Set width of parent linear layout as percentage of the screen

Question

I am building an android application and I have a dialog fragment. The dialog fragment has a set width. However, the issue is that when the app is run on a device with a different screen size, the dialog fragment isn't centered properly.

Initially, what I had was:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="500dp"
  android:layout_height="wrap_content">

  <-- code goes here -->

</RelativeLayout>

As you can see, I have a relativeLayout with a defined width. Since I know that you can't use layout_weight in a relative layout, what I did was I wrapped that parent relative layout in a linear layout as such:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_weight="0.8"
    android:weightSum="1">

    <RelativeLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">

    </RelativeLayout>
</LinearLayout>

However, that doesn't work since the dialog fragment is cut when I run the application on a device with smaller screen size.

How can I set the width a dialog fragment as a percentage of the screen size? Is this possible at all or would I have to resort to setting it programmatically?

Answer 1

This is a correct way, if you want RelativeLayout have 40% width of the screen, but this technique cant apply to the parent layout, because parent layout doesn't have parent layout and android:layout_weight doesn't affect

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="100">

<RelativeLayout
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_weight="40">

</RelativeLayout>

Since I know that you can't use layout_weight in a relative layout

We can use layout_weight in any view and layout, if it direct child of a LinearLayout