Note: For better performance and tooling support, you should instead build your layout with ConstraintLayout.
All children of a
stacked one after the other, so a vertical list will only have one child per
row, no matter how wide they are, and a horizontal list will only be one row
high (the height of the tallest child, plus padding). A
LinearLayout respects margins between children
and the gravity (right, center, or left alignment) of each child.
LinearLayout also supports assigning a
weight to individual children with the
This attribute assigns an "importance" value to a view in
terms of how much space it should occupy on the screen. A larger weight value allows it to expand
to fill any remaining space in the parent view.
Child views can specify a weight value, and then any remaining space in the view group is
assigned to children in the proportion of their declared weight. Default
weight is zero.
To create a linear layout in which each child uses the same amount of
space on the screen, set the
android:layout_height of each view to
"0dp" (for a
vertical layout) or the
android:layout_width of each view to
"0dp" (for a
layout). Then set the
android:layout_weight of each view to
You can also create linear layouts where the child elements use different amounts of space on the screen:
- If there are three text fields and two of them declare a weight of 1, while the other is given no weight, the third text field without weight doesn't grow. Instead, this third text field occupies only the area required by its content. The other two text fields, on the other hand, expand equally to fill the space remaining after all three fields are measured.
- If there are three text fields and two of them declare a weight of 1, while the third field is then given a weight of 2 (instead of 0), then it's now declared more important than both the others, so it gets half the total remaining space, while the first two share the rest equally.
The following code snippet shows how layout weights might work in a "send message" activity. The To field, Subject line, and Send button each take up only the height they need. This configuration allows the message itself to take up the rest of the activity's height.
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="16dp" android:paddingRight="16dp" android:orientation="vertical" > <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="@string/to" /> <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="@string/subject" /> <EditText android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1" android:gravity="top" android:hint="@string/message" /> <Button android:layout_width="100dp" android:layout_height="wrap_content" android:layout_gravity="right" android:text="@string/send" /> </LinearLayout>