Linear Layout and weight in Android


Question

I always read about this funny weight value in the Android documentations. Now I want to try it for the first time but it isn't working at all.

As I understand it from the documentations this layout:

  <LinearLayout
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:orientation="horizontal">

     <Button
        android:text="Register"
        android:id="@+id/register"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dip"
        weight="1" />

     <Button
        android:text="Not this time"
        android:id="@+id/cancel"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dip"
        weight="1" />

  </LinearLayout>

should create two buttons that are horizontally aligned and share the space equally. The problem is the two buttons don't grow to fill the space.

I would like the buttons to grow and fill the whole line. If both buttons are set to match parent only the first button is shown and fills the whole line.

1
248
5/14/2019 3:31:36 PM

Accepted Answer

You are not setting the layout_weight property. Your code reads weight="1" and it should read android:layout_weight="1".

150
9/13/2017 4:14:02 PM

3 things to remember:

  • set the android:layout_width of the children to "0dp"
  • set the android:weightSum of the parent (edit: as Jason Moore noticed, this attribute is optional, because by default it is set to the children's layout_weight sum)
  • set the android:layout_weight of each child proportionally (e.g. weightSum="5", three children: layout_weight="1", layout_weight="3", layout_weight="1")

Example:

    <LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:weightSum="5">

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

    <Button
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="3"
        android:text="2" />

    <Button
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="3" />

    </LinearLayout>

And the result:

Layout weight example


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