Android TimeZone preference using 100% native resources, with no need to read timezones from external files. Automatically sorted and translated.

TimeZonePreference.java

package <your_package>;

import android.content.Context;
import android.util.AttributeSet;

/* You can use default ListPreference if you prefer.
   Got this lib from <link>https://github.com/afollestad/material-dialogs</link>
*/
import com.afollestad.materialdialogs.prefs.MaterialListPreference;

import java.util.HashMap;
import java.util.Map;
import java.util.TimeZone;
import java.util.TreeMap;

public class TimeZonePreference extends MaterialListPreference {

    public TimeZonePreference(Context context) {
        super(context);
        this.init();
    }

    public TimeZonePreference(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.init();
    }

    private void init() {
        String[] timezones = TimeZone.getAvailableIDs();

        Map<String, String> unsortedTimezonesMap = new HashMap<>();

        for (String timezoneId : timezones) {
            String timezoneName = TimeZone.getTimeZone(timezoneId).getDisplayName();

            if (timezoneId.trim().length() > 0 && unsortedTimezonesMap.get(timezoneName) == null) {
                unsortedTimezonesMap.put(timezoneId, timezoneName);
            }
        }

        Map<String, String> sortedTimezonesMap = new TreeMap<>(unsortedTimezonesMap);

        String[] countriesCodesArray = new String[unsortedTimezonesMap.size()];
        String[] countriesNamesArray = new String[unsortedTimezonesMap.size()];

        this.setEntryValues(sortedTimezonesMap.values().toArray(countriesCodesArray));
        this.setEntries(sortedTimezonesMap.keySet().toArray(countriesNamesArray));
    }
}


/* To use on your pref.xml */
/***************************************************
<<your_package>.TimeZonePreference
            android:defaultValue=""
            android:key="user_timezone"
            android:negativeButtonText="@null"
            android:positiveButtonText="@null"
            android:summary=""
            android:title="@string/pref_timezone"/>
/**************************************************/


/* Here's an util method to get a TimeZone name to set on your PreferencesFragment */

/****************************************
private String getTimeZoneNameByCode() {
  String currentPreferenceValue = userSharedPreferences.getString(Constants.PREFS_USER_TIMEZONE, Constants
      .EMPTY);
  String timeZoneCode = currentPreferenceValue.equals(Constants.EMPTY) ? TimeZone.getDefault().getID() :
      currentPreferenceValue;
  TimeZone tz = TimeZone.getTimeZone(timeZoneCode);
  return tz.getDisplayName();
}
****************************************/