How to detect if changes were made in the preferences?
I have a class that extends PreferenceActivity and shows the preference screen of my app. Is it possible to check if any changes were made to the preferences?
This helps...
http://developer.android.com/reference/android/content/SharedPreferences.OnSharedPreferenceChangeListen开发者_如何学编程er.html
Other related post: SharedPreferences.onSharedPreferenceChangeListener not being called consistently
public class PreferenceClass extends PreferenceActivity {
OnSharedPreferenceChangeListener listener;
public void onCreate(Bundle savedInstanceState) {
SharedPreferences prefs = this.getSharedPreferences("settings", 0);
listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
public void onSharedPreferenceChanged(SharedPreferences prefs, String key) {
int flag = 1;
}
};
prefs.registerOnSharedPreferenceChangeListener(listener);
super.onCreate(null);
addPreferencesFromResource(R.xml.settings);
}
}
Do
SharedPreferences.OnSharedPreferenceChangeListener spChanged = new
SharedPreferences.OnSharedPreferenceChangeListener() {
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
String key) {
// your stuff here
}
};
In your PreferenceActivity
, ie make it a member of your PreferenceActivity
class and then do registerOnSharedPreferenceChangeListener(spChanged)
in the PreferenceActivity.onCreate()
method.
That's what I do and I never have a problem.
Else it's your conditional checking in the listener that is at fault. Post the code.
EDIT:
From the code you posted, you should make prefs
a class member variable so it has a global scope.
And do prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
instead of getSharedPreferences
because you haven't created that file.
To create a file you need to use PreferenceManager
. To get a PreferenceManager
, use Activity.getPreferenceManager()
.
In your PreferenceActivity
class, implement the SharedPreferences.OnSharedPreferenceChangeListener
interface. Add the required onSharedPreferenceChanged
method to your class and register it in the onCreate
.
See sample code here:
public class MyPreferences extends PreferenceActivity implements SharedPreferences.OnSharedPreferenceChangeListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.fw_preferences); //deprecated
PreferenceManager.getDefaultSharedPreferences(this).registerOnSharedPreferenceChangeListener(this);
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
// handle the preference change here
}
}
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