Is it possible to evenly distribute buttons across the width of a LinearLayout

Expanding on fedj's answer, if you set layout_width to 0dp and set the layout_weight for each of the buttons to 1, the available width will be shared equally between the buttons.

If you don't want the buttons to scale, but adjust the spacing between the buttons (equal spacing between all buttons), you can use views with weight="1" which will fill the space between the buttons:

    <Space
        android:layout_width="0dp"
        android:layout_height="1dp"
        android:layout_weight="1" >
    </Space>

    <ImageButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:adjustViewBounds="true"
        android:background="@null"
        android:gravity="center_horizontal|center_vertical"
        android:src="@drawable/tars_active" />

    <Space
        android:layout_width="0dp"
        android:layout_height="1dp"
        android:layout_weight="1" >
    </Space>

    <ImageButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:adjustViewBounds="true"
        android:background="@null"
        android:gravity="center_horizontal|center_vertical"
        android:src="@drawable/videos_active" />

    <Space
        android:layout_width="0dp"
        android:layout_height="1dp"
        android:layout_weight="1" >
    </Space>

You can do this by giving both Views a layout_width of 0dp and a layout_weight of 1:

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

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

    <TextView
        android:layout_width="0dp"
        android:text="example text"
        android:layout_height="wrap_content"
        android:layout_weight="1"/>

</LinearLayout>

The way android layout_weight works is that:

• first, it looks to the size that a View would normally take and reserves this space.
• second, if the layout is match_parent then it will divide the space that is left in the ratio of the layout_weights. Thus if you gave the Views layout_weight="2" and layout_weight="1",the resultant ratio will be 2 to 1,that is : the first View will get 2/3 of the space that is left and the other view 1/3.

So that's why if you give layout_width a size of 0dp the first step has no added meaning since both Views are not assigned any space. Then only the second point decides the space each View gets, thus giving the Views the space you specified according to the ratio!

To explain why 0dp causes the space to devide equally by providing an example that shows the opposite: The code below would result in something different since example text now has a width that is greater than 0dp because it has wrap_content instead making the free space left to divide less than 100% because the text takes space. The result will be that they do get 50% of the free space left but the text already took some space so the TextView will have well over 50% of the total space.

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

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

    <TextView
        android:layout_width="wrap_content"
        android:text="example text"
        android:layout_height="wrap_content"
        android:layout_weight="1"/>

</LinearLayout>

You may use it with like the following.

<LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:layout_marginTop="15dp">
    <Space
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Save"/>
    <Space
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Reset"/>
    <Space
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="cancel"/>
    <Space
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"/>
</LinearLayout>