我有一个OnPreferenceClickListener，应该从Preference删除特定的preference_to_remove（包含密钥PreferenceScreen）。
问题是我的解决方案在preference_to_remove不在嵌套PreferenceScreen内但在包含在嵌套屏幕内并且屏幕方向发生变化时不起作用时有效。在屏幕方向更改之前，嵌套屏幕也按预期工作。
以下代码包含两个版本，一个版本为平面非嵌套PreferenceScreen，另一个版本为嵌套PreferenceScreen。
在屏幕方向更改后，嵌套版本无法使用键Preference删除preference_to_remove的原因是什么？除了仅使用平展PreferenceScreens和Intents启动新的PreferenceScreens作为伪孩子之外，还有什么解决方案？
PS：我使用PreferenceActivity来兼容FroYo。
如何使用Test-App重现
打开应用程序→单击平面按钮→单击preference_to_click，这将删除preference_to_remove。 →方向更改→单击preference_to_click再次删除preference_to_remove。偏好被删除了吗？成功了！
打开应用程序→单击子屏幕 - 按钮→单击测试→现在重复第一次测试中的步骤，但这次更改方向后preference_to_remove不会被删除。
pref_flat.xml
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
<Preference
android:key="preference_to_click"
android:persistent="false"
android:title="preference_to_click" />
<Preference
android:key="preference_to_remove"
android:title="preference_to_remove" />
</PreferenceScreen>
pref_subscreen.xml（嵌套的首选项屏幕）
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
<PreferenceScreen
android:key="subscreen"
android:persistent="false"
android:title="Test" >
<Preference
android:key="preference_to_click"
android:persistent="false"
android:title="preference_to_click" />
<Preference
android:key="preference_to_remove"
android:title="preference_to_remove" />
</PreferenceScreen>
</PreferenceScreen>
PrefFlatActivity.java和PrefSubscreenActivity.java的差异
1c1
< public class PrefFlatActivity extends PreferenceActivity {
---
> public class PrefSubscreenActivity extends PreferenceActivity {
5,6c5,7
< public static final String PREFERENCE_TO_CLICK = "preference_to_click";
< public static final String PREFERENCE_TO_REMOVE = "preference_to_remove";
---
> private static final String PREFERENCE_TO_CLICK = PrefFlatActivity.PREFERENCE_TO_CLICK;
> private static final String PREFERENCE_TO_REMOVE = PrefFlatActivity.PREFERENCE_TO_REMOVE;
> private static final String PREFERENCE_SUBSCREEN = "subscreen";
15c16
< addPreferencesFromResource(R.xml.pref_flat);
---
> addPreferencesFromResource(R.xml.pref_subscreen);
28c29
< PreferenceScreen screen = getPreferenceScreen();
---
> PreferenceScreen screen = (PreferenceScreen) findPreference(PREFERENCE_SUBSCREEN);
PrefFlatActivity.java（工作）
/**
* Works as expected. Clicking toggles the "visibility" of the PREFERENCE_TO_REMOVE Preference.
*/
public class PrefFlatActivity extends PreferenceActivity {
/**
* Preference keys.
*/
public static final String PREFERENCE_TO_CLICK = "preference_to_click";
public static final String PREFERENCE_TO_REMOVE = "preference_to_remove";
private final String PREF_NAME = getClass().getName() + ".pref";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getPreferenceManager().setSharedPreferencesName(PREF_NAME);
addPreferencesFromResource(R.xml.pref_flat);
findPreference(PREFERENCE_TO_CLICK)
.setOnPreferenceClickListener(new OnFlatClickListener());
}
/**
* Removes or adds Preference with key PREFERENCE_TO_REMOVE when clicked.
*/
private class OnFlatClickListener implements OnPreferenceClickListener {
private Preference mRescuedPreference;
public boolean onPreferenceClick(Preference preference) {
PreferenceScreen screen = getPreferenceScreen();
Preference prefToRemove = screen.findPreference(PREFERENCE_TO_REMOVE);
Log.d("test", "Found PREFERENCE_TO_REMOVE: " + (prefToRemove != null));
if (prefToRemove != null) {
screen.removePreference(prefToRemove);
mRescuedPreference = prefToRemove; // Rescue reference to re-add it later.
}
else {
screen.addPreference(mRescuedPreference);
}
return true;
}
}
}
PrefSubscreenActivity.java（嵌套，在方向更改后损坏）
/**
* Broken after orientation change. Clicking does not remove/add PREFERENCE_TO_REMOVE.
*/
public class PrefSubscreenActivity extends PreferenceActivity {
/**
* Preference keys.
*/
private static final String PREFERENCE_TO_CLICK = PrefFlatActivity.PREFERENCE_TO_CLICK;
private static final String PREFERENCE_TO_REMOVE = PrefFlatActivity.PREFERENCE_TO_REMOVE;
private static final String PREFERENCE_SUBSCREEN = "subscreen";
private final String PREF_NAME = getClass().getName() + ".pref";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getPreferenceManager().setSharedPreferencesName(PREF_NAME);
addPreferencesFromResource(R.xml.pref_subscreen);
findPreference(PREFERENCE_TO_CLICK)
.setOnPreferenceClickListener(new OnFlatClickListener());
}
/**
* Removes or adds Preference with key PREFERENCE_TO_REMOVE when clicked.
*/
private class OnFlatClickListener implements OnPreferenceClickListener {
private Preference mRescuedPreference;
public boolean onPreferenceClick(Preference preference) {
PreferenceScreen screen = (PreferenceScreen) findPreference(PREFERENCE_SUBSCREEN);
Preference prefToRemove = screen.findPreference(PREFERENCE_TO_REMOVE);
Log.d("test", "Found PREFERENCE_TO_REMOVE: " + (prefToRemove != null));
if (prefToRemove != null) {
screen.removePreference(prefToRemove);
mRescuedPreference = prefToRemove; // Rescue reference to re-add it later.
}
else {
screen.addPreference(mRescuedPreference);
}
return true;
}
}
}
答案 0 :(得分：1)
编辑：我一直无法按照您的要求开始工作。我仔细阅读了Preference s的来源以及它们如何处理状态而没有任何运气，所以我可能遗漏了一些明显的东西（不是经常发生的事情吗？）
我做了一些测试，我相信它用来显示嵌套PreferenceScreen的{{1}}和/或Dialog的状态表现得与我们两个都没有预计。例如，使用PreferenceScreen而不是PreferenceCategory时，未遵循此行为。
PreferenceScreen这种方式，您可以随时尝试使用片段：http://developer.android.com/reference/android/preference/PreferenceActivity.html
但是，我怀疑你是出于遗留原因而避免这种情况。
Preference：Building Preference screen in code depending on another setting
Preference希望你很快得到这个想法。我确信解决方案最终会在我们身上出现;它不会那么难！ 这里希望;）
原始来源（主要）保留在下方：
http://developer.android.com/reference/android/app/Activity.html#ConfigurationChanges
https://stackoverflow.com/questions/3542333/how-to-prevent-custom-views-from-losing-state-across-screen-orientation-changes/8127813#8127813
<activity ..
android:configChanges="orientation|keyboardHidden" .. >
推荐阅读：http://developer.android.com/guide/topics/resources/runtime-changes.html