Develop Reference

It does not fetch the required value Firebase Android

It does not fetch the required value and writes null What is wrong with the code please help
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = rootRef.child("analysis_Client").child(searchUserId);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
userTotal = ds.child("Total").getValue(String.class);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
//Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
A picture of the firebase of the way to list the data I want to call both(Total - Rest - ProductNum)

How to get the names of the json columns from firebase? I leave an example below my question

I would like to list the names of the dates, such as 24_1_2020, 25_1_2020, etc ...

Assuming that teLm ... IWV2 is the uid of the authenticated user, to display only those keys 24_1_2020, 25_1_2020, please use the following lines of code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("Mensaje").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String key = ds.getKey();
Log.d(TAG, key);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
See, I have used the getChildren() method to loop through the DataSnapshot object, which basically contains all children under the uid node. Calling getKey(), you can get each key that is corresponding to each child.
If teLm ... IWV2 is not the uid of the authenticated user, then simply add that String directly in your reference:
DatabaseReference uidRef = rootRef.child("Mensaje").child("teLm ... IWV2");

How to get data of a child in Firebase

I have my database tree structure like this:
Please tell me how do I get the value of "username" if I have the value of "userid"

how do I get the value of "username" if I have the value of "userid"
To solve this, please use the following lines of code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("users").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String username = dataSnapshot.child("username").getValue(String.class);
Log.d(TAG, username);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
The output in the logcat will be:
hisoka

How to fetch child names in Firebase realtime database

This is my Firebase database. I want to fetch only the child names of Intake-Sec like CSE, EEE. Not the children of CSE or EEE. How can I do this?
Thanks in advance!

To get only the CSE and EEE, please use the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<String> list = new ArrayList<>();
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String key = ds.getKey();
list.add(key);
Log.d(TAG, key);
}
//Do what you need to do with your list
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
rootRef.addListenerForSingleValueEvent(valueEventListener);
The list will contains only two elements as it will also be printed in the logcat:
CSE
EEE

Retrieve all data from Firebase Database

ANDROID: I have a Firebase database like this.
In my app, I would like to compile an arraylist that displays all values from the nameofEntry [DESCRIBED BELOW]. By this I mean the "balso," the "nairboh" and so on.
I have the references:
DatabaseReference root = FirebaseDatabase.getInstance().getReference();
DatabaseReference users = root.child("Users");
DatabaseReference childRef = users.child(userID);
DatabaseReference childRefNameNode = childRef.child(nameOfEntry);
childRefNameNode.child(nameOfEntry).setValue(nameOfEntry);
//FETCH DATA
childRefNameNode.child(nameOfEntry).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String valueFromDB = dataSnapshot.getValue(String.class);
Log.i("Jimit", valueFromDB);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
But this only fetches for one entry. How can I get more entries? [All of them]?

You need to use this code snippet. You haven't used any for loop to step over your children.
EDIT: Also, update your database reference as:
//Updated ref
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Users").child(userID);*
//add listener to updated ref
ref.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//use the for loop here to step over each child and retrieve data
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()){
String valueFromDB = childSnapshot.getValue(String.class);
Log.i("Jimit", valueFromDB);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Do let me know if it changes anything for you.