how to get all child list from Firebase android

Question

I want all child list from Firebase in android   I have implement this code but its not working   mFirebaseRef   new Firebase FIREBASE URL    mFirebaseRef addValueEventListener new ValueEventListener          Override     public void onDataChange DataSnapshot dataSnapshot            List lt String gt  td    ArrayList lt String gt   dataSnapshot getValue              notifyDataSetChanged                Override     public void onCancelled FirebaseError firebaseError

User · Answer

your problem is why your code doesn t work   this your code    Firebase ref   new Firebase FIREBASE URL      ref addValueEventListener new ValueEventListener            Override       public void onDataChange DataSnapshot snapshot              Log e  Count       snapshot getChildrenCount               for  DataSnapshot postSnapshot  snapshot getChildren                   lt YourClass gt  post   postSnapshot getValue  lt YourClass gt  class               Log e  Get Data   post  lt YourMethod gt                                 Override       public void onCancelled FirebaseError firebaseError              Log e  The read failed     firebaseError getMessage                     you miss the simplest thing  getChildren        FirebaseDatabase db   FirebaseDatabase getInstance    DatabaseReference reference   FirebaseAuth getInstance   getReference  Donald Trump     reference addValueEventListener new ValueEventListener         Override    public void onDataChange DataSnapshot dataSnapshot                 int count    int  dataSnapshot getChildrenCount       retrieve number of childrens under Donald Trump              String   hairColors   new String count                index   0              for  DataSnapshot datas   dataSnapshot getChildren                      hairColors index    datas getValue String class                              index                 for  int i   0  i  lt  count  i                Toast MainActivity this   hairColors       hairColors i   toast LENGTH SHORT  show                                    Override         public void onCancelled DatabaseError databaseError

User · Answer

ArrayList lt String gt  keyList   new ArrayList lt String gt     mKeyRef addValueEventListener new ValueEventListener              Override         public void onDataChange DataSnapshot dataSnapshot                for  DataSnapshot childDataSnapshot   dataSnapshot getChildren                      String temp   childDataSnapshot getKey                    keyList add temp                   i   keyList size                                      Override         public void onCancelled DatabaseError databaseError                throw databaseError toException                        This code is working fine to add all firebase key into arraylist  you can do it with firebase values  of other static values

User · Answer

Override        public void onDataChange DataSnapshot dataSnapshot               for  DataSnapshot postSnapshot   dataSnapshot getChildren                     User user   postSnapshot getValue User class                  list add user                           for  int i 0 i lt list size   i                                Log e  Name  list get i  getname                    Log e  Phone  list get i  getphone                                    Override        public void onCancelled FirebaseError firebaseError           Log e  error  firebaseError getMessage                       Class model  class User   String name   String phone   public String getname         return name     public void setname String name        this name   name      public String getphone         return phone     public void setphone String phone        this phone   phone        List binding  List lt User gt  list  new ArrayList  lt  gt       this work for you

User · Answer

You Need to write a custom Deserializer and then loop it and get the values of the hasmap   Custom Deserializer -  public class UserDetailsDeserializer implements JsonDeserializer lt AllUserDetailsKeyModel gt             bebebejunskjd          email    akhilbv1 gmail com              mobileNum    12345678              password    1234567              username    akhil        Override public AllUserDetailsKeyModel deserialize JsonElement json  Type typeOfT        JsonDeserializationContext context  throws JsonParseException        final JsonObject jsonObject   json getAsJsonObject         Gson gson   new Gson         Type AllUserDetailsResponseModel           new TypeToken lt HashMap lt String  AllUserDetailsResponseModel gt  gt      getType         HashMap lt String  AllUserDetailsResponseModel gt  user           gson fromJson jsonObject  AllUserDetailsResponseModel       AllUserDetailsKeyModel result   new AllUserDetailsKeyModel        result setResult user       return result            The code in comments is my object model and u should replaceAllUserDetailsKeyModel with your model class and add this to the rest client like below -  private Converter Factory createGsonConverter         GsonBuilder gsonBuilder   new GsonBuilder        gsonBuilder registerTypeAdapter AllUserDetailsKeyModel class  new UserDetailsDeserializer         Gson gson   gsonBuilder create        return GsonConverterFactory create gson         This the custom Convertor for Retrofit   In your onResponse you just loop with hasmaps and get value by key and my model class looks like below -  public class AllUserDetailsKeyModel      private Map lt String  AllUserDetailsResponseModel gt  result     public Map lt String  AllUserDetailsResponseModel gt  getResult         return result         public void setResult Map lt String  AllUserDetailsResponseModel gt  result        this result   result           probably you need to give a Type T where T is your data Type and my model consists only of a hashmap and getters and setters for that   And finally set Custom Convertor to retrofit like below -  addConverterFactory createGsonConverter     Let me know if you need more clarifications

User · Answer

Use GenericTypeIndicator to get List of Child Node from Firebase ArrayList structured DataBase       Start of Code    Firebase ref   new Firebase FIREBASE URL      ref addValueEventListener new ValueEventListener           Override       public void onDataChange DataSnapshot snapshot            GenericTypeIndicator lt List lt YourClassName gt  gt  t   new GenericTypeIndicator lt List lt YourClassName gt  gt              List lt YourClassName gt  messages   snapshot getValue t            Log d  Get Data Size   messages size                                Override       public void onCancelled FirebaseError firebaseError             Log e  The read failed    firebaseError getMessage

User · Answer

I did something like this     Firebase ref   new Firebase FIREBASE URL   ref addValueEventListener new ValueEventListener       Override public void onDataChange DataSnapshot snapshot        Map lt String  Object gt  objectMap    HashMap lt String  Object gt                    dataSnapshot getValue        List lt Match gt    new ArrayList lt Match gt         for  Object obj   objectMap values              if  obj instanceof Map                Map lt String  Object gt  mapObj    Map lt String  Object gt   obj              Match match   new Match                match setSport  String  mapObj get Constants SPORT                match setPlayingWith  String  mapObj get Constants PLAYER                list add match                          Override   public void onCancelled FirebaseError firebaseError

User · Answer

Saving and Retriving data to - from Firebase   deprecated ver 2 4 2    Firebase fb parent   new Firebase  YOUR-FIREBASE-URL     Firebase fb to read   fb parent child  students names    Firebase fb put child   fb to read push       REMEMBER THIS FOR PUSH METHOD    INSERT DATA TO STUDENT - NAMES  I Use Push Method fb put child setValue  Zacharia      OR fb put child setValue YOUR MODEL   fb put child setValue  Joseph      OR fb put child setValue YOUR MODEL   fb put child setValue  bla blaaa      OR fb put child setValue YOUR MODEL      GET DATA FROM FIREBASE INTO ARRAYLIST fb to read addValuesEventListener          public void onDataChange DataSnapshot result           List lt String gt  lst   new ArrayList lt String gt        Result will be holded Here         for DataSnapshot dsp   result getChildren                 lst add String valueOf dsp getKey        add result into array list                     NOW YOU HAVE ARRAYLIST WHICH HOLD RESULTS     for String data lst             Toast make context data Toast LONG LENGTH  show

User · Answer

If you use Kotlin  the next one is a good solution   myRef addListenerForSingleValueEvent object   ValueEventListener     override fun onDataChange dataSnapshot  DataSnapshot          val list   dataSnapshot children map   it getValue YourClass  class java            Log d  TAG    Value is   list

User · Answer

Use Gson is my favorite solution   mFirebaseRef addValueEventListener new ValueEventListener          Override     public void onDataChange DataSnapshot dataSnapshot            Type StringListType   new TypeToken lt List lt String gt  gt      getType            List lt String gt  td   new Gson   fromJson dataSnapshot getValue    StringListType               if you think the code to get TypeToken is unintuitive  You can write a class to contain all types you need  So next time  you can get those types quickly   class TypeTokens      static public final Type StringListType   new TypeToken lt List lt String gt  gt      getType        static public final Type StringMapType   new TypeToken lt Map lt String  String gt  gt      getType        static public final Type LongMapType   new TypeToken lt Map lt String  Long gt  gt      getType        static public final Type DateMapType   new TypeToken lt Map lt String  Date gt  gt      getType

User · Answer

Firebase stores a sequence of values in this format    -K-Y Rhyxy9kfzIWw7Jq    Value 1   -K-Y RqDV zbNLPJYnOA    Value 2   -K-Y SBoKvx6gAabUPDK    Value 3    If that is how you have them  you are getting the wrong type  The above structure is represented as a Map  not as a List   mFirebaseRef   new Firebase FIREBASE URL    mFirebaseRef addValueEventListener new ValueEventListener          Override     public void onDataChange DataSnapshot dataSnapshot            Map lt String  Object gt  td    HashMap lt String Object gt   dataSnapshot getValue             List lt Object gt  values   td values               notifyDataSetChanged                Override     public void onCancelled FirebaseError firebaseError

User · Answer

as Frank said Firebase stores sequence of values in the format of  key    Value  which is a Map structure  to get List from this sequence you have to    initialize GenericTypeIndicator with HashMap of String and your Object  get value of DataSnapShot as GenericTypeIndicator into Map  initialize ArrayList with HashMap values      GenericTypeIndicator lt HashMap lt String  Object gt  gt  objectsGTypeInd   new GenericTypeIndicator lt HashMap lt String  Object gt  gt        Map lt String  Object gt  objectHashMap   dataSnapShot getValue objectsGTypeInd   ArrayList lt Object gt  objectArrayList   new ArrayList lt Object gt  objectHashMap values         Works fine for me  Hope it helps

User · Answer

I hope below code works  Firebase ref   new Firebase FIREBASE URL      ref addValueEventListener new ValueEventListener            Override       public void onDataChange DataSnapshot snapshot              Log e  Count       snapshot getChildrenCount               for  DataSnapshot postSnapshot  snapshot getChildren                   lt YourClass gt  post   postSnapshot getValue  lt YourClass gt  class               Log e  Get Data   post  lt YourMethod gt                                 Override       public void onCancelled FirebaseError firebaseError              Log e  The read failed     firebaseError getMessage

User · Answer

FirebaseDatabase mFirebaseDatabase   FirebaseDatabase getInstance     DatabaseReference databaseReference      mFirebaseDatabase getReference FIREBASE URL           databaseReference addValueEventListener new ValueEventListener                  Override             public void onDataChange DataSnapshot dataSnapshot                     for  DataSnapshot childDataSnapshot   dataSnapshot getChildren                          Log v TAG     childDataSnapshot getKey       displays the key for the node                     Log v TAG     childDataSnapshot child --ENTER THE KEY NAME eg  firstname or email etc --  getValue         gives the value for given keyname                                          Override         public void onCancelled DatabaseError databaseError                         Hope it helps

User · Answer

Works Like a Charm   final DatabaseReference senderDb   FirebaseDatabase getInstance   getReference Constant NODE MESSAGE  child myId         otherId        senderDb addValueEventListener new ValueEventListener              Override         public void onDataChange DataSnapshot dataSnapshot                Map lt String  Object gt  td    HashMap lt String Object gt   dataSnapshot getValue                 for  DataSnapshot childDataSnapshot   dataSnapshot getChildren                      DatabaseReference objRef   senderDb child  childDataSnapshot getKey                     Map lt String Object gt  taskMap   new HashMap lt String Object gt                     taskMap put  is read    1                    objRef updateChildren taskMap     should I use setValue                       Log v  Testing      childDataSnapshot getKey       displays the key for the node                              notifyDataSetChanged                        Override         public void onCancelled DatabaseError databaseError

User · Answer

In my case only given solution worked fine   Screenshot of Firebase ArrayList structure     How to fetch whole list from Firebase from DataSnapshot   GenericTypeIndicator lt Map lt String  List lt Education gt  gt  gt  genericTypeIndicator   new GenericTypeIndicator lt Map lt String  List lt Education gt  gt  gt        Map lt String  List lt Education gt  gt  hashMap   dataSnapshot getValue genericTypeIndicator    for  Map Entry lt String List lt Education gt  gt  entry   hashMap entrySet            List lt Education gt  educations   entry getValue            for  Education education  educations                Log i TAG  education Degree                  Education java   Model class    public class Education implements Serializable       public String Degree      public String Result      Hope this would works fine

User · Answer

private FirebaseDatabase firebaseDatabase   FirebaseDatabase getInstance        private DatabaseReference databaseReference   firebaseDatabase getReference        private DatabaseReference mChildReference  databaseReference child  data       mChildReference addValueEventListener new ValueEventListener                  Override             public void onDataChange  NonNull DataSnapshot dataSnapshot                    for DataSnapshot ds   dataSnapshot getChildren                          User commandObject   ds getValue User class                       Log d  TAG   commandObject getMsg                                       Toast makeText MainActivity this dataSnapshot toString   Toast LENGTH SHORT  show                                Override             public void onCancelled  NonNull DatabaseError databaseError                                 This will help you  you just have to create a model class containing String msg

User · Answer

DatabaseReference mRootRef   FirebaseDatabase getInstance   getReference            DatabaseReference mMainMenuRef   mRootRef child  tut master     main         DatabaseReference mSubMenuRef   mMainMenuRef child  english     sub         List lt Tutorial gt    tutorialNames new ArrayList lt  gt             mSubMenuRef addValueEventListener new ValueEventListener                  Override             public void onDataChange DataSnapshot dataSnapshot                     for DataSnapshot ds   dataSnapshot getChildren                          long id   ds child  id   getValue Long class                       String name   ds child  name   getValue String class                        Tutorial tut   new Tutorial                        tut setTutId id                          tut setTutName name                       tutList add tut                                                   Override             public void onCancelled  NonNull DatabaseError databaseError

User · Answer

mDatabase child  token   addListenerForSingleValueEvent new ValueEventListener                  Override             public void onDataChange DataSnapshot dataSnapshot                  for  DataSnapshot snapshot dataSnapshot getChildren                                     String key  snapshot getKey                     String value snapshot getValue   toString                                                Override             public void onCancelled DatabaseError databaseError                    Toast makeText ListUser this databaseError toString   Toast LENGTH SHORT  show                                Only work If child have no SubChild

[android] how to get all child list from Firebase android

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