3d217c6b4",
"username": "bran1",
"verified": "false"
},
EDIT:
The code above (searchUsers) kind of works. When I put text into the search bar nothing shows up. But when I hit the back button and remove the keyboard the data shows up. It's like I'm actually waiting for data to change.

The simple fix is that you should call notifyDataSetChanged after you modified the data that the adapter shows, where right now you're calling it before that.
So move the call to userAdapter.notifyDataSetChanged() to right after mUsers.add(user):
Query query = FirebaseDatabase.getInstance().getReference("Users");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (search_bar.getText().toString().equals("")) {
recyclerView.setVisibility(View.INVISIBLE);
}
mUsers.clear();
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
User user = snapshot.getValue(User.class);
DatabaseReference zonesRef = FirebaseDatabase.getInstance().getReference("Users");
DatabaseReference zone1Ref = zonesRef.child(user.getId());
DatabaseReference zone1NameRef = zone1Ref.child(user.getAcc_closed());
zone1NameRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapS) {
if (snapS.getKey().equals("1")) {
} else if (snapS.getKey().equals("0")){
Log.d("TAG", snapS.toString());
mUsers.add(user);
userAdapter.notifyDataSetChanged(); // 👈
}
}
#Override
public void onCancelled(#NonNull DatabaseError error) {
Log.d("Error name", error.getMessage());
}
});
}
}
There is some more (but not related to the problem) room for optimization here, as the dataSnapshot you get in the outermost listener already contains the data for *alldata under/Users`.
So there's no need to add an other listener to get the acc_closed value for each user. Instead you can just navigate the initial snapshot like this:
Query query = FirebaseDatabase.getInstance().getReference("Users");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (search_bar.getText().toString().equals("")) {
recyclerView.setVisibility(View.INVISIBLE);
}
mUsers.clear();
for (DataSnapshot userSnapshot : dataSnapshot.getChildren()) {
DataSnapshot snapS = userSnapshot.child("acc_closed");
String accClose = snapS.getValue(String.class)
if (accClose.equals("0")){
Log.d("TAG", accClose);
mUsers.add(userSnapshot.getValue(User.class));
userAdapter.notifyDataSetChanged();
}
}
}
Finally: your code retrieves all /Users to then only use the users who have acc_close being equal to "0". This wastes (your and your user's) bandwidth, especially as you're adding more users. It's much better to use a query to retrieve only the necessary data from the server/database:
DatabaseReference usersRef = FirebaseDatabase.getInstance().getReference("Users");
Query query = usersRef.orderByChild("acc_closed").equalTo("0");
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
if (search_bar.getText().toString().equals("")) {
recyclerView.setVisibility(View.INVISIBLE);
}
mUsers.clear();
for (DataSnapshot userSnapshot : dataSnapshot.getChildren()) {
mUsers.add(userSnapshot.getValue(User.class));
}
userAdapter.notifyDataSetChanged();
}

How to check for a specific value exist in the firebase realtime database?

I am trying to write a query to check if there is any "Pending" status on mcustDeliveryStatus. I want to check in Order node that is there any Pending status for mcustDeliveryStatus.
I wrote the following query
mDatabase = FirebaseDatabase.getInstance().getReference("Order");
final Query query = mDatabase.OrderByChild("mcustDeliveryStatus").equalTo("Pending");
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
Toast.makeText(VWelcome.this, "new order", Toast.LENGTH_LONG).show();
Intent i = new Intent(VWelcome.this, ViewOrderRequest.class);
startActivity(i);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
This query works fine but the problem is intent runs even when there is no Pending status in my Order node. Anyone knows why?

Since you annotate your DataSnapshot object with #NonNull, it means that you tell the compiler that your object cannot be null, so it will always return something. With other words, if there are no results, it will return an empty DataSnapshot object. To solve this, you should check how many children are inside that object using the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference orderRef = rootRef.child("Order");
Query query = orderRef.orderByChild("mcustDeliveryStatus").equalTo("Pending");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
long count = dataSnapshot.getChildrenCount();
if (count > 0) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String mGasBand = ds.child("mGasBand").getValue(String.class);
Log.d(TAG, mGasBand);
}
} else {
Log.d(TAG, "No data!");
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
query.addListenerForSingleValueEvent(valueEventListener);

SingleValueEventListener do not get the value after button click

I need to get nickname value from Firebase Real time database after button is clicked. So i made singleValueListner() in button´s onClick method. But it don´t work.
I have tried debug it, but code didn´t get into singleValueEventListener()
Button getName = (Button)findViewById(R.id.getName);
getName.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
DatabaseReference db = FirebaseDatabase.getInstance().getReference().child("Member").child(user.getUid());
db.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot data : dataSnapshot.getChildren()) {
TextView tv = (TextView)findViewById(R.id.tv);
tv.setText(data.child("nickname").getValue().toString());
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
}
});
Database JSON structure:
{
"Member" : {
"1Zuv6VZZ0kPluwc33f1QQQ7DZD93" /* UID */ : {
"-LgIHwiAjfuh5pjK7wzl" : {
"actualScore" : 0,
"bestScore" : 0,
"email" : "some#email.com",
"nickname" : "Vitek",
"season" : 0
}
}
}
}
Database structure:
https://drive.google.com/file/d/15B4b6Rb_WAiS6fioI9gItyijrbDiVjzJ/view
I need to get nickname, I think this is writen good, but not. So, what is wrong?

To get the value of your nickname property, please use the following lines of code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("Member").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String nickname = dataSnapshot.child("nickname").getValue(String.class);
Log.d(TAG, nickname);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
The output in your logcat will be:
Vitek
So there is no need to loop through the DataSnapshot object in order to get the value of your nickname property. If you don't get this result, please check the logcat to see if you have an error message printed out.

You are only referring up to user's id but there is also a parent key of user detail which you need to reference.
tv.setText(data.child("LgiH------").child("nickname").getValue().toString());
but try to remove that second key from your registering user's code because it is not helpful.

You have made a mistake in refering your firebase root node. just change your line as below :
DatabaseReference db = FirebaseDatabase.getInstance().getReference("Member");
Now,just call your singlevalue event.
db.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot data : dataSnapshot.getChildren()) {
TextView tv = (TextView)findViewById(R.id.tv);
tv.setText(data.child("nickname").getValue().toString());
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
This will do your stuff. try debugging your code with log at step by step.

How to retrieve value from firebase without getting the unique key

I am trying to retrieve an url from Firebase in Android. However, my problem is that I can't retrieve the url without also getting the unique key of the child.
The value I am trying to retrieve is the following:
Down below is the code I use to retrieve the data from firebase.
final FirebaseDatabase database = FirebaseDatabase.getInstance();
myRef = database.getReference().child("LoadItems");
myRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot child : dataSnapshot.getChildren() ){
String key;
key = child.getKey();
Log.d(TAG, "onDataChange: " + key);
Log.d(TAG, "onDataChange: " + child.getValue());
}
}
#Override
public void onCancelled(DatabaseError databaseError) { }
});
So what I am trying to get is what the url alone.

There is no need to know any key in order to get that URL. So please use the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference shoesRef = rootRef.child("LoadItems").child("Shoes");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String url = ds.getValue(String.class);
Log.d(TAG, url);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
shoesRef.addListenerForSingleValueEvent(valueEventListener);

Firebase listener not getting called

I want to check whether node is created or not. I just implemented below called with Toast but nothing toasting at all.
note: firebase DataBase is Total null now
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
reference.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Toast.makeText(RegisterActivity.this, dataSnapshot.getKey() + "", Toast.LENGTH_SHORT).show();
}
#Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText(RegisterActivity.this, databaseError.toString() + "", Toast.LENGTH_SHORT).show();
}
});
secondly below code i tried but no luck
DatabaseReference reference = FirebaseDatabase.getInstance().getReference();
reference.child("device_id");
reference.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Toast.makeText(RegisterActivity.this, dataSnapshot.getKey() + "", Toast.LENGTH_SHORT).show();
}
#Override
public void onCancelled(DatabaseError databaseError) {
Toast.makeText(RegisterActivity.this, databaseError.toString() + "", Toast.LENGTH_SHORT).show();
}
});

Change this line of code:
reference.addListenerForSingleValueEvent(new ValueEventListener() {
with:
reference.child("device_id").addListenerForSingleValueEvent(new ValueEventListener() {