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Android LinearLayout, set background to Transparent

I am inflating a bottom_sheet_layout. It contains a LinearLayout as the root element. It has one child CardView.
I've tried the following:
setting `android:background` property to
1. #00FFFFFF
2. #00000000
3. #android:color/transparent
setting the background color of LinearLayout programatically
`LinearLayout l = container.findViewById(R.id.root_element);
l.setBackgroundColor(Color.TRANSPARENT);`
This is the BottomSheet.Class that is linked to the bottom_sheet_layout
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.bottom_sheet_layout, container, false);
LinearLayout l = container.findViewById(R.id.root_element);
l.setBackgroundColor(Color.TRANSPARENT);
return v;
}
This is the full bottom_sheet_layout
<?xml version="1.0" encoding="utf-8" ?>
<LinearLayout
android:id="#+id/root_element"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:layout_margin="16dp">
<!-- A CardView that contains a TextView -->
<androidx.cardview.widget.CardView
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="#+id/card_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="8dp"
card_view:cardCornerRadius="4dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/poiName"
android:fontFamily="#font/comfortaa_bold"
android:text="#string/poiName"
android:textSize="20sp"
android:layout_marginTop="20dp"
android:layout_marginLeft="20dp"
android:layout_marginBottom="20dp"/>
<!--Location-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginRight="20dp"
android:layout_marginBottom="10dp"
android:fontFamily="#font/work_sans_medium"
android:text="#string/ui_location"
android:textFontWeight="800" />
<TextView
android:id="#+id/location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginRight="20dp"
android:layout_marginBottom="10dp"
android:fontFamily="#font/work_sans"
android:text="#string/ui_location_addr" />
</LinearLayout>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
android:layout_marginTop="10dp"
android:layout_marginBottom="20dp"
android:layout_marginRight="20dp"
android:src="#drawable/share"
android:scaleType="center"
card_view:backgroundTint="#color/colorPrimary" />
</LinearLayout>
</androidx.cardview.widget.CardView>
</LinearLayout>
This is the Map Fragment. Here is where I inflate the bottom_sheet_layout
<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:map="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MapsActivity" />
Following several guides, I still could not get the #00FFFFFF method to work. Programmatically setting the color to transparent, crashes the application.
It seems that in earlier questions on StackOverflow, setting the background to the hex code with alpha value used to work. Now I only get a dim gray background.
Screenshots of the application
Image Layout
App ScreenShot

If you are not using MapView, I supposed that you are inflating the Google Map + bottom_sheet_layout in the same fragment. If Yes, I think that your issue is not the LinearLayout transparency but you are inserting bottom_sheet_layout to the bottom of the fragment container, not over the map.
You can use this layout for your Map fragment
(androidx, but very similar if you are using android)
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- use this fragment for your google map -->
<fragment
android:id="#+id/google_map"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
<!-- use this fragment for your bottom_sheet class -->
<fragment
android:id="#+id/bottom_sheet"
android:layout_margin="16dp" // with this you do not need the LinearLayout root_element
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
Then, you can play with your CardView (or LinearLayout) visibility to show the card or not.
Other layouts are possible like using directly the card view instead of a Fragment.

I think I can help you with some sort of solutions, which you can also try and see if that works or not.
Make use of alpha property in your .java file
Range the value as per your ease
LinearLayout l = container.findViewById(R.id.root_element);
l.setAlpha(0.4);
You can make use of alpha in your XML file too:
<LinearLayout
android:id="#+id/l1"
android:alpha="0.5"
android:layout_width="190dp"
android:layout_height="match_parent">
0.0 is for fully transparent and 1.0 is for fully opaque.
Let me know if any of the solutions work for you. However, do more research here, you will definitely get a solution. Happy coding.

Try background null.
<LinearLayout
android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:background="#null">
......
</LinearLayout>

Are you sure that the child layout elements doesn't have backgrounds?

Issue while setting Footer layout in ListView

Below is my Footer Layout for setting it for my ListView :
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/gray_cell_bg">
<TextView
android:text="footer"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
It's working fine. But, What if I want to set an emptyview with some background color in my ListView's footer ?
If I am doing it as below, ListView not showing footer view. :
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/gray_cell_bg">
</RelativeLayout>
I am setting footer as below :
View footerView = ((LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE)).inflate(R.layout.footer_for_gym_list, null);
listGymSuggestions.addFooterView(footerView);
Please guide me How can I set empty footer with some height and background color in ListView ?

The View is there but it has NO height so you must add your own height value may be 24dp or something and set it as a footer you can even add a width if you want. For instance here I am adding a height of 24dp:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="24dp"
android:background="#color/gray_cell_bg">
</RelativeLayout>

If there is no child in that layout, It will not be shown. If you have problem with setting specific height(when you are adding child dynamically), you can use padding like,
android:padding="20dp"

I added a button as a footer in one of my layout.
Here is my code. You may add anything you want.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<include
android:id="#+id/search_toolbar"
layout="#layout/search_toolbar" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal">
<ProgressBar
android:id="#+id/indeterminateBar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center" />
</LinearLayout>
<ListView
android:id="#+id/listView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_above="#+id/emp_button"
android:layout_below="#+id/search_toolbar" />
<TextView
android:id="#+id/tvsample"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/search_toolbar"
android:layout_marginTop="200dp"
android:gravity="center_horizontal"
android:textAppearance="#style/TextAppearance.AppCompat.Medium" />
<android.support.v7.widget.AppCompatImageButton
android:id="#+id/emp_button"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_alignParentBottom="true"
android:background="#color/Red"
android:src="#drawable/ic_add_employee"
android:text="#string/emp_button"
android:textSize="14sp" />

Issue is solved by adding an ImageView in Footer view as below :
footer.xml :
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/gray_cell_bg">
<ImageView
android:layout_width="match_parent"
android:layout_height="#dimen/com_facebook_profilepictureview_preset_size_normal"
android:scaleType="fitXY"
android:src="#color/gray_cell_bg" />
</RelativeLayout>

Android listview to overlay another view

I have a view which contains a top view (it's a mapview but it's not implemented yet) and a listview below it.
What I'm trying to do is to make the top of listview to be overlay the bottom of the top view a little bit. Here is something similar to what I'm trying to achieve :
(without the tab headers and the image will be the mapview)
I'm not sure how I can achieve that, here is what I have so far:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<View
android:id="#+id/map"
android:layout_width="match_parent"
android:layout_height="250dp"
android:background="#android:color/holo_red_dark">
</View>
<com.hmm.widgets.CustomListView
android:id="#+id/runners_list"
android:background="#android:color/darker_gray"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:dividerHeight="10dp"
android:divider="#android:color/darker_gray">
</com.hmm.widgets.CustomListView>
</RelativeLayout>
I've tried negative margin which didn't work. I'm not sure how can I achieve something similar. Should I be using FrameLayout?

You can use LinearLayout in your case and design the layout like this. This is a trick of setting a negative layout_marginTop to your custom ListView
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:orientation="vertical"
android:layout_height="match_parent">
<View
android:id="#+id/map"
android:layout_width="match_parent"
android:layout_height="250dp"
android:background="#android:color/holo_red_dark">
</View>
<com.hmm.widgets.CustomListView
android:id="#+id/runners_list"
android:background="#android:color/darker_gray"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="#dimen/activity_vertical_margin"
android:layout_marginRight="#dimen/activity_vertical_margin"
android:dividerHeight="10dp"
android:layout_marginTop="-40dp"
android:divider="#android:color/darker_gray">
</com.hmm.widgets.CustomListView>
</LinearLayout>

Complementing Reaz's answer, you can do it with RelativeLayout too without using negative margins (which are a bit controversial).
Note the last four attributes in the CustomListView: you constraint the height with alignParent*, set a dummy height which will be discarded, and offset the view from the top with a margin. The "negative offset" will be 250dp - 200dp = 50 dp.
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<View
android:id="#+id/map"
android:layout_width="match_parent"
android:layout_height="250dp"
android:background="#android:color/holo_red_dark">
</View>
<com.hmm.widgets.CustomListView
android:id="#+id/runners_list"
android:background="#android:color/darker_gray"
android:layout_width="match_parent"
android:dividerHeight="10dp"
android:divider="#android:color/darker_gray"
android:layout_height="0dp"
android:layout_marginTop="200dp"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true">
</com.hmm.widgets.CustomListView>
</RelativeLayout>

RecyclerView takes up all screenspace

So I'm having some trouble with a RecyclerView in a layout file
Here it is:
<android.support.v7.widget.RecyclerView
android:id="#+id/chat_listview"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingRight="#dimen/abc_action_bar_default_padding_material"
android:paddingLeft="#dimen/abc_action_bar_default_padding_material"
/>
<LinearLayout
android:layout_below="#id/chat_listview"
android:layout_width="match_parent"
android:layout_height="#dimen/bottom_bar_height"
android:orientation="horizontal"
>
<EditText
android:id="#+id/chat_input_edittext"
android:layout_weight="7"
android:layout_width="0dp"
android:layout_height="match_parent"
android:inputType="textAutoCorrect"
/>
<Button
android:id="#+id/chat_send_button"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent"
android:background="#drawable/ic_action_send_now"
/>
</LinearLayout>
The RecyclerView is visible and scrollable but the LinearLayout and the Views inside are not visible... I tried quite a few things but nothing has worked so far.
Can any of you please point me into the right direction?
Many thanks in advance!

When RecyclerView is drawn, it calculates all the remaining size on screen to itself before drawing the next elements and don't recalculate after the other elements are drawn, leaving them outside the screen.
The trick is to draw all other elements first, and leave RecyclerView for last. FrameLayout does not work anymore so use a relative layout and put the RecyclerView last on the XML layout file.
Example to add a bar with buttons below the RecyclerView:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16dp"
tools:context=".MainActivity"
>
<LinearLayout
android:id="#+id/pagination_btns"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_alignParentBottom="true"> //HERE YOU ALIGN THIS ELEMENT TO THE BOTTOM OF THE PARENT
<Button
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="#string/previous_btn_label"/>
<Space
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"/>
<Button
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="#string/next_btn_label"/>
</LinearLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/items_recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical"
android:layout_above="#id/pagination_btns"/> //HERE YOU ALIGN THE RECYCLERVIEW ABOVE THE PAGINATION BAR
</RelativeLayout>

Change the root view to a FrameLayout. Set the gravity of the LinearLayout to bottom
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="#+id/chat_listview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingRight="#dimen/abc_action_bar_default_padding_material"
android:paddingLeft="#dimen/abc_action_bar_default_padding_material"
/>
<LinearLayout
android:layout_below="#id/chat_listview"
android:layout_width="match_parent"
android:layout_height="#dimen/bottom_bar_height"
android:layout_gravity="bottom"
android:orientation="horizontal">
<EditText
android:id="#+id/chat_input_edittext"
android:layout_weight="7"
android:layout_width="0dp"
android:layout_height="match_parent"
android:inputType="textAutoCorrect"/>
<Button
android:id="#+id/chat_send_button"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent"
android:background="#drawable/ic_action_send_now"/>
</LinearLayout>
</FrameLayout>
Alternatively, you can wrap the linear layout in a FrameLayout
and set it to align_parentBottom = true if it is a relative layout or a linear layout at your root and you have other things in your view.

Android App Layout

I'm developing an android app for 2.2 ver.
My app must hav such structure:
[ Spinner here (fixed height) ]
[ ListView (not-fixed height) ]
[ ImageView (fixed-height) ]
I have to use only portrait orientation.
I use linearLayout for it. How can I calculate listView height to show spinner on the top of the screen, imageview on the bottom, and listview cover all free space, but not push others away from field of view.
It will be cool to make it dinamic for lots of screen resolutions.
Thank you

Use a relative layout to accomplish what you need.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<Spinner
android:id="#+id/spinner1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true" />
<ImageView
android:id="#+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:src="#drawable/icon" />
<ListView
android:id="#+id/listView1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#+id/spinner1"
android:layout_above="#+id/imageView1" />
</RelativeLayout>
By doing this listview will adjust its size so that it fits between the spinner and imageview on your screen

You need to use the android:layout_weight attribute on the variable-height item, so it fills the available space.
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Spinner
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<ListView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
/>
<ImageView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

Here is another way to do this, using weights. This may be the easiest approach.
You can put in to the weight a percentage of the screen you would like it to take up.
<?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" >
<Spinner
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="10"/>
<ListView
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="80"></ListView>
<ImageView
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="10"/>
</LinearLayout>
EDIT:
Now that i think about it, this will "fix" the size of all the widgets. They will be "fixed" at percentages of the screen. This will scale well with other screen sizes, but you did say you wanted ListView to not be fixed.