I've had severe trouble getting LayoutInflater to work as expected, and so did other people: How to use layoutinflator to add views at runtime?.
Why does LayoutInflater ignore the layout parameters I've specified? E.g. why are the layout_width
and layout_height
values from my resources XML not honored?
I've investigated this issue, referring to the LayoutInflater docs and setting up a small sample demonstration project. The following tutorials shows how to dynamically populate a layout using
LayoutInflater
.Before we get started see what
LayoutInflater.inflate()
parameters look like:R.layout.main_page
)attachToRoot
istrue
), or else simply an object that provides a set ofLayoutParams
values for root of the returned hierarchy (ifattachToRoot
isfalse
.)attachToRoot: Whether the inflated hierarchy should be attached to the root parameter? If false, root is only used to create the correct subclass of
LayoutParams
for the root view in the XML.Returns: The root View of the inflated hierarchy. If root was supplied and
attachToRoot
istrue
, this is root; otherwise it is the root of the inflated XML file.Now for the sample layout and code.
Main layout (
main.xml
):Added into this container is a separate TextView, visible as small red square if layout parameters are successfully applied from XML (
red.xml
):Now
LayoutInflater
is used with several variations of call parametersThe actual results of the parameter variations are documented in the code.
SYNOPSIS: Calling
LayoutInflater
without specifying root leads to inflate call ignoring the layout parameters from the XML. Calling inflate with root not equalnull
andattachRoot=true
does load the layout parameters, but returns the root object again, which prevents further layout changes to the loaded object (unless you can find it usingfindViewById()
). The calling convention you most likely would like to use is therefore this one:To help with layout issues, the Layout Inspector is highly recommended.
wanna add to main answer above
I tried to follow it but my recyclerView began to stretch every item to a screen
I had to add next line after inflating for reach to goal
I already added these params by xml but it didnot work correctly
and with this line all is ok
andig is correct that a common reason for LayoutInflater ignoring your layout_params would be because a root was not specified. Many people think you can pass in null for root. This is acceptable for a few scenarios such as a dialog, where you don't have access to root at the time of creation. A good rule to follow, however, is that if you have root, give it to LayoutInflater.
I wrote an in-depth blog post about this that you can check out here:
https://www.bignerdranch.com/blog/understanding-androids-layoutinflater-inflate/