Page scroll when soft keyboard popped up

I have a <ScrollView> layout:

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/my_scrollview"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <EditText
            android:id="@+id/input_one"
            android:layout_width="300dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:inputType="number" >

         <EditText
            android:id="@+id/input_two"
            android:layout_width="300dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:inputType="number" >

         <EditText
            android:id="@+id/input_three"
            android:layout_width="300dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:inputType="number" >

          <Button
            android:id="@+id/ok_btn"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_marginTop="20dp"
            android:text="@string/ok_str" />

      </LinearLayout>
</ScrollView>

As you see above, the simple layout consists of three input fields and an "Ok" button.

I run my app with the above layout, when I tap on the 1st input field (@+id/input_one), the soft keyboard will pop up from the bottom of the screen, it hides the 3rd input field and the "Ok" button.

Since I use <ScrollView> , I thought I can scroll the page up in order to see the 3rd input field and "Ok"