CardView has extra margin in each edge on Pre-Lollipop

Question

Here are two pictures.

on Lollipop:

on Pre-Lollipop:

Answer 1

If the Android 4 (pre-lollipop) behavior is desired, adding app:cardUseCompatPadding="true" to the CardView should fix it.

If the Android 5+ behavior is desired (which is actually the right behavior of card views according to material guidelines), the exact same thing can not be easily achieved. I usually use this fix to avoid defining multiple layout files and have reasonable output on all devices:

<android.support.v7.widget.CardView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:contentPaddingRight="@dimen/fix_cardview"
    app:contentPaddingLeft="@dimen/fix_cardview"
    app:contentPaddingTop="@dimen/fix_cardview_vertical"
    app:contentPaddingBottom="@dimen/fix_cardview_vertical" />

and in normal values/dimens.xml file we should have:

<dimen name="fix_cardview">-8dp</dimen>
<dimen name="fix_cardview_vertical">-12dp</dimen>

and in values-v21/dimens.xml:

<dimen name="fix_cardview">0dp</dimen>
<dimen name="fix_cardview_vertical">0dp</dimen>

note that the numbers -8dp and -12dp might have to be adjusted for your layout, since they depend on elevation, etc.

This is only a work-around to avoid ugly paddings in Android 4 views, without using different views in different layout files (which usually makes the code more difficult to maintain)