Get data from firebase realtime database in android

Question

I am trying to get data from firebase realtime database in android. I have created a json data file and imported the json file in firebase database. The data file looks like this :

{
    "data": [
        {
        "name" : "one",
        "age" : "ten"
        },{
        "name" : "two",
        "age" : "twenty"
        }
    ]
}

I have created a POJO class. Now how can I get all the json objects from the array? I've searched for a while but can't understand what will be the reference & child here.

Answer 1

I would recommend changing your Firebase structure as following:

• replace [] with {} as Firebase recommends using this practice
• add a specific unique id for every user(or item) you have in data node.

Take this example:

As you can see in the picture every user has a specific id. Firebase provides for every user an unique id which you can get with String userId= user.getUid();.

You can create unique ids aswell and get them using String key = Database.child("users").push().getKey(); (not advised to be used for user ids)

If you wish to read the data you structured I recommend reading this.

Also read this.

Answer 2

When you said val fireDataBaseRef FirebaseDatabase.getInstance().reference.child("data") you are holding a reference of your root tree. with this reference you can fireDataBaseRef.addChildEventListener(childEventListener)

where

val childEventListener: ChildEventListener = object : ChildEventListener {

        override fun onCancelled(snapshot: DatabaseError?) {}

        override fun onChildMoved(snapshot: DataSnapshot?, p1: String?) {}

        override fun onChildChanged(snapshot: DataSnapshot?, p1: String?) {

        }

        override fun onChildAdded(snapshot: DataSnapshot?, p1: String?) {
            // childs added
        }

        override fun onChildRemoved(snapshot: DataSnapshot?) {

        }
    }

just put some logs in the overrided functions and you will see the action