java - 屏幕旋转后恢复 fragment 中微调器的位置

Question

正如我在标题中所写的那样，我想在屏幕旋转后恢复微调器中的选定位置。尝试通过在 bundle 中保存位置来实现此目的，并在旋转后从 savedInstanceState 获取位置

onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { }

或者

onViewCreated(View view, Bundle savedInstanceState)

或者

onActivityCreated(Bundle savedInstanceState) 

但没有人工作:-/

添加RecipeFragment

public class AddRecipeFragment extends Fragment implements ObservableScrollViewCallbacks {


    private static final String SELECTED_CATEGORY = "SELECTED_CATEGORY";
    private Spinner categoriesSpinner;


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_add_recipe, container, false);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        categoriesSpinner = (Spinner) view.findViewById(R.id.categories_spinner);
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getActivity(), R.array.categories, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        categoriesSpinner.setAdapter(adapter);

        if (savedInstanceState != null) {
            categoriesSpinner.setSelection(savedInstanceState.getInt(SELECTED_CATEGORY, 0), true);
        }
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(SELECTED_CATEGORY, categoriesSpinner.getSelectedItemPosition());
    }
}

我还尝试了 setSelection(position, false) 和 false。

Answer 1

如果这一切都失败了，为什么不使用静态变量呢？!

private static int selectedPosition = 0;

当选择微调项目时

categoriesSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {
    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        selectedPosition = position;
    }

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

以及内部onViewCreated()方法

categoriesSpinner.setSelection(selectedPosition);