I have a OnPreferenceClickListener which should remove a specific Preference (with key preference_to_remove) from a PreferenceScreen.
The problem is that my solution works when preference_to_remove is not located inside a nested PreferenceScreen but does not work, when it is inside a nested screen AND the screen orientation changes. Before screen orientation changes, nested screens are working as expected, too.
The following code contains two version, one with a flat non-nested PreferenceScreen and the broken nested PreferenceScreen.
What is the reason that the nested version is not able to remove the Preference with key preference_to_remove after screen orientation changes? What would be a solution besides using only flat PreferenceScreens and Intents to start new PreferenceScreens as pseudo children?
PS: I am using PreferenceActivity for FroYo compatibility.
How to reproduce with Test-App
Open App → Click Flat-Button → Click preference_to_click which should remove preference_to_remove. → Orientation change → Click preference_to_click to remove preference_to_remove again. Preference removed? Success!
Open App → Click Subscreen-Button → Click Test → Now repeat the steps from the first test, but this time preference_to_remove will be not not removable after orientation changing.
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 (Nested PreferenceScreen)
<?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>
Diff of PrefFlatActivity.java and PrefSubscreenActivity.java
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 (Working)
/**
* 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 (Nested, broken after orientation change)
/**
* 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;
}
}
}
