how to align text vertically center in android

I have arabic text, therefore I set gravity to right in order to start text from right side. Text starts from right now. But another issue is text starts to render from the top of the page. But I need to vertically center the text. Although I tried several variations I couldnt make it vertically center.

Here is the sample of my xml file.

<LinearLayout
            android:id="@+id/linearLayout5"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="right"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/textView2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_vertical"
                android:layout_marginBottom="23dp"
                android:gravity="right"
                android:padding="@dimen/padding_maintextview"
                android:text="@string/text"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:textSize="20sp" />
        </LinearLayout>

Problem is with above textview.

Here I have put whole xml file.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/page1background"
    android:paddingRight="@dimen/padding_large" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="196dp"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:gravity="center_horizontal"
        android:paddingTop="@dimen/padding_Title_Top"
        android:text="@string/text"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textSize="20sp" />

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/textView1"
        android:gravity="center_horizontal"
        android:orientation="vertical" >

        <View
            android:id="@+id/view1"
            android:layout_width="fill_parent"
            android:layout_height="5dp" />
    </LinearLayout>

    <ScrollView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/linearLayout2"
        android:layout_below="@id/linearLayout1"
        android:layout_gravity="center"
        android:padding="@dimen/padding_maintextview" >

        <LinearLayout
            android:id="@+id/linearLayout5"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="right"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/textView2"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_vertical"
                android:layout_marginBottom="23dp"
                android:gravity="right"
                android:padding="@dimen/padding_maintextview"
                android:text="@string/text"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:textSize="20sp" />
        </LinearLayout>
    </ScrollView>

    <LinearLayout
        android:id="@+id/linearLayout2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" >

        <View
            android:id="@+id/view2"
            android:layout_width="fill_parent"
            android:layout_height="100dp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" >

        <ImageButton
            android:id="@+id/back_arrow"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_marginBottom="30dp"
            android:layout_marginRight="45dp"
            android:layout_weight=".5"
            android:background="@drawable/backbut"
            android:contentDescription="@string/Description"
            android:onClick="onClickBtn"
            android:src="@drawable/backarrowpress" />

        <ImageButton
            android:id="@+id/copyButton"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_marginLeft="45dp"
            android:layout_weight=".5"
            android:background="@drawable/copy"
            android:contentDescription="@string/Description"
            android:onClick="onClickBtn" />
    </LinearLayout>

</RelativeLayout>

Can anybody show me where I have done the mistake? I think problem is clear. If not tell me in comments.

Herewith I have appended updated code after review your answers.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/page1background"
    android:paddingRight="@dimen/padding_large" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="196dp"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:gravity="center_horizontal"
        android:paddingTop="@dimen/padding_Title_Top"
        android:text="@string/text"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textSize="20sp" />

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/textView1"
        android:gravity="center_horizontal"
        android:orientation="vertical" >

        <View
            android:id="@+id/view1"
            android:layout_width="fill_parent"
            android:layout_height="5dp" />
    </LinearLayout>

    <ScrollView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_above="@id/linearLayout2"
        android:layout_below="@id/linearLayout1"
        android:layout_gravity="center"
        android:layout_centerInParent="true"
        android:padding="@dimen/padding_maintextview" >

        <LinearLayout
            android:id="@+id/linearLayout5"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="right"
            android:orientation="vertical" >

            <TextView
                android:id="@+id/textView2"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"
                android:layout_gravity="center_vertical"
                android:layout_marginBottom="23dp"
                android:gravity="center_vertical|right"
                android:padding="@dimen/padding_maintextview"
                android:text="@string/text"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:textSize="20sp" />
        </LinearLayout>
    </ScrollView>

    <LinearLayout
        android:id="@+id/linearLayout2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" >

        <View
            android:id="@+id/view2"
            android:layout_width="fill_parent"
            android:layout_height="100dp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" >

        <ImageButton
            android:id="@+id/back_arrow"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_marginBottom="30dp"
            android:layout_marginRight="45dp"
            android:layout_weight=".5"
            android:background="@drawable/backbut"
            android:contentDescription="@string/Description"
            android:onClick="onClickBtn"
            android:src="@drawable/backarrowpress" />

        <ImageButton
            android:id="@+id/copyButton"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_marginLeft="45dp"
            android:layout_weight=".5"
            android:background="@drawable/copy"
            android:contentDescription="@string/Description"
            android:onClick="onClickBtn" />
    </LinearLayout>

</RelativeLayout>

But I am in same situation. No text is vertically centered

Your TextView Attributes need to be something like,

<TextView ... 
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_vertical|right" ../>

Now, Description why these need to be done,

 android:layout_width="match_parent"
 android:layout_height="match_parent"

Makes your TextView to match_parent or fill_parent if You don't want to be it like, match_parent you have to give some specified values to layout_height so it get space for vertical center gravity. android:layout_width="match_parent" necessary because it align your TextView in Right side so you can recognize respect to Parent Layout of TextView.

Now, its about android:gravity which makes the content of Your TextView alignment. android:layout_gravity makes alignment of TextView respected to its Parent Layout.

Update:

As below comment says use fill_parent instead of match_parent. (Problem in some device.)

The problem is the padding of the font on the textview. Just add to your textview:

android:includeFontPadding="false"

just use like this to make anything to center

 android:layout_gravity="center"
 android:gravity="center"

updated :

android:layout_gravity="center|right"
android:gravity="center|right"

Updated : Just remove MarginBottom from your textview.. Do like this.. for your textView

<LinearLayout
        android:id="@+id/linearLayout5"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"  >

        <TextView
            android:id="@+id/textView2"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center" 
            android:gravity="center|right"
            android:text="hello" 
            android:textSize="20dp" />
    </LinearLayout>

Try to put android:gravity="center_vertical|right" inside parent LinearLayout else as you are inside RelativeLayout you can put android:layout_centerInParent="true" inside your scrollView.

In relative layout you need specify textview height:

android:layout_height="100dp"

Or specify lines attribute:

android:lines="3"