thread random change image on imageview

I'm Beginner. I want change my image on imageview in Android and that images are periodically changed after some interval.

<LinearLayout android:id="@+id/la_01" android:layout_width="match_parent" android:layout_height="wrap_content" android:background="#eb68a3" android:orientation="vertical" >
<ImageView android:id="@+id/ig1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center|center" android:src="@drawable/a03" />
</LinearLayout>

public class MainActivity2 extends Activity { private ImageView ig1; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main_activity2);
int[] imageArray = new int[] { R.drawable.a01, R.drawable.a02, R.drawable.a04, R.drawable.a05, R.drawable.a06 }; ig1.setImageResource(R.drawable.a06);

How can I do ? please help me ,thanks