[英]How to listen for preference changes within a PreferenceFragment?
如上所述這里,我繼承PreferenceFragment並顯示它的活動中。 該文檔解釋了如何在此處偵聽首選項更改,但前提是您將 PreferenceActivity 子類化。 既然我沒有這樣做,我該如何聽取偏好的變化?
我已經嘗試在我的 PreferenceFragment 中實現 OnSharedPreferenceChangeListener 但它似乎不起作用( onSharedPreferenceChanged
似乎從未被調用)。
到目前為止,這是我的代碼:
設置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();
}
}
設置片段.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, ""));
}
}
}
首選項.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>
此外,PreferenceFragment 甚至是監聽偏好更改的正確位置還是我應該在 Activity 中執行此操作?
我相信你只需要在你的PreferenceFragment
注冊/取消注冊Listener
,它就會工作。
@Override
public void onResume() {
super.onResume();
getPreferenceManager().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
}
@Override
public void onPause() {
getPreferenceManager().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
super.onPause();
}
根據您想要做什么,您可能不需要使用偵聽器。 對首選項的更改會自動提交給SharedPreferences
。
antew 的解決方案效果很好,在這里您可以看到 Android v11 以后的完整偏好活動:
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確的。 但我更喜歡這個替代方案,因為您立即擁有導致更改的 Preference 實例。
@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;
}
});
}
這從 PreferenceFragment.onCreate() 對我有用
OnSharedPreferenceChangeListener listener =
new SharedPreferences.OnSharedPreferenceChangeListener()
{
public void onSharedPreferenceChanged(SharedPreferences prefs, String key)
{
showDialog();
}
};
這是一種避免任何潛在內存泄漏的方法:
@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);
}
另一個完整的例子,讓你看到整個畫面。
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);
}
}
}
我最近完成組建自己PreferenceScreen
使用Preferences API
,所以我想我會貢獻我自己的完整的例子。這包括更新Summary
,以新的/改變的價值,以及聽力和反應的變化。
附注。 要回答你的最后一個問題:要顯示的默認值Summary
在初始創建的PreferenceScreen
(之前的值的任何變化),你可以簡單地設置android:summary
您選擇的值,從內部preferences.xml
直接文件 - 然后,一旦值發生更改,它將使用下面示例中包含的代碼自動更新。 就個人而言,我使用的簡短說明Preference
作為我的初步Summary
,我中設置preferences.xml
,然后一旦該值沒有得到改變,第一次,它只會顯示當前值作為Summary
從此..
無論如何,這是我的完整示例:
設置片段.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();
}
}
我希望這有幫助!
非常感謝任何積極的反饋,因為我對 StackOverflow 還很陌生;)
快樂編碼!
您只需要在onResume()
方法中取消指定的 Prefernce 類。 在我的情況下,我使用的是SwitchPreference
類,因此代碼類似於- 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
值的活動中,只需使用SharedPreference
對象來調用值並觸發它。
如果您只想更新摘要,使用androidx 首選項庫(請參閱官方指南),並在您的布局 xml 中添加以下屬性就足夠了:
<EditTextPreference
...
app:useSimpleSummaryProvider="true" />
使用 PreferenceFragmentCompat 在 Kotlin 上的解決方案
https://developer.android.com/reference/androidx/preference/PreferenceFragmentCompat
當 prefChange 時收聽
class SettingsFragment : PreferenceFragmentCompat() {
override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
setPreferencesFromResource(R.xml.root_preferences, rootKey)
val prefListener =
OnSharedPreferenceChangeListener { prefs, key ->
val valueChanged = preferenceManager.sharedPreferences.getString(key,key)
when(valueChanged){
getString(R.string.value_lang_en) -> applyLang(valueChanged)
getString(R.string.value_lang_th) -> applyLang(valueChanged)
}
}
preferenceManager.
sharedPreferences.
registerOnSharedPreferenceChangeListener(prefListener)
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.