如何在方向更改时保留选定微调器/下拉项的状态？

Question

我在我的代码中使用微调器下拉菜单，其中我有 4 到 5 个动态填充的值，假设我将“苹果”设置为默认值，然后从下拉列表中选择“橙子”并将屏幕旋转为横向纵向，它会与与之关联的视图一起返回默认的“苹果”。如何保存状态，以便当我选择“橙色”并旋转到横向时，它会填充选定的值/保持在相同的选定状态和保持视图完整/填充在与所选值相对应的纵向模式中选择的视图。这是我使用的适配器代码：

public class MarketsSpinnerAdapter extends CustomRowAdapter<AdapterRow> {


    private List<AdapterRow> mRenderList;

    public MarketsSpinnerAdapter(final Context context, final List<AdapterRow> renderList) {
        super(context);


        mRenderList = new ArrayList<AdapterRow>();
        mRenderList.addAll(renderList);
    }

    @Override
    protected void setEntries(final List<AdapterRow> renderList) {
        mRenderList = renderList;
    }

    @Override
    protected List<AdapterRow> getEntries() {
        return mRenderList;
    }

    @Override
    public View getDropDownView(final int position, final View convertView, final ViewGroup parent) {
        return getEntries().get(position).getDropDownView(mContext, convertView);
    }

}

各自片段中的对应用法：

 private void populateCategoryRows(final Cursor cursor) {
            mCategories.clear();
            mAllCategories.clear();
            cursor.moveToPosition(-1);
            Map<String, String> categoryParentNames = new HashMap<String, String>();

            int selectedPosition = 0;
            String previousHeader = "";
            String previousAllHeader = "";

            while (cursor.moveToNext()) {
                final int categoryLevel = cursor.getInt(cursor.getColumnIndex(MarketsCategory.Columns.LEVEL));
                final String categoryName = cursor.getString(cursor.getColumnIndex(MarketsCategory.Columns.NAME));
                final String categoryDisplayName = cursor.getString(cursor.getColumnIndex(MarketsCategory.Columns.DISPLAY_NAME));

                if (categoryLevel == 1) {
                    categoryParentNames.put(categoryName, categoryDisplayName);
                }
            }

            cursor.moveToPosition(-1);
            while (cursor.moveToNext()) {
                final int categoryLevel = cursor.getInt(cursor.getColumnIndex(MarketsCategory.Columns.LEVEL));
                final boolean categoryIsDefault = cursor.getInt(cursor.getColumnIndex(MarketsCategory.Columns.IS_DEFAULT)) == 1;
                final boolean categoryIsSelected = cursor.getInt(cursor.getColumnIndex(MarketsCategory.Columns.IS_SELECTED)) == 1;
                final String categoryParent = cursor.getString(cursor.getColumnIndex(MarketsCategory.Columns.PARENT));
                final String categoryName = cursor.getString(cursor.getColumnIndex(MarketsCategory.Columns.NAME));
                final String categoryDisplayName = cursor.getString(cursor.getColumnIndex(MarketsCategory.Columns.DISPLAY_NAME));


                if (categoryLevel == 2 ) {
                    String categoryParentDisplayName = categoryParentNames.get(categoryParent);
                        if (!categoryParent.equals(previousHeader)) {
                            if (categoryIsSelected) {

                                mCategories.add(new CategoryHeader(categoryParentDisplayName));
                                previousHeader = categoryParent;
                            }
                        }

                        if (!categoryParent.equals(previousAllHeader)) {
                            mAllCategories.add(new CategoryHeader(categoryParentDisplayName));
                            previousAllHeader = categoryParent;
                        }

                        if (categoryIsSelected) {
                            mCategories.add(new SpinnerMarketCategoryRow(categoryName, categoryDisplayName, categoryParent));
                        }
                        mAllCategories.add(new MarketsCategoryCheckableRow(categoryName, categoryDisplayName, categoryIsSelected, categoryIsDefault));

                        if(categoryIsDefault){
                            selectedPosition = mCategories.size()-1;
                        }
                }
            }

            mSpinnerAdapter = new MarketsSpinnerAdapter(Application.getAppContext(), mCategories);
            headerView.setSpinnerAdapter(mSpinnerAdapter);
            headerView.setSpinnerSelectedItemPosition(selectedPosition);
        }
        if (selectedItem instanceof SpinnerMarketCategoryRow) {
            selectedCategory = (SpinnerMarketCategoryRow) mSpinnerAdapter.getItem(position);
        } else {
            if (mSpinnerAdapter.getCount() - 1 >= position + 1) {
                selectedCategory = (SpinnerMarketCategoryRow) mSpinnerAdapter.getItem(position + 1);
            } else {
                selectedCategory = (SpinnerMarketCategoryRow) mSpinnerAdapter.getItem(position - 1);
            }
        }

        final MarketsFragment parentFragment = (MarketsFragment) getParentFragment();
        parentFragment.onCategorySelected(selectedCategory.getCategoryName(), selectedCategory.getCategoryParentName());
    }
@Override
    public void showResults(final Uri uri) {
        LayoutUtils.showResults(getView(), headerView.getSpinnerId());
        headerView.setVisibility(View.VISIBLE);
    }

    @Override
    public void showNoResults(final Uri uri) {
        final MarketsFragment parentFragment = (MarketsFragment) getParentFragment();
        parentFragment.hideSpinner();
        //LayoutUtils.showNoResult(getView(), headerView.getSpinnerId());
    }

    @Override
    public void onDismiss(DialogInterface dialog) {
        headerView.setSelected(false);
    }
    @Override
    public void onNothingSelected(IcsAdapterView<?> parent) {
    }

有什么想法吗？

谢谢！

Answer 1

你可以这样做......

@Override
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putInt("yourSpinner", yourSpinner.getSelectedItemPosition());
    // do this for each or your Spinner
    // You might consider using Bundle.putStringArray() instead
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // initialize all your visual fields        
    if (savedInstanceState != null) {
        yourSpinner.setSelection(savedInstanceState.getInt("yourSpinner", 0));
        // do this for each of your text views
    }
}

希望对你有帮助

Answer 2

如果设备的配置（由Resources.Configuration 类定义）发生更改，则显示用户界面的任何内容都需要更新以匹配该配置，因此您的Activity 除非您另有指定，否则配置更改（例如屏幕方向、语言、输入设备等的变化）将导致您当前的活动被破坏，通过 onPause()、onStop() 和 onDestroy() 的正常 Activity lifecycle process 视情况而定。

如果活动在前台或对用户可见，则在该实例中调用 onDestroy() 后，将创建活动的新实例，无论 savedInstanceState 之前的实例是从 onSaveInstanceState(Bundle) 生成的。

这样做是因为任何应用程序资源（包括布局文件）都可以根据任何配置值进行更改。在某些特殊情况下（就像您的一样，如果我做对了，如果您在当前 UI 上只有微调器/下拉菜单并且您不需要经历完整的 Activity 生命周期），您可能希望绕过基于一个重新启动您的 Activity或更多类型的配置更改。这是通过其清单中的 android:configChanges 属性完成的，并且/或者您也可以使用 onSaveInstanceState(Bundle)，它是活动被销毁并从开始重新创建时的调用者。

你有两种方法可以解决这个问题_

1_

• 1. 在您的 Activity 标签的 Manifest 文件中添加 android:configChanges="orientation"。

 <?xml version="1.0" encoding="utf-8"?>
 <manifest ...
 >
 <application ...
   >      
    <activity
        android:name="SpinnerActivity"
        android:configChanges="orientation" >
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
 </application>

 </manifest>

• 2、OverrideonConfigurationChanged，当你的Activity运行时设备配置发生变化时系统会调用它。

 @Override
 public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    int orientation = newConfig.orientation;

    switch (orientation) {
    case Configuration.ORIENTATION_LANDSCAPE:
        // do what you want when user is in LANDSCAPE
        break;

    case Configuration.ORIENTATION_PORTRAIT:
        // do what you want when user is in PORTRAIT
        break;
    }

}

2_

使用 put 方法将值存储在 onSaveInstanceState() 中：

protected void onSaveInstanceState(Bundle savedInstanceState) {
    super.onSaveInstanceState(savedInstanceState);
    //Put your spinner values to restore later...
    savedInstanceState.putLong("yourSpinnerValKey", yourSpinner.getSelectedItemPosition());
}

并恢复 onCreate() 中的值：

public void onCreate(Bundle savedInstanceState) {
    if (savedInstanceState!= null) {
     //get your values to restore...
        value = savedInstanceState.getLong("param");
    }
}

这肯定会解决您的问题，并且在屏幕方向更改时不会刷新您的微调器。我希望这对你和所有人都有帮助！ :)