How to remove padding around buttons in Android?

Question

In my Android app, I have this layout:

<?xml version="1.0" encoding="utf-8" ?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
      android:layout_width="match_parent" 
      android:layout_height="match_parent" 
      android:orientation="vertical">

    <fragment
         android:id="@+id/map"
         android:layout_width="match_parent"
         android:layout_height="0dp" 
         android:layout_weight="1" 
         class="com.google.android.gms.maps.SupportMapFragment"/>

    <Button
        android:id="@+id/button_back"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="CloseActivity"
        android:padding="0dp"
        android:text="@+string/back" />

</LinearLayout>

In the preview and on the phone, it looks like:

As you can see on the button in the bottom area, there is some padding there.

How can I get rid of that, and let the button fully fill the bottom area?

Answer 1

For me the problem turned out to be minHeight and minWidth on some of the Android themes.

On the Button element, add:

<Button android:minHeight="0dp" android:minWidth="0dp" ...

Or in your button's style:

<item name="android:minHeight">0dp</item>
<item name="android:minWidth">0dp</item>