Set "gravity" attribute to a RelativeLayout not working

 How 

gravity

 affects
the subviews is shown in the image below.



I resized the widths of all the subviews
so that what is happening is more clear. 

Note that
the way 

RelativeLayout

 handles
gravity is to take all the subviews as a group and move them around the layout. This means that whichever
view is widest will determine how everything else is positioned. So gravity in a Relative layout is probably only useful if all the subviews have the same width.

Linear Layout with 

gravity

When you add 

gravity

 to
a 

LinearLayout

,
it does arrange the subviews as one would expect. 

For example, one could "save code" by setting the 

gravity

 of 

LinearLayout

 to 

center_horizontally

.
That way there is no need individually set the 

layout_gravity

 of
each subview. See the various options in the image below.





Note that when a view uses 

layout_gravity

,
it overrides the LinearLayout's gravity. (This can be seen in the title for the two layouts in the left image. The LinearLayout 

gravity

 was
set to 

left

and 

right

,
but the title TextView's 

layout_gravity

 was
set to 

center_horizontally

.)

Final notes

When positioning views within a RelativeLayout,
the general way to do it is adding things like the following to each view:

layout_alignParentTop

layout_centerVertical

layout_below

layout_toRightOf

If one wants to set all the views at once, a 

LinearLayout

 would
likely be better (or perhaps using a Style).

So to sum up,
The 

layout_gravity

 does
not work for subviews in a RelativeLayout.
The 

gravity

 of
a RelativeLayout does work, but not as one might expect.

From: http://stackoverflow.com/questions/42142058/why-doesnt-gravity-work-when-applied-to-relative-layout/42153928#42153928