github: T06.08_PreferenceSummary

* Reference: Udacity Nanodegree Program- Become an Android Developer *

• Implement OnSharedPreferenceChangeListener.
• Create a setPreferenceSummary which takes a Preference and String value as parameters.
• In onCreatePreferences, get the preference screen, get the number of preferences and iterate through all of the preferences if it is not a checkbox preference, call the setSummary method passing in a preference and the value of the preference.
• Override onSharedPreferenceChanged and, if it is not a checkbox preference, call setPreferenceSummary on the changed preference.
• Register and unregister the OnSharedPreferenceChange listener, in onCreate and onDestroy respectively.

// TODO (1) Implement OnSharedPreferenceChangeListener
public class SettingsFragment extends PreferenceFragmentCompat implements OnSharedPreferenceChangeListener

TODO (2) Create a setPreferenceSummary.
This method should check if the preference is a ListPreference and, if so, find the label associated with the value. 

public void setPreferenceSummary(Preference preference, String value){
    if(preference instanceof ListPreference){
        ListPreference listPreference = (ListPreference)preference;
        int prefIndex = listPreference.findIndexOfValue(value);
        if(prefIndex >= 0){
            listPreference.setSummary(listPreference.getEntries()[prefIndex]);
        }
    }
}

// TODO (3) Get the preference screen, get the number of preferences and iterate through
// all of the preferences if it is not a checkbox preference, call the setSummary method
// passing in a preference and the value of the preference
SharedPreferences sharedPreferences = getPreferenceScreen().getSharedPreferences();
PreferenceScreen preferenceScreen = getPreferenceScreen();
int count = preferenceScreen.getPreferenceCount();

for(int i=0 ; i< count; i++){
    Preference preference = preferenceScreen.getPreference(i);
    if(!(preference instanceof CheckBoxPreference)){
        String value = sharedPreferences.getString(preference.getKey(),"");
        setPreferenceSummary(preference, value);
    }
}

// TODO (4) Override onSharedPreferenceChanged and, if it is not a checkbox preference,
// call setPreferenceSummary on the changed preference
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
    Preference preference = findPreference(key);

    if(preference != null){
        if(!(preference instanceof CheckBoxPreference)){
            String value = sharedPreferences.getString(preference.getKey(), "");
            setPreferenceSummary(preference, value);
        }
    }

}

// TODO (5) Register and unregister the OnSharedPreferenceChange listener (this class) in
// onCreate and onDestroy respectively.
public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
}

public void onDestroy(){
    super.onDestroy();
    getPreferenceScreen().getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
}