How to make fixed XML layouts?

Question

I have two layouts. Actually 5, 3 vertical one below another and in the middle one I have 2 layouts side by side. I need them to be fixed size, so they do change. But as soon as I place a button i one of them, they change size, as you can see on the picture below. How to make them not change? Anyway, here's my code and pictures.

<?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:orientation="vertical"
    android:weightSum="20" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_weight="3" >
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="15"
        android:orientation="horizontal" >

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="vertical"
            android:layout_weight="1" >
        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="vertical"
            android:layout_weight="1" >
        </LinearLayout>

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_weight="2" >
    </LinearLayout>

</LinearLayout>

Answer 1

Try changing the two inner layouts to this:

Option #1 : This will fix the layouts horizontally, not vertically

<LinearLayout
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:layout_weight="50" >
</LinearLayout>

<LinearLayout
    android:layout_width="0dp"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:layout_weight="50" >
 </LinearLayout>

Option #2 : This will fix the layouts in both directions

It is very inefficient to use LinearLayouts with nested weights. Instead, change your root view to a RelativeLayout and get rid of the weights. Please note that this isn't a 100% complete solution but it will definitely get you started. This will put the first LinearLayout at the top of the layout and the last LinearLayout at the bottom of the layout. The middle one will always be below the top view and below the bottom view.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout android:id="@+id/top"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:orientation="vertical">
    </LinearLayout>

    <LinearLayout android:id="@+id/middle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/top"
        android:layout_above="@+id/bottom"
        android:orientation="horizontal" >

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="vertical"
            android:layout_weight="1" >
        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:orientation="vertical">
        </LinearLayout>

    </LinearLayout>

    <LinearLayout android:id="@+id/bottom"
        android:layout_alignParentBottom="true"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">
    </LinearLayout>
</RelativeLayout>

Answer 2

尝试将layout_weight更改为中间线性布局的两个子线性布局的0.5。