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PORemoving children of (sub-) PreferenceScreen not possible after orientation change
 

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  1. PORemoving children of (sub-) PreferenceScreen not possible after orientation change
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    <p>I have a <code>OnPreferenceClickListener</code> which should remove a specific <code>Preference</code> (with key <code>preference_to_remove</code>) from a <code>PreferenceScreen</code>.</p> <p>The problem is that my solution works when <code>preference_to_remove</code> is not located inside a nested <code>PreferenceScreen</code> 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.</p> <p>The following code contains two version, one with a flat non-nested <code>PreferenceScreen</code> and the broken nested <code>PreferenceScreen</code>.</p> <p>What is the reason that the nested version is not able to remove the <code>Preference</code> with key <code>preference_to_remove</code> after screen orientation changes? What would be a solution besides using only flat <code>PreferenceScreens</code> and <code>Intents</code> to start new <code>PreferenceScreens</code> as pseudo children?</p> <p>PS: I am using <code>PreferenceActivity</code> for FroYo compatibility.</p> <p><strong>How to reproduce with Test-App</strong></p> <p>Open App → Click Flat-Button → Click <code>preference_to_click</code> which should remove <code>preference_to_remove</code>. → Orientation change → Click <code>preference_to_click</code> to remove <code>preference_to_remove</code> again. Preference removed? Success!</p> <p>Open App → Click Subscreen-Button → Click Test → Now repeat the steps from the first test, but this time <code>preference_to_remove</code> will be not not removable after orientation changing.</p> <p><a href="http://www.sendspace.com/file/0f69ma" rel="nofollow">Download App (Source)</a></p> <p><strong>pref_flat.xml</strong></p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" &gt; &lt;Preference android:key="preference_to_click" android:persistent="false" android:title="preference_to_click" /&gt; &lt;Preference android:key="preference_to_remove" android:title="preference_to_remove" /&gt; &lt;/PreferenceScreen&gt; </code></pre> <p><strong>pref_subscreen.xml (Nested PreferenceScreen)</strong></p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" &gt; &lt;PreferenceScreen android:key="subscreen" android:persistent="false" android:title="Test" &gt; &lt;Preference android:key="preference_to_click" android:persistent="false" android:title="preference_to_click" /&gt; &lt;Preference android:key="preference_to_remove" android:title="preference_to_remove" /&gt; &lt;/PreferenceScreen&gt; &lt;/PreferenceScreen&gt; </code></pre> <p><strong>Diff of PrefFlatActivity.java and PrefSubscreenActivity.java</strong></p> <pre><code>1c1 &lt; public class PrefFlatActivity extends PreferenceActivity { --- &gt; public class PrefSubscreenActivity extends PreferenceActivity { 5,6c5,7 &lt; public static final String PREFERENCE_TO_CLICK = "preference_to_click"; &lt; public static final String PREFERENCE_TO_REMOVE = "preference_to_remove"; --- &gt; private static final String PREFERENCE_TO_CLICK = PrefFlatActivity.PREFERENCE_TO_CLICK; &gt; private static final String PREFERENCE_TO_REMOVE = PrefFlatActivity.PREFERENCE_TO_REMOVE; &gt; private static final String PREFERENCE_SUBSCREEN = "subscreen"; 15c16 &lt; addPreferencesFromResource(R.xml.pref_flat); --- &gt; addPreferencesFromResource(R.xml.pref_subscreen); 28c29 &lt; PreferenceScreen screen = getPreferenceScreen(); --- &gt; PreferenceScreen screen = (PreferenceScreen) findPreference(PREFERENCE_SUBSCREEN); </code></pre> <p><strong>PrefFlatActivity.java (Working)</strong></p> <pre><code>/** * 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; } } } </code></pre> <p><strong>PrefSubscreenActivity.java (Nested, broken after orientation change)</strong></p> <pre><code>/** * 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; } } } </code></pre>
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