How to remove default layout's padding/margin

Question

I have the following layout files:

activity_main.xml

Answer 1

Go into this file res/values/dimens.xml and change the values to 0dp just like in the code below.

<dimen name="activity_horizontal_margin">0dp</dimen>
<dimen name="activity_vertical_margin">0dp</dimen>

Answer 2

I know this is already answered question but, i just come across such an issue, the answer helped but not completely, as there was a right padding. I found out that, it is because of the padding set in the Theme i used. It might be helpful for those still see the padding. All you need to do is remove it.