如here所述，我正在将PreferenceFragment子类化并在Activity中显示它。该文档解释了如何监听首选项更改here，但前提是您继承了PreferenceActivity。由于我不这样做，我如何监听偏好变化？
我已经尝试在我的PreferenceFragment中实现OnSharedPreferenceChangeListener但它似乎不起作用（onSharedPreferenceChanged似乎永远不会被调用）。
到目前为止这是我的代码：
settings activity.Java
public class SettingsActivity extends Activity
{
@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();
}
}
settings fragment.Java
public class SettingsFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener
{
public static final String KEY_PREF_EXERCISES = "pref_number_of_exercises";
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.preferences);
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key)
{
//IT NEVER GETS IN HERE!
if (key.equals(KEY_PREF_EXERCISES))
{
// Set summary to be the user-description for the selected value
Preference exercisesPref = findPreference(key);
exercisesPref.setSummary(sharedPreferences.getString(key, ""));
}
}
}
的preferences.xml
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
<EditTextPreference
android:defaultValue="15"
android:enabled="true"
android:key="pref_number_of_exercises"
android:numeric="integer"
android:title="Number of exercises" />
</PreferenceScreen>
另外，PreferenceFragment是否是正确的地方，可以监听偏好变化，还是应该在Activity中进行？
我相信你只需要在你的Listener注册/取消注册PreferenceFragment就可以了。
@Override
public void onResume() {
super.onResume();
getPreferenceManager().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
}
@Override
public void onPause() {
getPreferenceManager().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
super.onPause();
}
根据您的要求，您可能不需要使用监听器。对首选项的更改会自动提交给SharedPreferences。
antew的解决方案效果很好，在这里您可以看到Android v11以后的完整首选项活动：
import android.app.Activity;
import android.content.SharedPreferences;
import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
import android.os.Bundle;
import android.preference.ListPreference;
import android.preference.PreferenceFragment;
public class UserPreferencesV11 extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Display the fragment as the main content.
getFragmentManager().beginTransaction().replace(android.R.id.content,
new PrefsFragment()).commit();
}
public static class PrefsFragment extends PreferenceFragment implements OnSharedPreferenceChangeListener {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Load the preferences from an XML resource
addPreferencesFromResource(R.xml.preferences);
// set texts correctly
onSharedPreferenceChanged(null, "");
}
@Override
public void onResume() {
super.onResume();
// Set up a listener whenever a key changes
getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
}
@Override
public void onPause() {
super.onPause();
// Set up a listener whenever a key changes
getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
// just update all
ListPreference lp = (ListPreference) findPreference(PREF_YOUR_KEY);
lp.setSummary("dummy"); // required or will not update
lp.setSummary(getString(R.string.pref_yourKey) + ": %s");
}
}
}
所有其他答案都是正确的。但我更喜欢这种替代方案，因为你立即拥有导致改变的Preference实例。
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Preference pref = findPreference(getString(R.string.key_of_pref));
pref.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
@Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
// do whatever you want with new value
// true to update the state of the Preference with the new value
// in case you want to disallow the change return false
return true;
}
});
}
这对我有用，来自PreferenceFragment.onCreate（）
OnSharedPreferenceChangeListener listener =
new SharedPreferences.OnSharedPreferenceChangeListener()
{
public void onSharedPreferenceChanged(SharedPreferences prefs, String key)
{
showDialog();
}
};
这是一种方法，可以避免任何潜在的内存泄漏：
@Override
public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
addPreferencesFromResource(R.xml.pref_movies);
SharedPreferences sharedPreferences = getPreferenceScreen().getSharedPreferences();
//starts live change listener
sharedPreferences.registerOnSharedPreferenceChangeListener(this);
}
@Override
public void onDestroyView () {
super.onDestroyView();
//Unregisters listener here
PreferenceManager.getDefaultSharedPreferences(getContext())
.unregisterOnSharedPreferenceChangeListener(this);
}
另一个完整的例子让你看到整个画面。
public class SettingsActivity extends AppCompatPreferenceActivity {
/**
* A preference value change listener that updates the preference's summary
* to reflect its new value.
*/
private static Preference.OnPreferenceChangeListener
sBindPreferenceSummaryToValueListener =
new Preference.OnPreferenceChangeListener() {
@Override
public boolean onPreferenceChange(Preference preference, Object value) {
String stringValue = value.toString();
if (preference instanceof ListPreference) {
// For list preferences, look up the correct display value in
// the preference's 'entries' list.
ListPreference listPreference = (ListPreference) preference;
int index = listPreference.findIndexOfValue(stringValue);
// Set the summary to reflect the new value.
preference.setSummary(
index >= 0
? listPreference.getEntries()[index]
: null);
} else if (preference instanceof RingtonePreference) {
// For ringtone preferences, look up the correct display value
// using RingtoneManager.
if (TextUtils.isEmpty(stringValue)) {
// Empty values correspond to 'silent' (no ringtone).
preference.setSummary(R.string.pref_ringtone_silent);
} else {
Ringtone ringtone = RingtoneManager.getRingtone(
preference.getContext(), Uri.parse(stringValue));
if (ringtone == null) {
// Clear the summary if there was a lookup error.
preference.setSummary(null);
} else {
// Set the summary to reflect the new ringtone display
// name.
String name = ringtone.getTitle(preference.getContext());
preference.setSummary(name);
}
}
} else {
// For all other preferences, set the summary to the value's
// simple string representation.
preference.setSummary(stringValue);
}
return true;
}
};
/**
* Helper method to determine if the device has an extra-large screen. For
* example, 10" tablets are extra-large.
*/
private static boolean isXLargeTablet(Context context) {
return (context.getResources().getConfiguration().screenLayout
& Configuration.SCREENLAYOUT_SIZE_MASK) >= Configuration.SCREENLAYOUT_SIZE_XLARGE;
}
/**
* Binds a preference's summary to its value. More specifically, when the
* preference's value is changed, its summary (line of text below the
* preference title) is updated to reflect the value. The summary is also
* immediately updated upon calling this method. The exact display format is
* dependent on the type of preference.
*
* @see #sBindPreferenceSummaryToValueListener
*/
private static void bindPreferenceSummaryToValue(Preference preference) {
// Set the listener to watch for value changes.
preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);
// Trigger the listener immediately with the preference's current value.
sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
PreferenceManager
.getDefaultSharedPreferences(preference.getContext())
.getString(preference.getKey(), ""));
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setupActionBar();
}
/**
* Set up the {@link android.app.ActionBar}, if the API is available.
*/
private void setupActionBar() {
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
// Show the Up button in the action bar.
actionBar.setDisplayHomeAsUpEnabled(true);
}
}
@Override
public boolean onMenuItemSelected(int featureId, MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
if (!super.onMenuItemSelected(featureId, item)) {
NavUtils.navigateUpFromSameTask(this);
}
return true;
}
return super.onMenuItemSelected(featureId, item);
}
/**
* {@inheritDoc}
*/
@Override
public boolean onIsMultiPane() {
return isXLargeTablet(this);
}
/**
* {@inheritDoc}
*/
@Override
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public void onBuildHeaders(List<Header> target) {
loadHeadersFromResource(R.xml.pref_headers, target);
}
/**
* This method stops fragment injection in malicious applications.
* Make sure to deny any unknown fragments here.
*/
protected boolean isValidFragment(String fragmentName) {
return PreferenceFragment.class.getName().equals(fragmentName)
|| GPSLocationPreferenceFragment.class.getName().equals(fragmentName)
|| DataSyncPreferenceFragment.class.getName().equals(fragmentName)
|| NotificationPreferenceFragment.class.getName().equals(fragmentName);
}
////////////////// NEW PREFERENCES ////////////////////////////
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static class GPSLocationPreferenceFragment extends PreferenceFragment {
Preference prefGPSServerAddr, prefGPSASDID, prefIsGPSSwitch;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.pref_gps_location);
setHasOptionsMenu(true);
// Bind the summaries of EditText/List/Dialog/Ringtone preferences
// to their values. When their values change, their summaries are
// updated to reflect the new value, per the Android Design
// guidelines.
bindPreferenceSummaryToValue(findPreference("gpsServer_Addr"));
bindPreferenceSummaryToValue(findPreference("gpsASD_ID"));
prefGPSServerAddr = findPreference("gpsServer_Addr");
prefGPSServerAddr.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
@Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
try {
// do whatever you want with new value
}
catch (Exception ex)
{
Log.e("Preferences", ex.getMessage());
}
// true to update the state of the Preference with the new value
// in case you want to disallow the change return false
return true;
}
});
prefGPSASDID = findPreference("gpsASD_ID");
prefGPSASDID.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
@Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
try {
// do whatever you want with new value
}
catch (Exception ex)
{
Log.e("Preferences", ex.getMessage());
}
// true to update the state of the Preference with the new value
// in case you want to disallow the change return false
return true;
}
});
prefIsGPSSwitch = findPreference("isGPS_Switch");
prefIsGPSSwitch.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
@Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
try {
// do whatever you want with new value
}
catch (Exception ex)
{
Log.e("Preferences", ex.getMessage());
}
// true to update the state of the Preference with the new value
// in case you want to disallow the change return false
return true;
}
});
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
boolean tabletSize = getResources().getBoolean(R.bool.isTablet);
if (tabletSize) {
startActivity(new Intent(getActivity(), MainActivity.class));
} else {
startActivity(new Intent(getActivity(), SettingsActivity.class));
}
return true;
}
return super.onOptionsItemSelected(item);
}
}
///////////////////////////////////////////////////////////////
/**
* This fragment shows notification preferences only. It is used when the
* activity is showing a two-pane settings UI.
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static class NotificationPreferenceFragment extends PreferenceFragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.pref_notification);
setHasOptionsMenu(true);
// Bind the summaries of EditText/List/Dialog/Ringtone preferences
// to their values. When their values change, their summaries are
// updated to reflect the new value, per the Android Design
// guidelines.
bindPreferenceSummaryToValue(findPreference("notifications_new_message_ringtone"));
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
boolean tabletSize = getResources().getBoolean(R.bool.isTablet);
if (tabletSize) {
startActivity(new Intent(getActivity(), MainActivity.class));
} else {
startActivity(new Intent(getActivity(), SettingsActivity.class));
}
return true;
}
return super.onOptionsItemSelected(item);
}
}
/**
* This fragment shows data and sync preferences only. It is used when the
* activity is showing a two-pane settings UI.
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public static class DataSyncPreferenceFragment extends PreferenceFragment {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.pref_data_sync);
setHasOptionsMenu(true);
// Bind the summaries of EditText/List/Dialog/Ringtone preferences
// to their values. When their values change, their summaries are
// updated to reflect the new value, per the Android Design
// guidelines.
bindPreferenceSummaryToValue(findPreference("sync_frequency"));
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int id = item.getItemId();
if (id == android.R.id.home) {
boolean tabletSize = getResources().getBoolean(R.bool.isTablet);
if (tabletSize) {
startActivity(new Intent(getActivity(), MainActivity.class));
} else {
startActivity(new Intent(getActivity(), SettingsActivity.class));
}
return true;
}
return super.onOptionsItemSelected(item);
}
}
}
我最近使用PreferenceScreen完成了我自己的Preferences API，所以我想我会贡献我自己的完整示例..这包括将Summary更新为新的/更改的值，以及倾听和对变化作出反应。
PS。回答你的上一个问题：要在Summary初始创建时显示PreferenceScreen的默认值（在值的任何更改之前），您可以直接在android:summary文件中将preferences.xml设置为您选择的值 - 并且然后，一旦Value发生变化，它将使用下面示例中包含的代码自动更新。就个人而言，我使用Preference的简短解释作为我的初始Summary，在我的preferences.xml中设置，然后一旦Value确实第一次改变，它将简单地显示当前的值为Summary从那时起......
无论如何，这是我的完整示例：
SettingsFragment.java
public class SettingsFragment extends PreferenceFragment {
public static final String PREF_NOTIFICATION_MODE = "pref_notificationMode";
private SharedPreferences.OnSharedPreferenceChangeListener preferenceChangeListener;
@Override
public void onCreate (@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.preferences);
final SharedPreferences getPrefs = PreferenceManager.getDefaultSharedPreferences(this.getActivity());
preferenceChangeListener = new SharedPreferences.OnSharedPreferenceChangeListener() {
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
if (key.equals(PREF_NOTIFICATION_MODE)) {
Preference notifModePref = findPreference(key);
notifModePref.setSummary(sharedPreferences.getString(key, ""));
// DO SOMETHING ELSE HERE WHEN (PREF_NOTIFICATION_MODE) IS CHANGED
}
}
};
}
@Override
public void onResume() {
super.onResume();
getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(preferenceChangeListener);
Preference notifModePref = findPreference(PREF_NOTIFICATION_MODE);
notifModePref.setSummary(getPreferenceScreen().getSharedPreferences().getString(PREF_NOTIFICATION_MODE, ""));
}
@Override
public void onPause() {
getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(preferenceChangeListener);
super.onPause();
}
}
我希望这有帮助！ 非常感谢任何积极的反馈，因为我对StackOverflow相当新;） 快乐的编码！
您只需要在onResume()方法中指定指定的Prefernce类。在我的情况下，我使用SwitchPreference类，因此代码将类似于SettingsActivity.class
public static class PrivacyPreferenceFragment extends PreferenceFragment
{
public SwitchPreference switchPreference;
@Override
public void onResume() {
super.onResume();
switchPreference = (SwitchPreference) findPreference("privacy_notice_check");
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.pref_privacy);
setHasOptionsMenu(true);
}
然后在要使用PrefernceFragment值的活动中，只需使用SharedPreference对象调用值并触发它。