Enable and disable option in PreferenceActivity

Question

I am new to creating PreferenceActivity. My question is how to enable and disable option in preference screen by changing other preference?

My prefs.xml:

<ListPreference
    android:entries="@array/units"
    android:entryValues="@array/lunits"
    android:key="listUnits"
    android:summary="Units schosssing"
    android:title="Units" android:defaultValue="C"/>

 <ListPreference
    android:entries="@array/palette"
    android:entryValues="@array/lpalette"
    android:key="listpalette"
    android:summary="Palette schosssing"
    android:title="Palette" 
    android:defaultValue="1"/>

In the listUnits there are 2 options, Celsius and Fahrenheit, so if user selects Celsius the listpalette should get enabled, and if user selects Fahrenheit becomes disabled, how can I do this?

My settings activity:

public class SettingsActivity extends PreferenceActivity
{
    @Override
    protected void onCreate(final Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        getFragmentManager().beginTransaction().replace(android.R.id.content, new MyPreferenceFragment()).commit();             
    }

    public static class MyPreferenceFragment extends PreferenceFragment
    {
        @Override
        public void onCreate(final Bundle savedInstanceState)
        {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.prefs);
        }
    }

}

Answer 1

This code may be useful to you. Can take as reference.

First take instance of both of the ListPreference and apply this method.

ListPreference mlistUnits, mlistPalette;
mlistUnits= (ListPreference)findPreference("listUnits");
mlistPalette= (ListPreference)findPreference("listpalette");

mlistUnits.setEnable(false);
mlistPalette.setEnabled(true);

and use below listner

OnPreferenceChangeListener listener = new OnPreferenceChangeListener() {    
@Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
    // newValue is the value you choose
    return false;
}
};

apply listener to ListPreference

mlistPalette.setOnPreferenceChangeListener(listener);

Answer 2

Firstly you can set default value for your listUnits listpreference to celcius or Fahrenheit ,according this you can make enable-disable your second listpreference.

Now when changing your Preference by selecting anyone of them you can follow below procedure.

1) implement OnSharedPreferenceChangeListener in your MyPreferenceFragment class and override the method onSharedPreferenceChanged

2) Code like below in your method

  @Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences,
        String key) {
    // TODO Auto-generated method stub
    if (key.equals("listUnits")) {
                     final String value = sharedPreferences.getString(key, "");
                     Preference Pref_cec=findPreference("listpalette");
        if (value.equals("celcius")) {
                     wallpaperPref_admin.setEnabled(true);
                    }else{
                      wallpaperPref_admin.setEnabled(false);
                    }
             }
      }

Hope it will Help. Let me know if anything missing in my post.

Answer 3

As your second list is evaluated on basic of first list, what you may do

1. Look for preference click on the First list, get the value of preference clicked.

2. Using this value simply enable/disable your second list.