如何返回p0数据库快照[重复]

Question

我怎样才能在有趣的getItemCount() 中返回p0 ？ 我是 kotlin 的新手，我想这就是我不知道的原因

override fun getItemCount(): Int {


        val ref = FirebaseDatabase.getInstance().getReference("proizvodi/Kalendari")
        ref.addListenerForSingleValueEvent(object : ValueEventListener{
            override fun onCancelled(p0: DatabaseError) {
                TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
            }

            override fun onDataChange(p0: DataSnapshot) {

                Log.d("p0",p0.childrenCount.toString())


            }

        })
        return p0 //i want count to return here
    }

Answer 1

试试这个方法

override fun getItemCount(): Int {
        var count = 0 // init count variable 

        val ref = FirebaseDatabase.getInstance().getReference("proizvodi/Kalendari")
        ref.addListenerForSingleValueEvent(object : ValueEventListener{
            override fun onCancelled(p0: DatabaseError) {

            }
            override fun onDataChange(p0: DataSnapshot) {
                Log.d("p0",p0.childrenCount.toString())
                count = p0.childrenCount
            }

        })
        return count  //return count 
    }