RelativeLayout: align View centered horizontal or vertical relative to other view

I have a much better solution than the accepted one. NO EXTRA NESTING! You can do this by combining two attributes on the smaller view. if you are centering horizontally you can use both align_start & align_end to the bigger view. Make sure the text gravity is centered btw "android:gravity="center". For Vertical alignment use both align_top & align_bottom. below is the modified implementation of your layout.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="43dp" >

<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignStart="@+id/second"
    android:layout_alignEnd="@+id/second"
    android:gravity="center"
    android:text="dynamic text" />

<TextView
    android:id="@+id/second"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@id/textView"
    android:gravity="center"
    android:text="centered below text 1" />

</RelativeLayout>

No need for unnecessary nesting like the accepted answer.

Use a separate parent layout for those views and add it in your main layout(can contain other things if you have)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    <LinearLayout
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:orientation="vertical"
         android:gravity="center"
         android:layout_marginLeft = "30dp">
        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="dynamic text" />

        <TextView
            android:id="@+id/second"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="centered below text 1" />
    </LinearLayout>
...
...
other veiws go here
...

</RelativeLayout>

Use the followings which suits you

    android:layout_centerHorizontal="true"
    android:layout_centerInParent="true"    
    android:layout_centerVertical="true"