Android UI Tutorial - Android LinearLayout








Layout_weight and layout_gravity

In LinearLayout, you can apply the layout_weight and layout_gravity attributes to views contained within it: 

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical" >

    <Button
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:text="Button"
        android:layout_gravity="left"
        android:layout_weight="1" />

    <Button
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:text="Button"
              android:layout_gravity="center"
              android:layout_weight="2" />

    <Button
        android:layout_width="160dp"
        android:layout_height="wrap_content"
        android:text="Button"
        android:layout_gravity="right"
        android:layout_weight="3" />

</LinearLayout>
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Note

The layout_gravity attribute indicates the positions the views should gravitate towards.

The layout_weight attribute specifies the distribution of available space.

In the preceding example, the three buttons occupy about

  • 16.6% (1/(1+2+3) * 100),
  • 33.3% (2/(1+2+3) * 100), and
  • 50% (3/(1+2+3) *100)

of the available height, respectively.





Horizontal LinearLayout

If you change the orientation of the LinearLayout to horizontal, you need to change the width of each view to 0 dp. 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal" >

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

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

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