defaultValue returned as empty string for Custom Preference class used in Preference XML

Question

I am trying to create a time selection preference by extending the DialogPreference. I have specified a android:defaultValue in the Preference XML. Everything works well, but when I try to read the value of the preference from code, I get an empty string. Ideally, if the preference is not set, I should get the value as 5:00 which is mentioned asandroid:defaultValue in the Preference XML.

When I retrieve the preference, how can I get the value specified as android:defaultValue in the Preference XML, if user has not yet set the preference?

<com.sample.package.TimeDialogPreference
        android:defaultValue="5:00"
        android:key="@string/pref_key_time"
        android:title="@string/pref_title_time"
        android:summary="@string/pref_summary_time"
        android:dialogLayout="@layout/preference_time"
    />