Android中`PreferenceScreen`缺少Header/title

   <PreferenceCategory android:title="General Settings">

       <CheckBoxPreference

           android:key="pref_key_enable_notifications"

           android:title="Enable Notifications" />

       <ListPreference

           android:key="pref_key_theme"

           android:title="Theme"

           android:entries="@array/theme_entries"

           android:entryValues="@array/theme_values" />

   </PreferenceCategory>

   <PreferenceCategory android:title="Account Settings">

       <EditTextPreference

           android:key="pref_key_username"

           android:title="Username" />

       <EditTextPreference

           android:key="pref_key_password"

           android:title="Password"

           android:inputType="textPassword" />

   </PreferenceCategory>

   android:layout_width="match_parent"

   android:layout_height="wrap_content"

   android:orientation="vertical">

   <TextView

       android:id="@+id/header_title"

       android:layout_width="match_parent"

       android:layout_height="wrap_content"

       android:text="Settings"

       android:textSize="20sp"

       android:textStyle="bold"

       android:padding="16dp" />

   <ListView

       android:id="@android:id/list"

       android:layout_width="match_parent"

       android:layout_height="wrap_content" />

   android:layout="@layout/custom_preference_layout">

   <!-- 设置项 -->