How can my screen size increase in Android

Question

I got a screen with several input boxes and at end of it a button, but the button doesn't fit on the screen, as you can see on the image:

How can I get the button under the comment textbox. So when the multiline textbox expands, the button moves down?

EDIT: Here is my xml layout

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:fillViewport="true">

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="be.example.timelogger.NewLogActivity" >

    <TextView
        android:id="@+id/tvDate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="25dp"
        android:text="@string/dateText"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <TextView
        android:id="@+id/tvStartTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tvDate"
        android:layout_below="@+id/inputDate"
        android:layout_marginTop="22dp"
        android:text="@string/startTimeText"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <TextView
        android:id="@+id/tvEndTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tvStartTime"
        android:layout_below="@+id/inputStartTime"
        android:layout_marginTop="26dp"
        android:text="@string/endTimeText"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <TextView
        android:id="@+id/tvDurationTime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/inputEndTime"
        android:layout_centerVertical="true"
        android:text="@string/durationTimeText"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <EditText
        android:id="@+id/inputDate"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/tvDate"
        android:layout_marginLeft="18dp"
        android:layout_toRightOf="@+id/tvDuration"
        android:ems="10"
        android:inputType="date"
        android:onClick="showDatePickerDialog" >

        <requestFocus />
    </EditText>

    <EditText
        android:id="@+id/inputEndTime"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/tvEndTime"
        android:layout_alignBottom="@+id/tvEndTime"
        android:layout_alignLeft="@+id/inputDate"
        android:ems="10"
        android:inputType="time"
        android:onClick="showTimePickerDialogEnd" />

    <EditText
        android:id="@+id/inputStartTime"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/inputEndTime"
        android:layout_alignTop="@+id/tvStartTime"
        android:ems="10"
        android:inputType="time"
        android:onClick="showTimePickerDialogStart" />

    <TextView
        android:id="@+id/tvDuration"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tvEndTime"
        android:layout_centerVertical="true"
        android:text="@string/durationText"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <TextView
        android:id="@+id/tvCourse"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tvDuration"
        android:layout_below="@+id/tvDuration"
        android:layout_marginTop="30dp"
        android:text="@string/tvCourseText"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Spinner
        android:id="@+id/spinCourse"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/tvCourse"
        android:layout_toRightOf="@+id/tvDurationTime" />

    <EditText
        android:id="@+id/txtComment"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tvComment"
        android:layout_alignRight="@+id/inputEndTime"
        android:layout_below="@+id/tvComment"
        android:layout_marginTop="17dp"
        android:ems="10"
        android:isScrollContainer="true"
        android:inputType="textMultiLine"  />

    <TextView
        android:id="@+id/tvComment"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/tvCourse"
        android:layout_below="@+id/spinCourse"
        android:layout_marginTop="28dp"
        android:text="@string/commentText"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Button
        android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="@string/btnSaveText" />
</RelativeLayout>

Answer 1

Use a ScrollView so if there are more contents you can scorll. and off course different screen sizes will be handled too. Example:

<ScrollView>   
    <RelativeLayout> 
           your views here
    </RelativeLayout> 

</ScrollView>

In your code, the problem is that you align the button to parent bottom. Do this instead:

<Button
    android:id="@+id/btnSave"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"

    android:layout_below="@+id/tvComment"

    android:layout_centerHorizontal="true"
    android:text="@string/btnSaveText" />

This puts your button below the TextView and you might even don't need the ScrollView.