Why does the LinearLayout attribute “layout_weight” seem to do the opposite of what I think it should do?

Question

I\'m following this tutorial to learn about linear layouts. Here\'s the main layout file:

Answer 1

layout_weight is normally used with layout_width or layout_height set to wrap_content. Try it, you'll see that it then increases the layout sized based on which view has the higher weight.

Example

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

  <LinearLayout
      android:orientation="horizontal"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_weight="2">
      <TextView
          android:text="red"
          android:gravity="center_horizontal"
          android:background="#aa0000"
          android:layout_width="wrap_content"
          android:layout_height="fill_parent"
          android:layout_weight="1"/>

  </LinearLayout>

  <LinearLayout
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1">
    <TextView
        android:text="row one"
        android:textSize="15pt"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_weight="1"/>

  </LinearLayout>

</LinearLayout>

Answer 2

Emphasis on any remaining space...

I think it is a conflict between using fill_parent for height and the layout weight. Try setting android:layout_height="0dp" for both LinearLayouts.

Answer 3

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" android:weightSum="3">

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="2"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:background="#aa0000"
            android:gravity="center_horizontal"
            android:text="red" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:background="#00aa00"
            android:gravity="center_horizontal"
            android:text="green" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:background="#0000aa"
            android:gravity="center_horizontal"
            android:text="blue" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="fill_parent"
            android:layout_weight="1"
            android:background="#aaaa00"
            android:gravity="center_horizontal"
            android:text="yellow" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:orientation="vertical" >

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="row one"
            android:textSize="15pt" />

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="row two"
            android:textSize="15pt" />

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="row three"
            android:textSize="15pt" />

        <TextView
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="row four"
            android:textSize="15pt" />
    </LinearLayout>

</LinearLayout>

Specify android:weightSum for the parent layout and also android:layout_height="0dp" for child layouts. Please try this. Hope this would help.