Defaultvalues describes how to define the default values for preference in XML.
<checkboxpreference
android:key= "Default_toggle"
Android:defaultvalue= "true"
android:title= "@string/title_checkbox_preference"
android:summary= "@string/summary_checkbox_preference"/>
<edittextpreference
android:key= "Default_edittext"
Android:defaultvalue= "@string/default_value_edittext_preference"
android:title= "@string/title_edittext_preference"
android:summary= "@string/summary_edittext_preference"
android:dialogtitle= "@string/dialog_title_edittext_preference"/>
<listpreference
android:key= "Default_list"
Android:defaultvalue= "@string/default_value_list_preference"
android:title= "@string/title_list_preference"
android:summary= "@string/summary_list_preference"
android:entries= "@array/entries_list_preference"
android:entryvalues= "@array/entryvalues_list_preference"
android:dialogtitle= "@string/dialog_title_list_preference"/>