How to get RelativeLayout working with merge and include?

Question

There is an issue with the include tag. Check: https://issuetracker.google.com/issues/36908001

To fix it, make sure you overwrite BOTH layout_width and layout_height when including, otherwise everything will be ignored.

See the more highly voted answer below. Mine is woefully outdated

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i can address one issue Justin raised: inability of RelativeLayout to manage positioning of an include (at least in this simple case, on a 1.6 emulator)

CommonsWare suggests wrapping the includes in a unique parent container, but does so in order to assist addressing & scoping identically named Views within Justin's includes

Each would have to have a unique parent container, and you would call findViewById() on that container (ViewGroup) rather than on the Activity.

In fact, you also must do it in order to get RelativeLayout to behave as expected:

This works (footer is well positioned):

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="fill_parent">
    <include android:id="@+id/header" layout="@layout/header"
        android:layout_alignParentTop="true" />
    <WebView android:id="@+id/webView" android:layout_below="@id/header"
        android:background="#77CC0000" android:layout_height="wrap_content"
        android:layout_width="fill_parent" android:focusable="false" />
    <LinearLayout android:layout_alignParentBottom="true"
        android:layout_height="wrap_content" android:layout_width="fill_parent">
        <include android:id="@+id/footer" layout="@layout/footer" />
    </LinearLayout>
</RelativeLayout>

This does not (footer is floating at top of screen):

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="fill_parent">
    <include android:id="@+id/header" layout="@layout/header"
        android:layout_alignParentTop="true" />
    <WebView android:id="@+id/webView" android:layout_below="@id/header"
        android:background="#77CC0000" android:layout_height="wrap_content"
        android:layout_width="fill_parent" android:focusable="false" />
    <include android:id="@+id/footer" layout="@layout/footer"
        android:layout_alignParentBottom="true" />
</RelativeLayout>

The bare footer include will not align to bottom of parent, without the surrounding LinearLayout.. I wouldn't call this expected behavior.

Additionally, the WebView appears to attach itself nicely to the header by ID, but I believe this to be illusion, due to it simply flowing below the header vertically. I also tried to set a button right above the footer include, but it got all floaty and wrong, too

RelativeLayout had more problems in 1.5, but i still like it :)

Man, this is old, but it seems to come up at the top of searches, so I'm going to comment.

I think the trick here is that the <merge> tag combined with the <include> tag essentially remove any sort of "parent" view group at that level. So then, who exactly are you asking to "layout_below" someone else? No one. There is no view at that level.

The <merge> tag takes the child views and pops them right into the parent of the <include> tag. You must therefore ask the children in the layout you're including to anchor themselves accordingly.

For positioning to work on RelativeLayout you need to set the layout_* parameters in the include file, not in the main layout file. That way

main_layout.xml

<RelativeLayout
  android:id="@+id/header"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content">
   ....
</RelativeLayout>

<RelativeLayout 
  android:id="@+id/footer"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
  android:layout_alignParentBottom="true">
    .....
</RelativeLayout>

<include layout="@layout/content_layout" />

content_layout.xml

<merge xmlns:android="http://schemas.android.com/apk/res/android">
<RelativeLayout
    android:id="@+id/content"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_above="@id/footer"
    android:layout_below="@id/header" >

    ....
</RelativeLayout>
</merge>

This is obviously not what us developers want, but it's the only solution I've found to avoid duplicating xml