自定义对话框中的微调器不会填充

Question

所以我有一个自定义对话框布局，其中有一个微调器。我试图填充它，但似乎仍然是空的。请帮忙！

活动

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.activity_upcoming);

    itemList = (ListView) findViewById(R.id.listView1);

    departmentDialogView = (View)getLayoutInflater().inflate(R.layout.custom_filter_department_dialog, null);


    Spinner spinDepartment = (Spinner) departmentDialogView.findViewById(R.id.spinner_department);

    db = new DatabaseHelper(getApplicationContext());

    allItems = db.getAllItems();
    allProducts = db.getAllProducts();
    departments = this.getDepartments();




    //Set department spinner

    String[] itemsDepartment = departments.toArray(new String[departments.size()]);

    ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,itemsDepartment);

    spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinDepartment.setAdapter(spinnerArrayAdapter);

自定义对话框布局XML

<Spinner
android:id="@+id/spinner_department"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true" />

</RelativeLayout>