从firebase正常接收数据，但没有得到选择

Question

我正在从Firebase接收数据，并且Spinner中的数据加载正常，但是当我选择任何项目时onItemSelectListener不起作用，或者我们可以说项目没有从Spinner中获得选择

public class Center_changes extends AppCompatActivity {

    ArrayList<String> array_list=new ArrayList<>();
    EditText center_name,center_url;
    Button save_btn,delete_btn;
    Spinner centers_spn;
    ArrayList<String> arrayList2=new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_center_changes);
        center_name=(EditText)findViewById(R.id.center_name);
        center_url=(EditText)findViewById(R.id.center_url);
        save_btn=(Button)findViewById(R.id.save_btn);
        delete_btn=(Button)findViewById(R.id.delete_btn);
        centers_spn=(Spinner)findViewById(R.id.center_spinner_1);
        centers_spn.setSelected(true);
        FirebaseDatabase database=FirebaseDatabase.getInstance();
       DatabaseReference data_ref=FirebaseDatabase.getInstance().getReference();
       Query arry_q=data_ref.child("centers").orderByChild("center_name");
        arry_q.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                if (dataSnapshot.hasChildren())
                {
                    array_list.clear();
                    for (DataSnapshot dataSnapshot1:dataSnapshot.getChildren())
                    {
                        data dat=dataSnapshot1.getValue(data.class);
                        array_list.add(dat.getCenter_name());

                    }
                }

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
        ArrayAdapter<String> adapter=new ArrayAdapter<>(this,R.layout.support_simple_spinner_dropdown_item,array_list);
        //adapter.setDropDownViewResource(R.layout.support_simple_spinner_dropdown_item);
        centers_spn.setAdapter(adapter);
        centers_spn.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                // ((TextView)parent.getChildAt(position)).setTextSize(25);
                // ((TextView)parent.getChildAt(position)).setTextColor(Color.RED);
                Toast.makeText(Center_changes.this,"Item="+parent.getSelectedItem().toString()+" and id="+parent.getSelectedItemId(), Toast.LENGTH_SHORT).show();
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

    }