Kotlin firebase'den veri getirme ufak bir yardım lazım

class User {    var user_id:String?=null    var username:String?=null    var image:Int?=null    var score:String?=null    constructor(user_id: String, username: String, image: Int, score: String) {        this.user_id = user_id        this.username = username        this.image = image        this.score = score    }    constructor() {}}

class Adapter(    val leaders: MutableList<User>,    val context: Context) : RecyclerView.Adapter<Adapter.LeadersViewHolder>() {    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): LeadersViewHolder {        return LeadersViewHolder(LayoutInflater.from(context).inflate(R.layout.leader_row_layout, parent, false))    }    override fun getItemCount() = leaders.size    override fun onBindViewHolder(holder: LeadersViewHolder, position: Int) {        with(leaders[position]) {            holder.nickname.text = username            holder.point.text = score            holder.image.setImageResource(image!!)        }    }    class LeadersViewHolder(view: View) : RecyclerView.ViewHolder(view) {        val image= view.leadersRowIV        val nickname= view.leadersRowNickNameTV        val point= view.leadersRowPointTV    }}

class Activity : AppCompatActivity() {    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.leaders_activity)        val mLayoutManager = LinearLayoutManager(this)        with(leadersRV) {            layoutManager = mLayoutManager            adapter = Adapter(generateLeadersData(), this@Activity)        }    }    private fun generateLeadersData(): MutableList<User> {        var referans = FirebaseDatabase.getInstance()    }  }

var referans = FirebaseDatabase.getInstance()
val userList : MutableList<User> = arrayListOf()

referans.child("User").orderByChild("score").addListenerForSingleValueEvent(object : ValueEventListener {
override fun onDataChange(userSnapshots : DataSnapshot) {

for(userSnapshot in userSnapshots.children ){
val mUser = userSnapshot.getValue(User::class.java)
tempList.add(mUser!!)

}

}

override fun onCancelled(userSnapshots DatabaseError) {
}
}

data class User(val user_id:String = "",
val username:String = "",
val image:Int = 0,
var score:String = "")

val ref = FirebaseDatabase.getInstance().reference
ref.child("User").orderByChild("score").addListenerForSingleValueEvent(object : ValueEventListener {    
override fun onDataChange(userSnapshots : DataSnapshot) {        
    userSnapshots.children.forEach { snap ->          
    val mUser = snap.getValue(User::class.java) ?: return@forEach          
    tempList.add(mUser)      
 }
    }    
override fun onCancelled(e: DatabaseError) {    }
}

data class User(val user_id:String = "",
val username:String = "",
val image:Int = 0,
var score:String = "")

val ref = FirebaseDatabase.getInstance().reference
ref.child("User").orderByChild("score").addListenerForSingleValueEvent(object : ValueEventListener {    
override fun onDataChange(userSnapshots : DataSnapshot) {        
    userSnapshots.children.forEach { snap ->          
    val mUser = snap.getValue(User::class.java) ?: return@forEach          
    tempList.add(mUser)      
 }
    }    
override fun onCancelled(e: DatabaseError) {    }
}

var referans = FirebaseDatabase.getInstance()
val userList : MutableList<User> = arrayListOf()

referans.child("User").orderByChild("score").addListenerForSingleValueEvent(object : ValueEventListener {
override fun onDataChange(userSnapshots : DataSnapshot) {

for(userSnapshot in userSnapshots.children ){
val mUser = userSnapshot.getValue(User::class.java)
tempList.add(mUser!!)

}

}

override fun onCancelled(userSnapshots DatabaseError) {
}
}

    
private fun generateLeadersData(): MutableList<User> {
     val leaders = mutableListOf(User(...),User(...))

     val filteredLeaders = leaders
          .filter { it.point > 0 }
          .sortedByDescending { it.point }

     return filteredLeaders.toMutableList()
    }