forced to close on screen orientation changes
<p>My app is forced to close after I press "Ctrl-F11" to rotate screen. Here's the error log:   </p>

<pre><code> 01-02 13:47:30.663: E/AndroidRuntime(498): FATAL EXCEPTION: main
 01-02 13:47:30.663: E/AndroidRuntime(498): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ecnu.sei.manuzhang.study/com.ecnu.sei.manuzhang.study.Main}: java.lang.ClassCastException: android.widget.ExpandableListView$SavedState
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:2832)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.ActivityThread.access$1600(ActivityThread.java:117)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.os.Handler.dispatchMessage(Handler.java:99)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.os.Looper.loop(Looper.java:130)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.ActivityThread.main(ActivityThread.java:3683)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at java.lang.reflect.Method.invokeNative(Native Method)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at java.lang.reflect.Method.invoke(Method.java:507)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at dalvik.system.NativeStart.main(Native Method)
 01-02 13:47:30.663: E/AndroidRuntime(498): Caused by: java.lang.ClassCastException: android.widget.ExpandableListView$SavedState
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.widget.ListView.onRestoreInstanceState(ListView.java:3763)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.View.dispatchRestoreInstanceState(View.java:6278)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchThawSelfOnly(ViewGroup.java:1228)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.widget.AdapterView.dispatchRestoreInstanceState(AdapterView.java:767)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:1215)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:1215)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:1215)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:1215)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:1215) 
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:1215)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:1215)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:1215)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.view.View.restoreHierarchyState(View.java:6257)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at com.android.internal.policy.impl.PhoneWindow.restoreHierarchyState(PhoneWindow.java:1486)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.Activity.onRestoreInstanceState(Activity.java:844)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.TabActivity.onRestoreInstanceState(TabActivity.java:58)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.Activity.performRestoreInstanceState(Activity.java:816)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.Instrumentation.callActivityOnRestoreInstanceState(Instrumentation.java:1096)
 01-02 13:47:30.663: E/AndroidRuntime(498):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1625)
 01-02 13:47:30.663: E/AndroidRuntime(498):     ... 12 more 
</code></pre>

<p>As it shows, it has something to do with an ExpandableListView. Thus, I attach the suspected activity and its layout here:    </p>

<pre><code>public class StudyHalls extends ExpanableListActivity {
@Override 
public void onCreate(Bundle savedInstanceState) {
    Log.d(TAG, "on create");
    super.onCreate(savedInstanceState);
    setContentView(R.layout.halls);
            ...
    }
    ...
 }
</code></pre>

<p>halls.xml</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
 &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" &gt;

&lt;ExpandableListView
    android:id="@id/android:list"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
/&gt;

&lt;/LinearLayout&gt;
</code></pre>
