How to align LinearLayout at the center of its parent?

Please try this in your linear layout

android:layout_centerHorizontal="true"
android:layout_centerVertical="true"

These two attributes are commonly confused:

• android:gravity sets the gravity of the content of the View it's used on.
• android:layout_gravity sets the gravity of the View or Layout relative to its parent.

So either put android:gravity="center" on the parent or android:layout_gravity="center" on the LinearLayout itself.

I have caught myself a number of times mixing them up and wondering why things weren't centering properly...