How to add a button to an preference activity

[aliov_85]

Hello,

I've an activity as follows:

public class NewPhysAct extends PreferenceActivity

I use preferences to display a form.

<PreferenceScreen
  xmlns:android="http://schemas.android.com/apk/res/android">
  <PreferenceCategory
      android:title="New phyisical activity">
  
<ListPreference 
    android:entryValues="@array/typofactvalues"
    android:entries="@array/typofact"
    android:key="typact"
    android:title="Activitytype"
    android:dialogTitle="Type of activity"
    android:defaultValue="0.9"></ListPreference>
</PreferenceCategory>
  <EditTextPreference
      android:key="duration"
      android:title="Duration"
      android:dialogTitle="Choose you activity"
      android:defaultValue="0"
      android:numeric="integer">
  </EditTextPreference>  
</PreferenceScreen>

How can I add a button like "ok" which I can use to change activity?

Thanks in advance