Develop Reference

I don't want the data registration in Firebase to be numbered Android

I do not want numbering to appear, I want the time to appear as written in the code, so what is the reason for such a problem to appear?
deviceModels.add(new DeviceModel(newDeviceName, newDeviceWat, newDeviceUse, currentDateAndTime));
FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance();
DatabaseReference databaseReference = firebaseDatabase.getReference();
databaseReference.child("DeviceInfo").child(currentUser).child(currentDateAndTime).addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot snapshot) {
// data base reference will sends data to firebase.
databaseReference.setValue(deviceModels);
Toast.makeText(MainActivity.this, "تم أضافة الجهاز", Toast.LENGTH_SHORT).show();
dialog.dismiss();
finish();
startActivity(getIntent());
}

It looks like your deviceModels is an array or a List, and this is how the Firebase Realtime Database persists arrays/lists. There is no way to configure it to do it differently, but you can of course use a different data type in your code.
More idiomatic in Firebase is to use the push() method when adding items to a list on the database. To learn more about why that is, have a look at Best Practices: Arrays in Firebase.
In your case you'd write the data for each individual DeviceModel:
databaseReference.push().setValue(new DeviceModel(newDeviceName, newDeviceWat, newDeviceUse, currentDateAndTime));
This will then end up in the database as:
DeviceInfo: {
"IN0r....T2": {
"-N.....": {
deviceId: ...,
deviceName: ...
}
}
}
And that entire list would then map back to a Map<String, DeviceModel> in your Java code.

Retrieve Data using Multiple keys Firebase Realtime Database

I have a list of Keys in a Array List . I want to retrieve data only from those keys but at a same time.
DatabaseReference mDBRef;
List<String> keys = new ArrayList<>();
I tried this with loop but the result coming in Model class is repeated 2 times.
for (int i= 0;i<keys.size();i++)
{
String id = keys.get(i);
Log.d("Keys",id);
mDBRef = FirebaseDatabase.getInstance().getReference().child("Gyms").child(id);
mDBRef.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(final DataSnapshot dataSnapshot) {
dataSnapshot.getKey();
gyms = dataSnapshot.getValue(Gyms.class);
if (gyms != null)
{
Log.d("Names",gyms.getName());
Toast.makeText(NearMeActivity.this, ""+ gyms.getName(), Toast.LENGTH_SHORT).show();
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}

The Firebase Realtime database doesn't support loading items based on an array of values. You'll have to load each item with a separate call.
While this may convolute your code, it is not nearly as slow as most developers think. This is because Firebase pipelines the requests. For a longer explanation of that, see my answer here: http://stackoverflow.com/questions/35931526/speed-up-fetching-posts-for-my-social-network-app-by-using-query-instead-of-obse/35932786#35932786

firebase real time database doesn't support multiple matches. You can see Firestore which is NoSQL and provide some flexibility.
See Firestore: https://firebase.google.com/docs/firestore/
You have to use custom search solution like Elastic Search.

Firebase and recyclerView

Hi I'm new in firebase and android studio and I have a problem
I want to store the data of this database in an array and next use the array to make a recycler view
Then in the main activity I wrote this:
And if I run the app only this is shown:
But if I do the same but instead of firebase i use a String[] with the data i want to show it works but i don't know why with firebase i can't.
if I change the references by this:
reference = database.getReference(FirebaseReferences.POKEMONS_REFERENCES);
reference.child(FirebaseReferences.APP_REFERENCES).addValueEventListener(new ValueEventListener() {
when I run the app, it automatically closes and i don't know what to do.
Could you please tell me what i'm doing wrong?
Thank you in advance.
Here is the logCat
https://github.com/adcasna/SearchViewPrueba2/wiki

Fisrts of all, please note that the Firebase documentation recommends against using arrays. Using an array is an anti-pattern when it comes to Firebase. One of the many reasons Firebase recommends against using arrays is that it makes the security rules impossible to write. If you still want to use this kind of structure, for getting those names and store them in an ArrayList, please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference appRef = rootRef.child("pokemons").child("app");
ValueEventListener eventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<String> list = new ArrayList<>();
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String c_name = ds.child("c_name").getValue(String.class);
list.add(c_name);
Log.d("TAG", c_name);
}
Log.d("TAG", list );
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
appRef.addListenerForSingleValueEvent(eventListener);

I can't get the key of firebase database

In my solution I save data from Windows form application. There is no problem. I can list them in my android app. On this point I am trying to get key value to update the data, but always I get null.
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference myReference = database.getReference();
Query myTopPostsQuery = myReference.child("DURUSLAR").orderByChild("kayitid").equalTo("1298843637");
myTopPostsQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot postSnapshot: dataSnapshot.getChildren())
{
//Childadi =postSnapshot.getKey().toString();
String anahtar=postSnapshot.getKey().toString();
Toast.makeText(getApplicationContext(),anahtar,Toast.LENGTH_LONG);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Can you please help me?

When you execute a query at a location in the Firebase Database, it will search for the property you order/filter on in each child under that location. Since you query in /DURUSLAR, Firebase looks for /DURUSLAR/{something}/kayitid. Such a property does not exist, since you only have /DURUSLAR/{something}/{pushid}/kayitid.
To fix this problem you have two options:
query at a lower level
query to the property at its (fixed) path
The first option is to create the query at a lower level in the tree:
Query myTopPostsQuery = myReference.child("DURUSLAR/K6").orderByChild("kayitid").equalTo("1298843637");
Now the query is looking for /DURUSLAR/{pushid}/kayitid and it will work.
The second option is to query for the known path of the property:
Query myTopPostsQuery = myReference.child("DURUSLAR").orderByChild("K6/-KknsAR4_KFAeZ1HVXPW/kayitid").equalTo("1298843637");
It seems unlikely you want this here, but the approach may be helpful in other situations. Often when you need this approach with push IDs in the path, you'll want to look at http://stackoverflow.com/questions/40656589/firebase-query-if-child-of-child-contains-a-value.

The reason you are getting null is because you are doing orderByChild on the wrong level of data . According to your data u need to have a child K4-> which has a unique_id_push_id -> kayitid.Therefore you need to traverse the K4 in order to get 1298843637 for key kayitid.You can follow this tutorial to understand the retrieving of data from firebase .
Query myTopPostsQuery = myReference.child("DURUSLAR").child("k6").orderByChild("kayitid").equalTo("1298843637");
myTopPostsQuery.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot postSnapshot: dataSnapshot.getChildren())
{
//Childadi =postSnapshot.getKey().toString();
String anahtar=postSnapshot.getKey().toString();
Toast.makeText(getApplicationContext(),anahtar,Toast.LENGTH_LONG);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});

FireBase Android Need 1 value saved under a single user

I have the following data structure on firebase for the user MF0qeRA4p7djfjgXxqwFOck3m6p02. I want to get the value of item3 to populate a single field into the User interface on an Android App. I have been looking through samples on Stackoverflow, but all I have found are outdated and do not work with the current version of firebase. I'm new to firebase completely and this is my first app on android. I've got the oncreate user method to populate the users email address and add the 4 item fields, but retrieving the data I'm completely lost and I am not sure where to even begin.
-Users
---MF0qeRA4p7djfjgXxqwFOck3m6p02
------item1:"1"
------item2:"2"
------item3:"3"
------item4:"4"

According to what I can identify is, you are facing problem retrieving data from this reference. Here is the code:
final DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("Users");
databaseReference.child("MF0qeRA4p7djfjgXxqwFOck3m6p02").addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Map<String, Object> map=(Map<String, Object>)dataSnapshot.getValue();
String item3=(String)map.get("item3");
display(item3);
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Hope this helps.

You can create a custom model and inside you can insert elements. Something like this:
public class Item {
private List<Object> ojects;
}
There you can save instance of Item on database. In this case you have more controll. Other case is to use push() method, that will generate a new encoded key, something like this:
mDatabase.child("items").push().put(new Object());