topics/ui/settings.jd

page.title=
page.tags=preference,preferenceactivity,preferencefragment

@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"></a></li>
    </ol>
  </li>
  <li><a href="#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">Settings design guide</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 SMS
{@link android.preference.Preference}
</p>


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

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

</p>

<p>1  {@link android.preference.Preference} 1
 {@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>Boolean</li>
  <li>Float</li>
  <li>Int</li>
  <li>Long</li>
  <li>String</li>
  <li>String {@link java.util.Set}</li>
</ul>

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


</p>

<ul>
  <li> 3.0  AndroidAPI  10 {@link android.preference.PreferenceActivity}
</li>
  <li>Android 3.0  {@link android.preference.PreferenceFragment}  {@link android.app.Activity} {@link android.preference.PreferenceActivity}  2


</li>
</ul>

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

</p>


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

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


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

<p></p>

<dl>
  <dt>{@link android.preference.CheckBoxPreference}</dt>
  <dd>Boolean <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  XML

</p>

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

<p> XML {@code res/xml/}  XML {@code preferences.xml}
 {@link android.preference.PreferenceScreen}  1

</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;}  1

</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}
 3 </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
1

 2 </p>

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

<p> 1 Android Design <a href="{@docRoot}design/patterns/settings.html">Settings</a>

</p>


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

<p> 2. {@link android.preference.Preference}  1  {@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"></h3>

<p>
  {@link android.content.Intent}  {@code &lt;Preference&gt;}  {@code &lt;intent&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></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>{@link android.content.Intent#setType setType()}  MIME
</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"> </h2>

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

{@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

{@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}  &mdash; {@link android.preference.PreferenceActivity}
</p>

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

 {@link android.preference.PreferenceActivity} {@link android.preference.PreferenceFragment}

</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()}
{@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>  {@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> 3 </p>
<ul>
  <li> {@link android.content.Context}</li>
  <li> XML  ID</li>
  <li>
<p><code>false</code>  1  {@link android.preference.PreferenceManager#KEY_HAS_SET_DEFAULT_VALUES}  false

</p></li>
</ul>

<p> 3  <code>false</code>

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


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

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

 Android 3.0  {@link android.preference.PreferenceScreen} Android 3.0

</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  2
</p>

<p> 3.0  Android 3.0 {@link android.preference.PreferenceFragment}  3.0  2 <a href="#BackCompatHeaders"> </a>


</p>

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

</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  1


</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()}


</p>


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

<p> Android 3.0 3.0  2
3.0  Android   {@link android.preference.Preference &lt;Preference&gt;}  XML


</p>

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


</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>{@code &lt;preference-headers&gt;}  Android 3.0 Android 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> {@link android.content.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()}  1 else if 1


</p>


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

<p> {@link android.preference.PreferenceManager#getDefaultSharedPreferences PreferenceManager.getDefaultSharedPreferences()}


{@link android.preference.PreferenceActivity}  {@link android.preference.Preference}  {@link android.content.SharedPreferences}


</p>

<p> 1
</p>

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


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

<p>
 1  {@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()} 1


</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}  {@link android.preference.Preference#setSummary setSummary()}  5.


</p>

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

</p>

<p>{@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}

</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>
[<em>View application settings</em>] {@link android.preference.PreferenceActivity}


</p>


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

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


{@link android.preference.Preference}  1
</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#persistInt persistInt()} {@link android.preference.Preference}  {@code persist*()}


</p>

<p class="note"><strong>:</strong>  {@link android.preference.Preference} 1  {@link android.preference.Preference}  {@code persist*()}

</p>

<p> {@link android.preference.Preference}
{@link android.preference.DialogPreference}  [OK]

</p>

<p>{@link android.preference.DialogPreference}  {@link android.preference.DialogPreference#onDialogClosed onDialogClosed()}
Positive &mdash;  <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>  1
{@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> 2
</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> <code>defaultValue</code> <code>restorePersistedValue</code>  <code>true</code>  null {@code getPersisted*()} <strong></strong>

</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} {@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>