topics/ui/settings.jd

page.title=
page.tags= Activity

@jd:body


<div id="qv-wrapper">
<div id="qv">

<h2></h2>
<ol>
  <li><a href="#Overview"></a>
    <ol>
      <li><a href="#SettingTypes"></a></li>
    </ol>
  </li>
  <li><a href="#DefiningPrefs"> XML </a>
    <ol>
      <li><a href="#Groups"></a></li>
      <li><a href="#Intents"> Intent </a></li>
    </ol>
  </li>
  <li><a href="#Activity"> Activity</a></li>
  <li><a href="#Fragment"></a></li>
  <li><a href="#Defaults"></a></li>
  <li><a href="#PreferenceHeaders"></a>
    <ol>
      <li><a href="#CreateHeaders"></a></li>
      <li><a href="#DisplayHeaders"></a></li>
      <li><a href="#BackCompatHeaders"></a></li>
    </ol>
  </li>
  <li><a href="#ReadingPrefs"></a>
    <ol>
      <li><a href="#Listening"></a></li>
    </ol>
  </li>
  <li><a href="#NetworkUsage"></a></li>
  <li><a href="#Custom"></a>
    <ol>
      <li><a href="#CustomSelected"></a></li>
      <li><a href="#CustomSave"></a></li>
      <li><a href="#CustomInitialize"></a></li>
      <li><a href="#CustomDefault"></a></li>
      <li><a href="#CustomSaveState"></a></li>
    </ol>
  </li>
</ol>

<h2></h2>
<ol>
  <li>{@link android.preference.Preference}</li>
  <li>{@link android.preference.PreferenceActivity}</li>
  <li>{@link android.preference.PreferenceFragment}</li>
</ol>


<h2></h2>
<ol>
  <li><a href="{@docRoot}design/patterns/settings.html"></a></li>
</ol>
</div>
</div>


<p>

</p>

<p>
Android  {@link android.preference.Preference} API
 Android
{@link android.preference.Preference} API </p>

<div class="note design">
<p><strong></strong></p>
  <p><a href="{@docRoot}design/patterns/settings.html"></a></p>
</div>


<img src="{@docRoot}images/ui/settings/settings.png" alt="" width="435" />
<p class="img-caption"><strong> 1. </strong> Android
 {@link android.preference.Preference}
</p>


<h2 id="Overview"></h2>

<p> XML
{@link android.preference.Preference}
 {@link android.view.View} </p>

<p>{@link android.preference.Preference}
 {@link android.preference.Preference}
UI {@link
android.preference.CheckBoxPreference} {@link
android.preference.ListPreference} </p>

<p> {@link android.preference.Preference}
{@link android.content.SharedPreferences}

{@link android.content.SharedPreferences}
{@link android.content.SharedPreferences}
</p>

<p> {@link android.content.SharedPreferences}
</p>

<ul>
  <li></li>
  <li></li>
  <li></li>
  <li></li>
  <li></li>
  <li> {@link java.util.Set}</li>
</ul>

<p> UI  {@link android.preference.Preference}

{@link android.view.View}  {@link android.app.Activity}
{@link android.app.Fragment} </p>

<ul>
  <li> 3.0API  10  Android  Activity
{@link android.preference.PreferenceActivity} </li>
  <li> Android 3.0
{@link android.app.Activity} {@link android.preference.PreferenceFragment}
{@link android.preference.PreferenceActivity}
</li>
</ul>

<p><a href="#Activity"> Activity</a><a href="#Fragment"></a>
 {@link android.preference.PreferenceActivity}  {@link
android.preference.PreferenceFragment} </p>


<h3 id="SettingTypes"></h3>

<p> {@link
android.preference.Preference}

 1
 {@link
android.preference.Preference} </p>

<p></p>

<dl>
  <dt>{@link android.preference.CheckBoxPreference}</dt>
  <dd>
<code>true</code></dd>

  <dt>{@link android.preference.ListPreference}</dt>
  <dd>
</dd>

  <dt>{@link android.preference.EditTextPreference}</dt>
  <dd> {@link android.widget.EditText}  {@link
java.lang.String}</dd>
</dl>

<p> {@link android.preference.Preference}
</p>

<p>
 {@link
android.preference.Preference}
{@link android.preference.Preference} <a href="#Custom"></a></p>


<h2 id="DefiningPrefs"> XML </h2>

<p> {@link android.preference.Preference}
 {@link android.preference.Preference}
 XML  XML

</p>

<p> {@link android.preference.Preference}  {@code &lt;CheckBoxPreference&gt;} XML
</p>

<p> XML  {@code res/xml/}
{@code preferences.xml}
{@link android.preference.PreferenceScreen}
</p>

<p class="note"><strong></strong>
XML </p>

<p>XML  {@link android.preference.PreferenceScreen
&lt;PreferenceScreen&gt;}  {@link
android.preference.Preference}
{@link android.preference.PreferenceScreen &lt;PreferenceScreen&gt;}
</p>

<p></p>

<pre>
&lt;?xml version="1.0" encoding="utf-8"?>
&lt;PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    &lt;CheckBoxPreference
        android:key="pref_sync"
        android:title="@string/pref_sync"
        android:summary="@string/pref_sync_summ"
        android:defaultValue="true" />
    &lt;ListPreference
        android:dependency="pref_sync"
        android:key="pref_syncConnectionType"
        android:title="@string/pref_syncConnectionType"
        android:dialogTitle="@string/pref_syncConnectionType"
        android:entries="@array/pref_syncConnectionTypes_entries"
        android:entryValues="@array/pref_syncConnectionTypes_values"
        android:defaultValue="@string/pref_syncConnectionTypes_default" />
&lt;/PreferenceScreen>
</pre>

<p> {@link android.preference.CheckBoxPreference}  {@link
android.preference.ListPreference}</p>

<dl>
  <dt>{@code android:key}</dt>
  <dd>
{@link
android.content.SharedPreferences}
  <p>
{@link android.preference.PreferenceCategory} {@link android.preference.PreferenceScreen}
{@link android.content.Intent} <a href="#Intents">{@code &lt;intent&gt;}</a>  {@link android.app.Fragment} <a href="{@docRoot}reference/android/preference/Preference.html#attr_android:fragment">{@code
android:fragment}</a> <em></em></p>
  </dd>
  <dt>{@code android:title}</dt>
  <dd></dd>
  <dt>{@code android:defaultValue}</dt>
  <dd> {@link
android.content.SharedPreferences}
</dd>
</dl>

<p> {@link
android.preference.Preference}</p>


<div class="figure" style="width:300px">
  <img src="{@docRoot}images/ui/settings/settings-titles.png" alt="" />
  <p class="img-caption"><strong> 2. </strong>
 <br/><b>1.</b> {@link
android.preference.PreferenceCategory &lt;PreferenceCategory&gt;}  <br/><b>2.</b>
{@code android:title} </p>
</div>


<p> 10

</p>


<h3 id="Groups"></h3>

<p> 10


</p>

<ul>
  <li><a href="#Titles"></a></li>
  <li><a href="#Subscreens"></a></li>
</ul>

<p> Android <a href="{@docRoot}design/patterns/settings.html"></a>

</p>


<h4 id="Titles"></h4>

<p> 2
{@link android.preference.Preference}  {@link
android.preference.PreferenceCategory} </p>

<p></p>

<pre>
&lt;PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    &lt;PreferenceCategory
        android:title="&#64;string/pref_sms_storage_title"
        android:key="pref_key_storage_settings">
        &lt;CheckBoxPreference
            android:key="pref_key_auto_delete"
            android:summary="&#64;string/pref_summary_auto_delete"
            android:title="&#64;string/pref_title_auto_delete"
            android:defaultValue="false"... />
        &lt;Preference
            android:key="pref_key_sms_delete_limit"
            android:dependency="pref_key_auto_delete"
            android:summary="&#64;string/pref_summary_delete_limit"
            android:title="&#64;string/pref_title_sms_delete"... />
        &lt;Preference
            android:key="pref_key_mms_delete_limit"
            android:dependency="pref_key_auto_delete"
            android:summary="&#64;string/pref_summary_delete_limit"
            android:title="&#64;string/pref_title_mms_delete" ... />
    &lt;/PreferenceCategory>
    ...
&lt;/PreferenceScreen>
</pre>


<h4 id="Subscreens"></h4>

<p> 3
{@link android.preference.Preference}  {@link
android.preference.PreferenceScreen} </p>

<img src="{@docRoot}images/ui/settings/settings-subscreen.png" alt="" />
<p class="img-caption"><strong> 3. </strong>{@code
&lt;PreferenceScreen&gt;}
</p>

<p></p>

<pre>
&lt;PreferenceScreen  xmlns:android="http://schemas.android.com/apk/res/android">
    &lt;!-- opens a subscreen of settings -->
    &lt;PreferenceScreen
        android:key="button_voicemail_category_key"
        android:title="&#64;string/voicemail"
        android:persistent="false">
        &lt;ListPreference
            android:key="button_voicemail_provider_key"
            android:title="&#64;string/voicemail_provider" ... />
        &lt;!-- opens another nested subscreen -->
        &lt;PreferenceScreen
            android:key="button_voicemail_setting_key"
            android:title="&#64;string/voicemail_settings"
            android:persistent="false">
            ...
        &lt;/PreferenceScreen>
        &lt;RingtonePreference
            android:key="button_voicemail_ringtone_key"
            android:title="&#64;string/voicemail_ringtone_title"
            android:ringtoneType="notification" ... />
        ...
    &lt;/PreferenceScreen>
    ...
&lt;/PreferenceScreen>
</pre>


<h3 id="Intents"> Intent </h3>

<p> Activity Web
 {@link
android.content.Intent}{@code &lt;intent&gt;}
 {@code &lt;Preference&gt;} </p>

<p></p>

<pre>
&lt;Preference android:title="@string/prefs_web_page" >
    &lt;intent android:action="android.intent.action.VIEW"
            android:data="http://www.example.com" />
&lt;/Preference>
</pre>

<p> Intent</p>

<dl>
  <dt>{@code android:action}</dt>
    <dd> {@link android.content.Intent#setAction setAction()}
</dd>
  <dt>{@code android:data}</dt>
    <dd> {@link android.content.Intent#setData setData()} </dd>
  <dt>{@code android:mimeType}</dt>
    <dd> MIME  {@link android.content.Intent#setType setType()}
</dd>
  <dt>{@code android:targetClass}</dt>
    <dd> {@link android.content.Intent#setComponent
setComponent()} </dd>
  <dt>{@code android:targetPackage}</dt>
    <dd> {@link
android.content.Intent#setComponent setComponent()} </dd>
</dl>


<h2 id="Activity"> Activity</h2>

<p> Activity  {@link
android.preference.PreferenceActivity}  {@link
android.app.Activity}  {@link
android.preference.Preference} {@link android.preference.PreferenceActivity}
 {@link
android.preference.Preference} </p>

<p class="note"><strong></strong> Android 3.0
 {@link android.preference.PreferenceFragment}<a href="#Fragment"></a>
</p>

<p> {@link
android.preference.PreferenceActivity#onCreate onCreate()}  {@link
android.preference.PreferenceActivity#addPreferencesFromResource addPreferencesFromResource()}
XML  Activity
{@link android.preference.PreferenceActivity} </p>

<pre>
public class SettingsActivity extends PreferenceActivity {
    &#64;Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences);
    }
}
</pre>

<p> {@link android.content.SharedPreferences}


{@link android.content.SharedPreferences}
<a href="#ReadingPrefs"></a>
</p>


<h2 id="Fragment"></h2>

<p> Android 3.0API  11 {@link
android.preference.PreferenceFragment}  {@link android.preference.Preference}
 {@link android.preference.PreferenceFragment}  Activity
{@link android.preference.PreferenceActivity}</p>

<p> Activity  Activity<a href="{@docRoot}guide/components/fragments.html"></a>

 {@link
android.preference.PreferenceFragment}  {@link
android.preference.PreferenceActivity}</p>

<p>{@link android.preference.PreferenceFragment}
{@link android.preference.PreferenceFragment#onCreate onCreate()}
{@link android.preference.PreferenceFragment#addPreferencesFromResource
addPreferencesFromResource()} </p>

<pre>
public static class SettingsFragment extends PreferenceFragment {
    &#64;Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Load the preferences from an XML resource
        addPreferencesFromResource(R.xml.preferences);
    }
    ...
}
</pre>

<p>
{@link android.app.Fragment}  {@link android.app.Activity}</p>

<pre>
public class SettingsActivity extends Activity {
    &#64;Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Display the fragment as the main content.
        getFragmentManager().beginTransaction()
                .replace(android.R.id.content, new SettingsFragment())
                .commit();
    }
}
</pre>

<p class="note"><strong></strong>{@link android.preference.PreferenceFragment}
{@link android.content.Context}  {@link android.content.Context}
 {@link android.app.Fragment#getActivity()} Activity
{@link android.app.Fragment#getActivity()}
{@link
android.app.Fragment#getActivity()}  null</p>


<h2 id="Defaults"></h2>

<p> {@link android.preference.Preference}

{@link android.content.SharedPreferences}
</p>

<p> {@code android:defaultValue}  XML  {@link
android.preference.Preference}

{@link android.preference.Preference}
</p>

<pre>
&lt;!-- default value is a boolean -->
&lt;CheckBoxPreference
    android:defaultValue="true"
    ... />

&lt;!-- default value is a string -->
&lt;ListPreference
    android:defaultValue="@string/pref_syncConnectionTypes_default"
    ... />
</pre>

<p> Activity Activity {@link android.app.Activity#onCreate onCreate()}
 {@link android.preference.PreferenceManager#setDefaultValues
setDefaultValues()}
</p>

<pre>
PreferenceManager.setDefaultValues(this, R.xml.advanced_preferences, false);
</pre>

<p>
{@link android.app.Activity#onCreate onCreate()}

</p>

<p></p>
<ul>
  <li> {@link android.content.Context}</li>
  <li> XML  ID</li>
  <li>
<p> <code>false</code>
{@link android.preference.PreferenceManager#KEY_HAS_SET_DEFAULT_VALUES}
false </p></li>
</ul>

<p>
<code>false</code> Activity

<code>true</code></p>


<h2 id="PreferenceHeaders"></h2>

<p><a href="#Subscreens"></a> 4  5

 Android 3.0
Android 3.0
{@link android.preference.PreferenceScreen} </p>

<p></p>
<ol>
  <li> {@link
android.preference.PreferenceFragment}  XML
</li>
  <li> XML
</li>
  <li> {@link android.preference.PreferenceActivity} </li>
  <li> {@link
android.preference.PreferenceActivity#onBuildHeaders onBuildHeaders()}
</li>
</ol>

<p>{@link android.preference.PreferenceActivity}
 4 </p>

<p> 3.0  Android
{@link android.preference.PreferenceFragment}
<a href="#BackCompatHeaders"></a>

</p>

<img src="{@docRoot}images/ui/settings/settings-headers-tablet.png" alt="" />
<p class="img-caption"><strong> 4. </strong> <br/><b>1.</b>
XML  <br/><b>2.</b>
{@link android.preference.PreferenceFragment} {@code &lt;header&gt;}
</p>

<img src="{@docRoot}images/ui/settings/settings-headers-handset.png" alt="" />
<p class="img-caption"><strong> 5. </strong>
{@link android.preference.PreferenceFragment}
</p>


<h3 id="CreateHeaders" style="clear:left"></h3>

<p> {@code &lt;preference-headers&gt;}  {@code &lt;header&gt;}
</p>

<pre>
&lt;?xml version="1.0" encoding="utf-8"?>
&lt;preference-headers xmlns:android="http://schemas.android.com/apk/res/android">
    &lt;header
        android:fragment="com.example.prefs.SettingsActivity$SettingsFragmentOne"
        android:title="@string/prefs_category_one"
        android:summary="@string/prefs_summ_category_one" />
    &lt;header
        android:fragment="com.example.prefs.SettingsActivity$SettingsFragmentTwo"
        android:title="@string/prefs_category_two"
        android:summary="@string/prefs_summ_category_two" >
        &lt;!-- key/value pairs can be included as arguments for the fragment. -->
        &lt;extra android:name="someKey" android:value="someHeaderValue" />
    &lt;/header>
&lt;/preference-headers>
</pre>

<p> {@code android:fragment}  {@link
android.preference.PreferenceFragment} </p>

<p>{@code &lt;extras&gt;}  {@link
android.os.Bundle}  {@link
android.app.Fragment#getArguments()}
{@link
android.preference.PreferenceFragment}
 XML </p>

<p>
{@code "settings"}  {@code &lt;extra&gt;} </p>

<pre>
public static class SettingsFragment extends PreferenceFragment {
    &#64;Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        String settings = getArguments().getString("settings");
        if ("notifications".equals(settings)) {
            addPreferencesFromResource(R.xml.settings_wifi);
        } else if ("sync".equals(settings)) {
            addPreferencesFromResource(R.xml.settings_sync);
        }
    }
}
</pre>


<h3 id="DisplayHeaders"></h3>

<p> {@link
android.preference.PreferenceActivity#onBuildHeaders onBuildHeaders()}
{@link android.preference.PreferenceActivity#loadHeadersFromResource
loadHeadersFromResource()}</p>

<pre>
public class SettingsActivity extends PreferenceActivity {
    &#64;Override
    public void onBuildHeaders(List&lt;Header> target) {
        loadHeadersFromResource(R.xml.preference_headers, target);
    }
}
</pre>

<p> {@link
android.preference.PreferenceFragment}</p>

<p class="note"><strong></strong>{@link
android.preference.PreferenceActivity}  {@link
android.preference.PreferenceActivity#onCreate onCreate()}
 Activity </p>


<h3 id="BackCompatHeaders"></h3>

<p> 3.0  Android
 Android 3.0
 {@link android.preference.Preference
&lt;Preference&gt;}  XML  Android
 </p>

<p> {@link
android.preference.Preference &lt;Preference&gt;}  {@link android.preference.PreferenceActivity}  {@link android.content.Intent} XML
{@link android.preference.PreferenceScreen}
</p>

<p> Android 3.0
 XML  ({@code res/xml/preference_headers.xml})</p>

<pre>
&lt;preference-headers xmlns:android="http://schemas.android.com/apk/res/android">
    &lt;header
        android:fragment="com.example.prefs.SettingsFragmentOne"
        android:title="@string/prefs_category_one"
        android:summary="@string/prefs_summ_category_one" />
    &lt;header
        android:fragment="com.example.prefs.SettingsFragmentTwo"
        android:title="@string/prefs_category_two"
        android:summary="@string/prefs_summ_category_two" />
&lt;/preference-headers>
</pre>

<p>
Android 3.0  ({@code res/xml/preference_headers_legacy.xml})</p>

<pre>
&lt;PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    &lt;Preference
        android:title="@string/prefs_category_one"
        android:summary="@string/prefs_summ_category_one"  >
        &lt;intent
            android:targetPackage="com.example.prefs"
            android:targetClass="com.example.prefs.SettingsActivity"
            android:action="com.example.prefs.PREFS_ONE" />
    &lt;/Preference>
    &lt;Preference
        android:title="@string/prefs_category_two"
        android:summary="@string/prefs_summ_category_two" >
        &lt;intent
            android:targetPackage="com.example.prefs"
            android:targetClass="com.example.prefs.SettingsActivity"
            android:action="com.example.prefs.PREFS_TWO" />
    &lt;/Preference>
&lt;/PreferenceScreen>
</pre>

<p> Android 3.0  {@code &lt;preference-headers&gt;}  Androd 3.0  {@link
android.preference.PreferenceActivity}
 {@link android.preference.PreferenceActivity#onBuildHeaders onBuildHeaders()}
({@code preference_headers_legacy.xml}) Android
 Android 3.0 ({@link
android.os.Build.VERSION_CODES#HONEYCOMB}) {@link
android.preference.PreferenceActivity#addPreferencesFromResource addPreferencesFromResource()}
</p>

<pre>
&#64;Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ...

    if (Build.VERSION.SDK_INT &lt; Build.VERSION_CODES.HONEYCOMB) {
        // Load the legacy preferences headers
        addPreferencesFromResource(R.xml.preference_headers_legacy);
    }
}

// Called only on Honeycomb and later
&#64;Override
public void onBuildHeaders(List&lt;Header> target) {
   loadHeadersFromResource(R.xml.preference_headers, target);
}
</pre>

<p> Activity
{@link android.content.Intent} Intent  XML  {@code &lt;intent&gt;}
</p>

<pre>
final static String ACTION_PREFS_ONE = "com.example.prefs.PREFS_ONE";
...

&#64;Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    String action = getIntent().getAction();
    if (action != null &amp;&amp; action.equals(ACTION_PREFS_ONE)) {
        addPreferencesFromResource(R.xml.preferences);
    }
    ...

    else if (Build.VERSION.SDK_INT &lt; Build.VERSION_CODES.HONEYCOMB) {
        // Load the legacy preferences headers
        addPreferencesFromResource(R.xml.preference_headers_legacy);
    }
}
</pre>

<p> {@link
android.preference.PreferenceActivity#addPreferencesFromResource addPreferencesFromResource()}

else-if </p>


<h2 id="ReadingPrefs"></h2>

<p>
{@link
android.preference.PreferenceManager#getDefaultSharedPreferences
PreferenceManager.getDefaultSharedPreferences()}  {@link
android.content.SharedPreferences}
{@link
android.preference.PreferenceActivity}  {@link android.preference.Preference} </p>

<p> Activity
</p>

<pre>
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
String syncConnPref = sharedPref.getString(SettingsActivity.KEY_PREF_SYNC_CONN, "");
</pre>


<h3 id="Listening"></h3>

<p>

{@link android.content.SharedPreferences.OnSharedPreferenceChangeListener
SharedPreference.OnSharedPreferenceChangeListener}  {@link
android.content.SharedPreferences#registerOnSharedPreferenceChangeListener
registerOnSharedPreferenceChangeListener()}
{@link android.content.SharedPreferences} </p>

<p> {@link
android.content.SharedPreferences.OnSharedPreferenceChangeListener#onSharedPreferenceChanged
onSharedPreferenceChanged()}
 Activity </p>

<pre>
public class SettingsActivity extends PreferenceActivity
                              implements OnSharedPreferenceChangeListener {
    public static final String KEY_PREF_SYNC_CONN = "pref_syncConnectionType";
    ...

    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
        String key) {
        if (key.equals(KEY_PREF_SYNC_CONN)) {
            Preference connectionPref = findPreference(key);
            // Set summary to be the user-description for the selected value
            connectionPref.setSummary(sharedPreferences.getString(key, ""));
        }
    }
}
</pre>

<p>
{@link android.preference.PreferenceActivity#findPreference findPreference()}
{@link android.preference.Preference}
 {@link
android.preference.ListPreference}
5 Sleep {@link
android.preference.Preference#setSummary setSummary()}</p>

<p class="note"><strong></strong> Android <a href="{@docRoot}design/patterns/settings.html"></a>
{@link android.preference.ListPreference}
</p>

<p> Activity
{@link
android.app.Activity#onResume}  {@link android.app.Activity#onPause}  {@link android.content.SharedPreferences.OnSharedPreferenceChangeListener}</p>

<pre>
&#64;Override
protected void onResume() {
    super.onResume();
    getPreferenceScreen().getSharedPreferences()
            .registerOnSharedPreferenceChangeListener(this);
}

&#64;Override
protected void onPause() {
    super.onPause();
    getPreferenceScreen().getSharedPreferences()
            .unregisterOnSharedPreferenceChangeListener(this);
}
</pre>

<p class="caution"><strong></strong> {@link
android.content.SharedPreferences#registerOnSharedPreferenceChangeListener
registerOnSharedPreferenceChangeListener()}


</p>

<p>

</p>

<pre>
prefs.registerOnSharedPreferenceChangeListener(
  // Bad! The listener is subject to garbage collection!
  new SharedPreferences.OnSharedPreferenceChangeListener() {
  public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
    // listener implementation
  }
});
</pre>

<p>
</p>

<pre>
SharedPreferences.OnSharedPreferenceChangeListener listener =
    new SharedPreferences.OnSharedPreferenceChangeListener() {
  public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
    // listener implementation
  }
};
prefs.registerOnSharedPreferenceChangeListener(listener);
</pre>

<h2 id="NetworkUsage"></h2>


<p> Android 4.0


<p>

<p>
Wi-Fi /


</p>

<p> {@link android.preference.PreferenceActivity}
 {@link
android.content.Intent#ACTION_MANAGE_NETWORK_USAGE}  Intent </p>

<pre>
&lt;activity android:name="SettingsActivity" ... >
    &lt;intent-filter>
       &lt;action android:name="android.intent.action.MANAGE_NETWORK_USAGE" />
       &lt;category android:name="android.intent.category.DEFAULT" />
    &lt;/intent-filter>
&lt;/activity>
</pre>

<p> Intent
 Activity
{@link android.preference.PreferenceActivity}

<em></em></p>


<h2 id="Custom"></h2>

<p>Android
{@link android.preference.Preference}
 UI

{@link android.preference.Preference} </p>

<p> {@link android.preference.Preference}
</p>

<ul>
  <li></li>
  <li></li>
  <li>
{@link android.preference.Preference}</li>
  <li></li>
  <li> {@link android.preference.Preference}
 UI</li>
</ul>

<p></p>


<h3 id="CustomSelected"></h3>

  <p> {@link android.preference.Preference}
{@link android.preference.Preference#onClick()}
 {@link android.preference.DialogPreference}
 {@link
android.preference.DialogPreference}  {@link
android.preference.DialogPreference#setDialogLayoutResource setDialogLayoutResourcs()}
</p>

  <p> {@link
android.preference.DialogPreference}
</p>

<pre>
public class NumberPickerPreference extends DialogPreference {
    public NumberPickerPreference(Context context, AttributeSet attrs) {
        super(context, attrs);

        setDialogLayoutResource(R.layout.numberpicker_dialog);
        setPositiveButtonText(android.R.string.ok);
        setNegativeButtonText(android.R.string.cancel);

        setDialogIcon(null);
    }
    ...
}
</pre>


<h3 id="CustomSave"></h3>

<p>
{@link android.preference.Preference#persistBoolean persistBoolean()} {@link
android.preference.Preference}  {@code persist*()}  {@link
android.preference.Preference#persistInt persistInt()}</p>

<p class="note"><strong></strong> {@link android.preference.Preference}

{@link android.preference.Preference}  {@code persist*()} </p>

<p> {@link
android.preference.Preference}
{@link
android.preference.DialogPreference}</p>

<p> {@link android.preference.DialogPreference}  {@link
android.preference.DialogPreference#onDialogClosed onDialogClosed()}
<code>true</code>

</p>

<pre>
&#64;Override
protected void onDialogClosed(boolean positiveResult) {
    // When the user selects "OK", persist the new value
    if (positiveResult) {
        persistInt(mNewValue);
    }
}
</pre>

<p><code>mNewValue</code>
 {@link android.preference.Preference#persistInt persistInt()}
{@link android.content.SharedPreferences}
{@link android.preference.Preference}  XML </p>


<h3 id="CustomInitialize"></h3>

<p> {@link android.preference.Preference}
{@link android.preference.Preference#onSetInitialValue onSetInitialValue()}

</p>

<p>{@link android.preference.Preference#onSetInitialValue onSetInitialValue()}
 (<code>restorePersistedValue</code>)
 <code>true</code>
{@link
android.preference.Preference}  {@code getPersisted*()}  {@link
android.preference.Preference#getPersistedInt getPersistedInt()} UI

</p>

<p> <code>restorePersistedValue</code>
<code>false</code></p>

<pre>
&#64;Override
protected void onSetInitialValue(boolean restorePersistedValue, Object defaultValue) {
    if (restorePersistedValue) {
        // Restore existing state
        mCurrentValue = this.getPersistedInt(DEFAULT_VALUE);
    } else {
        // Set default state from the XML attribute
        mCurrentValue = (Integer) defaultValue;
        persistInt(mCurrentValue);
    }
}
</pre>

<p> {@code getPersisted*()}

{@link
android.preference.Preference#getPersistedInt getPersistedInt()} </p>

<p class="caution"><strong></strong><strong></strong>
<code>defaultValue</code>  {@code getPersisted*()}
<code>restorePersistedValue</code>  <code>true</code>  null</p>


<h3 id="CustomDefault"></h3>

<p> {@link android.preference.Preference}
 {@code android:defaultValue}
 {@link android.preference.Preference#onGetDefaultValue
onGetDefaultValue()} {@link
android.content.SharedPreferences}
</p>

<pre>
&#64;Override
protected Object onGetDefaultValue(TypedArray a, int index) {
    return a.getInteger(index, DEFAULT_VALUE);
}
</pre>

<p>
{@code android:defaultValue}

</p>


<h3 id="CustomSaveState"></h3>

<p> {@link android.view.View}
 Activity {@link android.preference.Preference}

{@link android.preference.Preference}
{@link android.preference.Preference#onSaveInstanceState
onSaveInstanceState()}  {@link
android.preference.Preference#onRestoreInstanceState onRestoreInstanceState()}</p>

<p>{@link android.preference.Preference}
{@link android.os.Parcelable} Android {@link
android.preference.Preference.BaseSavedState}
</p>

<p> {@link android.preference.Preference}
{@link android.preference.Preference.BaseSavedState}
{@link android.preference.Preference.BaseSavedState#CREATOR}
</p>

<p> {@link android.preference.Preference}

{@code value} </p>

<pre>
private static class SavedState extends BaseSavedState {
    // Member that holds the setting's value
    // Change this data type to match the type saved by your Preference
    int value;

    public SavedState(Parcelable superState) {
        super(superState);
    }

    public SavedState(Parcel source) {
        super(source);
        // Get the current preference's value
        value = source.readInt();  // Change this to read the appropriate data type
    }

    &#64;Override
    public void writeToParcel(Parcel dest, int flags) {
        super.writeToParcel(dest, flags);
        // Write the preference's value
        dest.writeInt(value);  // Change this to write the appropriate data type
    }

    // Standard creator object using an instance of this class
    public static final Parcelable.Creator&lt;SavedState> CREATOR =
            new Parcelable.Creator&lt;SavedState>() {

        public SavedState createFromParcel(Parcel in) {
            return new SavedState(in);
        }

        public SavedState[] newArray(int size) {
            return new SavedState[size];
        }
    };
}
</pre>

<p> {@link android.preference.Preference.BaseSavedState}
 {@link android.preference.Preference}

{@link android.preference.Preference}  {@link android.preference.Preference#onSaveInstanceState
onSaveInstanceState()}  {@link
android.preference.Preference#onRestoreInstanceState onRestoreInstanceState()} </p>

<p></p>

<pre>
&#64;Override
protected Parcelable onSaveInstanceState() {
    final Parcelable superState = super.onSaveInstanceState();
    // Check whether this Preference is persistent (continually saved)
    if (isPersistent()) {
        // No need to save instance state since it's persistent,
        // use superclass state
        return superState;
    }

    // Create instance of custom BaseSavedState
    final SavedState myState = new SavedState(superState);
    // Set the state's value with the class member that holds current
    // setting value
    myState.value = mNewValue;
    return myState;
}

&#64;Override
protected void onRestoreInstanceState(Parcelable state) {
    // Check whether we saved the state in onSaveInstanceState
    if (state == null || !state.getClass().equals(SavedState.class)) {
        // Didn't save the state, so call superclass
        super.onRestoreInstanceState(state);
        return;
    }

    // Cast state to custom BaseSavedState and pass to superclass
    SavedState myState = (SavedState) state;
    super.onRestoreInstanceState(myState.getSuperState());

    // Set this Preference's widget to reflect the restored state
    mNumberPicker.setValue(myState.value);
}
</pre>