If you are using a string resource xml file (supports HTML tags), it can be done using<b> </b>
, <i> </i>
and <u> </u>
.
<resources>
<string name="your_string_here">
This is an <u>underline</u>.
</string>
</resources>
If you want to underline something from code use:
TextView tv = (TextView) view.findViewById(R.id.tv);
SpannableString content = new SpannableString("Content");
content.setSpan(new UnderlineSpan(), 0, content.length(), 0);
tv.setText(content);
Hope this helps