在Android中持久地以编程方式添加首选项

Question

basically what I want is this:

-> I have some settings that (of course) can be modified by the user, on of it is the 'number of cubes'
-> There is an other setting which depends on this setting (movement)
----> if there is one cube the setting is disabled (this works)
----> if there are two cubes there are two options for movement and the setting is enabled (this works too)
----> if there are four cubes there needs to be a choice added for movement and here lays my problem:

I can programmatically change the value of the ListPreference to add this setting but:
-> when the user sets the added value "paired"
and
-> (s)he moves away from the settings, the setting is read correctly
however
-> when the users moves back to the settings the setting is set to the first element of the list(synchronized), not being the choice (s)he made earlier
-> the setting (paired) is remembered by the SharedPreferences instance which I get by calling:

    PreferenceManager.getDefaultSharedPreferences(context);

but when moving to the settings again shows the wrong value for the setting (which nobody wants)

How do I persist a programmatically added value?

Of course the reason is that I read the preferences.xml again when the Activity is resumed, but I don't know how to persist the choice made by the user when the Activity is recreated.

This is my code: (the two methods that matter)

    public class SettingsActivity extends PreferenceActivity implements
    SharedPreferences.OnSharedPreferenceChangeListener {

@Override
public void onCreate(Bundle savedInstanceState) {
    Log.d("SA", "onCreate");

    super.onCreate(savedInstanceState);

    addPreferencesFromResource(R.xml.preferences);

    updateLists();
}

private void updateLists() {
    Log.d("SA", "updateLists");
    Preference numberOfCubesPref = findPreference("numberOfCubes");
    Preference tupleTypePref = findPreference("tuple");
    Preference movementTypePref = findPreference("movement_type");
    Preference pictureDistributionPref = findPreference("distribution_of_pictures");

    ListPreference numberOfCubesListPref = (ListPreference) numberOfCubesPref;

    if(numberOfCubesListPref.getEntry() == null){
        numberOfCubesListPref.setValueIndex(0); 
    }

    numberOfCubesPref.setSummary(numberOfCubesListPref.getEntry());

    ListPreference movementTypeListPref = (ListPreference) movementTypePref;

    if(movementTypeListPref.getEntry() == null){
        movementTypeListPref.setValueIndex(0); 
    }

    if (numberOfCubesListPref.getEntry().equals("Four")) {
        movementTypePref.setEnabled(true);
        pictureDistributionPref.setEnabled(true);

        CharSequence[] oldEntries = movementTypeListPref.getEntries();

        if (oldEntries.length == 2) {

            Log.d("SA","length is twoo");

            CharSequence[] newEntries = new CharSequence[oldEntries.length + 1];

            newEntries[0] = oldEntries[0];
            newEntries[1] = "Paired";
            newEntries[2] = oldEntries[1];

            movementTypeListPref.setEntries(newEntries);

            CharSequence[] oldEntryValues = movementTypeListPref
                    .getEntryValues();

            CharSequence[] newEntryValues = new CharSequence[oldEntryValues.length + 1];

            newEntryValues[0] = oldEntryValues[0];
            newEntryValues[1] = "Paired";
            newEntryValues[2] = oldEntryValues[1];

            movementTypeListPref.setEntryValues(newEntryValues);
        }

    } else if (numberOfCubesListPref.getEntry().equals("Two")) {
        movementTypePref.setEnabled(true);
        pictureDistributionPref.setEnabled(true);

        CharSequence[] oldEntries = movementTypeListPref.getEntries();

        if (oldEntries.length == 3) {

            CharSequence[] newEntries = new CharSequence[oldEntries.length - 1];

            newEntries[0] = oldEntries[0];
            newEntries[1] = oldEntries[2];

            movementTypeListPref.setEntries(newEntries);

            CharSequence[] oldEntryValues = movementTypeListPref
                    .getEntryValues();

            CharSequence[] newEntryValues = new CharSequence[oldEntryValues.length - 1];

            newEntryValues[0] = oldEntryValues[0];
            newEntryValues[1] = oldEntryValues[2];

            movementTypeListPref.setEntryValues(newEntryValues);
        }
    } else {
        movementTypePref.setEnabled(false);
        pictureDistributionPref.setEnabled(false);
    }

    ListPreference pictureDistributionListPref = (ListPreference) pictureDistributionPref;
    ListPreference tupleTypeListPref = (ListPreference) tupleTypePref;

    if(tupleTypeListPref.getEntry() == null){
        tupleTypeListPref.setValueIndex(0); 
    }

    CharSequence[] entries = pictureDistributionListPref.getEntries();

    CharSequence target, replacement;

    if (tupleTypeListPref.getEntry().equals("Two of the same kind")) {
        target = "Triplet";
        replacement = "Pair";
    } else {
        target = "Pair";
        replacement = "Triplet";
    }

    for (int i = 0; i < entries.length; i++) {
        entries[i] = ((String) entries[i]).replace(target, replacement);
    }

    pictureDistributionListPref.setEntries(entries);

    if(pictureDistributionListPref.getEntry() == null){
        pictureDistributionListPref.setValueIndex(0); 
    }

    tupleTypePref.setSummary(tupleTypeListPref.getEntry());
    movementTypePref.setSummary(movementTypeListPref.getEntry());
    pictureDistributionPref.setSummary(pictureDistributionListPref.getEntry());
}

and my preferences.xml (relevant piece):

        <ListPreference
    android:dialogTitle="@string/choose_movement_type"
    android:enabled="false"
    android:entries="@array/movement_type_entries"
    android:entryValues="@array/movement_type_values"
    android:key="movement_type"
    android:title="@string/movement_type" />

and strings.xml: (relevant piece)

        <string name="movement_type">Movement type</string>
<string name="choose_movement_type">How do you want to control the cubes?</string>

<string-array name="movement_type_entries">
    <item>Synchronized</item>
    <item>Independent</item>
</string-array>

<string-array name="movement_type_values">
    <item>Synchronized</item>
    <item>Independent</item>
</string-array>

The activity is called from within an other activity like this:

            settings.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent myIntent = new Intent(MainActivity.this,
                    SettingsActivity.class);
            MainActivity.this.startActivity(myIntent);
        }
    });

any help/comments/tips are welcome :)

S.

Answer 1

it looks like you are modifying the preference temporary. to save the prefrences and be sure it remains the same, use sharedPreferencesTurbo