java - TextView not centering for large sets of text -

i have problem textviews. use code below center text both horizontally , vertically. if put text in, no longer stays centered. how can work around this?

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"      android:layout_width="fill_parent"     android:layout_height="fill_parent" >  <textview         android:id="@+xx/x"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_centerhorizontal="true"         android:layout_centervertical="true"         android:layout_margintop="22dp"         android:text="textview"         android:textsize="24dp" /> 

<textview     android:id="@+xx/x"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:gravity="center"     android:layout_centerhorizontal="true"     android:layout_margintop="22dp"     android:text="textview"     android:textsize="24sp" />