What Does Android:Layout_Weight Mean

What does android:layout_weight mean?

With layout_weight you can specify a size ratio between multiple views. E.g. you have a MapView and a table which should show some additional information to the map. The map should use 3/4 of the screen and table should use 1/4 of the screen. Then you will set the layout_weight of the map to 3 and the layout_weight of the table to 1.

To get it work you also have to set the height or width (depending on your orientation) to 0px.

android- meaning of layout_weight=0

For all the view which have layout_weight must have layout_height or layout_width as 0dp depending on the orientation and requirement of layout.

1. layout_weight="1" and layout_width="0dp" ==> that particular view will be stretched horizontally if there is not other layout adjacent to it.

2. layout_weight="0" and layout_width="100dp" ==> that particular layout will behave as it is there is no meaning of layout_weight in this scenario.

3. Best use of weight is when you need two views having same height/width that are adjacent to each other you can add width/height as "0dp" for both layout and weight as "1" for both the layout.

what is the difference between layout_weight and using dp?

This highly depends on the exact use case.

layout_weight depends on the number and size of the other views in the same ViewGroup.

dp (density-independant pixels) depends on the density of the device.

Usually, dp is used to have a view displayed at the same physical size on devices with different screen densities, while weight just makes sure that a view fills a certain percentage of its parent ViewGroup.

what is the difference between layout_weight and using dp?

This highly depends on the exact use case.

layout_weight depends on the number and size of the other views in the same ViewGroup.

dp (density-independant pixels) depends on the density of the device.

Usually, dp is used to have a view displayed at the same physical size on devices with different screen densities, while weight just makes sure that a view fills a certain percentage of its parent ViewGroup.

What is android:weightSum in android, and how does it work?

Per documentation, android:weightSum defines the maximum weight sum, and is calculated as the sum of the layout_weight of all the children if not specified explicitly.

Let's consider an example with a LinearLayout with horizontal orientation and 3 ImageViews inside it. Now we want these ImageViews always to take equal space. To acheive this, you can set the layout_weight of each ImageView to 1 and the weightSum will be calculated to be equal to 3 as shown in the comment.

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    <!-- android:weightSum="3" -->
    android:orientation="horizontal"
    android:layout_gravity="center">

   <ImageView
       android:layout_height="wrap_content"       
       android:layout_weight="1"
       android:layout_width="0dp"/>
  .....

weightSum is useful for having the layout rendered correctly for any device, which will not happen if you set width and height directly.

---

Related Topics