import java.util.ArrayList;import java.util.List; import android.app.Activity; public class ActivityManager {     public static List
    
      activities = new ArrayList
     
      ();     public static void addActivity(Activity activity) {        activities.add(activity);    }     public static void removeActivity(Activity activity) {        activities.remove(activity);    }     public static void finishAll() {        for (Activity activity : activities) {            if (!activity.isFinishing()) {                activity.finish();            }        }    }}