Develop Reference

How do I read all the routeUp objects?

I want to read routeUp node`s all the objects.How can I read it?
This is the database :
enter image description here

To get all the object within your routeUp node, please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference routeRef = rootRef.child("route");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot dSnapshot : dataSnapshot.getChildren()) {
for(DataSnapshot ds : dSnapshot.child("routeUp").getChildren()) {
String haltName = ds.child("haltName").getValue(String.class);
Log.d(TAG, haltName);
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage());
}
};
routeRef.addListenerForSingleValueEvent(valueEventListener);
The output in your logcat will be:
Kaduwela
//an so on

Listener onDataChange Android Firebase

I want to make it store private string keyy, but it does not save, what happens? I tried it with textview if it shows the data.
DatabaseReference myRef = FirebaseDatabase.getInstance().getReference().child("Users").child("Customers");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot nodo : dataSnapshot.getChildren()) {
String key = nodo.getKey();
Log.d("TAG", key);
keyy = key;
mSetting.setText(key); // yes, show data
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
myRef.addListenerForSingleValueEvent(eventListener);
mSetting.setText(keyy); // No,show data

I hope this solve your problem
List<String> keyList = new ArrayList();
DatabaseReference myRef = FirebaseDatabase.getInstance().getReference().child("Users").child("Customers");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot nodo : dataSnapshot.getChildren()) {
String key = nodo.getKey();
keyList.add(key);
}
done(keyList);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
myRef.addListenerForSingleValueEvent(eventListener);
public void done(List k)
{
//show keys here
}

Do like this
List<String> keyList=new ArrayList<>();
DatabaseReference myRef = FirebaseDatabase.getInstance().getReference().child("Users").child("Customers");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot nodo : dataSnapshot.getChildren()) {
String key = nodo.getKey();
Log.d("TAG", key);
/*Add all the keys to keyList here*/
keyList.add(key);
}
/*After the loop ends set the list of keys to textview like this*/
if (keyList.size()>0)
{
for (String s : keyList)
{
mSetting.setText(mSetting.getText().toString()+"\n"+s);
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
myRef.addListenerForSingleValueEvent(eventListener);

Firebase Query get values

I have a list of Child-Data and wants to have a certain value.
My Firebase structure:
Now, I only have the Child "Text" and the currendUser "0zwtyRwgnogC8Qk91AtHj7amZb63"
So how can I get the values of "text and "user_id"?
My source code:
mDatabaseText = FirebaseDatabase.getInstance().getReference().child("Text");
query = mDatabaseText.startAt(mCurrentUser.getUid());
query.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot textSnapshot : dataSnapshot.getChildren()) {
/* String text = textSnapshot.getKey();
Toast.makeText(getActivity(), text, Toast.LENGTH_SHORT).show(); */
TextModel textModel = chatSnapshot.getValue(TextModel.class);
String t = textModel.getText();
Log.i("!!!!!!!text", t);
Toast.makeText(getActivity(), t, Toast.LENGTH_SHORT).show();
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
But this code doesn't work, why?
I used the query startAt.

Please use this code:
FirebaseDatabase rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference currentUserIdRef = rootRef.child("Text").child(currentUserId);
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String userId = (String) ds.getKey();
DatabaseReference userIdRef = rootRef.child("Text").child(currentUserId).child(userId);
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String user_id = (String) dataSnapshot.child("user_id").getValue();
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
};
userIdRef.addListenerForSingleValueEvent(eventListener);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
};
currentUserIdRef.addListenerForSingleValueEvent(eventListener);
In which currentUserId is the variable that you say you already have it.
Hope it helps.

Firebase query in query

I am trying to make multiple queries to my Firebase database, but it seems I am doing something wrong, and I just can't seem to understand what.
My code is this:
database = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = database.child("Tbl1");
Query tbl1Query = ref.orderByChild("type");
tbl1Query .addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
Tbl1Item item = singleSnapshot.getValue(Tbl1Item .class);
tbl1List.add(item);
}
DatabaseReference ref = database.child("Tbl2");
Query tbl2Query = ref.orderByChild("status");
tbl2Query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
tbl2Item item = singleSnapshot.getValue(tbl2Item.class);
tbl2List.add(item);
}
DatabaseReference ref = database.child("Tbl3");
Query tbl3Query = ref.orderByChild("status");
tbl3Query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
tbl3item item = singleSnapshot.getValue(tbl3item.class);
tbl3List.add(item);
}
SortTableData();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
The problem is that the app crashes though I get no error in console.
What I am trying to obtain, is create 3 lists of objects with data from table1, table2 and table3 and then call a method that will process that data.
If I remove the 2nd and 3rd queries, everything works fine, but I don't have all the needed data... so what I am doing wrong?

get Firebase nodes by children

If I have a database that is set up like so
-users
-uId0
-Name: "Bill"
-uId1
-Name: "Bob"
-uId2
-Name: "Dave"
How do I get the uId elements if there name child starts with B.
The query should return somthing like this?
-uId0
-Name: "Bill"
-uId1
-Name: "Bob"
Thanks!!

DatabaseReference myReference = FirebaseDatabase.getInstance().getReference();
myReference.child("users").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
//looping all your users
for (DataSnapshot messageSnapshot:dataSnapshot.getChildren())
{
name = (String)messageSnapshot.child("Name").getValue();
if (name.toLowerCase().contains("b")) {
//u can save your name with 'b' string here
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});

To achieve this, please use this code:
DatabaseReference usersRef = FirebaseDatabase.getInstance().getReference().child("users");
usersRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
String uId = (String) ds.getKey();
DatabaseReference uIdRef = FirebaseDatabase.getInstance().getReference().child("users").child(uId);
uIdRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String name = (String) dataSnapshot.child("Name").getValue();
if (name.matches("^[B].*$")) {
System.out.println(name);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
throw databaseError.toException(); // don't ignore errors
}
});