private fun writeDataOnFirestore(){
        mFirestore.collection("student_info").document("student_list")
                .set(studentInfo)
                .addOnSuccessListener {
                    Toast.makeText(mContext, "DocumentSnapshot successfully written!", Toast.LENGTH_LONG).show()
                    Log.d(TAG, "DocumentSnapshot successfully written!")

                    initListView()
                }.addOnFailureListener {
                    e -> Log.e(TAG, "Error writing document", e)
                }
    }