Question

I am trying to programmatically delete one of the options in a list view from SharedPreferences. I have included simplified code below.

I have read through a ton of similar questions but it just will not seem to work for me. I must be misunderstanding a key concept. Please help.

I have tried using clear() and apply(). I have also tried adding an a line instead of deleting all without success.

I think I may be misunderstanding the concept of which keys to use and have tried alternates, but nothing seems to work.

my preferences.java

package il.preferences;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceActivity;

public class Preferences extends PreferenceActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        addPreferencesFromResource(R.xml.preferences);
        SharedPreferences preferences = getSharedPreferences(
                "myKey", MODE_PRIVATE);
        preferences.edit().remove("1").commit();
    }
}

my preference.xml

 <?xml version="1.0" encoding="utf-8" standalone="no"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >

    <PreferenceCategory android:title="Cat X" >
        <ListPreference
            android:defaultValue="1"
            android:entries="@array/myOptions"
            android:entryValues="@array/myValues"
            android:key="myKey"
            android:summary="Select an item"
            android:title="Choose" />
    </PreferenceCategory>

</PreferenceScreen>

my strings.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<resources>
    <string-array name="myOptions">
        <item>A</item>
        <item>B</item>
        <item>C</item>
    </string-array>
    <string-array name="myValues">
        <item>1</item>
        <item>2</item>
        <item>3</item>
    </string-array>
</resources>

Answer 1

My problem was that I conceptualised the preference framework wrong. I will share my wrong turns to help any other lost newbies.

I had confused the PreferenceScreen which I defined in my preferences.xml above and the file where the preferences are stored which can be seen on the DDMS perspective my.package.name_preferences.xml – use file manager – data – data – project name – shared_prefs to find and pull this file

<?xml version='1.0' encoding='utf-8' standalone='yes' ?>
<map>
<string name="myKey">1</string>
</map>

I then incorrectly proceeded to try use the preference editor to alter the PreferenceScreen

SharedPreferences preferences = getSharedPreferences("myKey", MODE_PRIVATE);
preferences.edit().remove("1").commit();

Eventually I found the sample code in the Google APIs
com.example.android.apis.ApiDemos
com/example/android/apis/preference
which have all the permutations I needed, in order to finally understand.

my eventual solution was to use a combination of
setPreferenceScreen(createPreferenceHierarchy());
addPreferencesFromResource(R.xml.preferences);

to incorporate both my static and dynamic preferences. The code for my dynamic preferences I add below although, (thanks to Google). I recommend looking at the google api rather than trying to find tutorials online or using books.

import java.util.List;
import android.os.Bundle;
import android.preference.ListPreference;
import android.preference.PreferenceActivity;
import android.preference.PreferenceCategory;
import android.preference.PreferenceScreen;

public class SetPreferenceActivityGB extends PreferenceActivity {
    private static final String LENGTH_DEFAULT = "4";
    private static final String LEVEL_DEFAULT = "level1";

    @SuppressWarnings("deprecation")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setPreferenceScreen(createPreferenceHierarchy());
        addPreferencesFromResource(R.xml.preferences);
    }


    private PreferenceScreen createPreferenceHierarchy() {
        PreferenceScreen root = getPreferenceManager().createPreferenceScreen(
                this);


        // Dialog based preferences
        PreferenceCategory dialogBasedPrefCat = new PreferenceCategory(this);
        root.addPreference(dialogBasedPrefCat);

        // List preference
        ListPreference listPref = new ListPreference(this);

// This is where I get my dynamic list of levels and use it as a character sequence to
// To make my list view dynamic.     
        List<String> myList ; 

        myList = Playsound.getAvailableLevels(); // Function which is Dynamic
        CharSequence[] cs = myList.toArray(new CharSequence[al.size()]);

        listPref.setEntries(cs);
        listPref.setEntryValues(cs);
        // listPref.setEntries(R.array.levels);
        // listPref.setEntryValues(R.array.levelsValues);
        listPref.setDialogTitle(R.string.level_title);
        listPref.setKey("level");
        listPref.setTitle(R.string.level_title);
        listPref.setValueIndex(0);
        listPref.setDefaultValue(LEVEL_DEFAULT);
        listPref.setSummary(R.string.level_summary);
        dialogBasedPrefCat.addPreference(listPref);

    }
}