If you need to specify different font sizes for text in a TextView from XML, you can assign this line:
<string name="hello"><big><big>Hello Big Text!</big></big>\n<small>Hello small text</small></string>
and use this line in TextView. Note that the new line is < \n 'instead of <br/>
<TextView android:id="@+id/text" android:layout_width="fill_parent" android:layout_height="match_parent" android:text="@string/hello" />
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