ClassNotFoundException for android.view.Space when

I'm having an issue running my application when certain elements exist in the layout of my activity. I have the following layout, and I have issue when I include the "Space" element:

<?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" >

<Button
       android:id="@+id/button1"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:layout_alignParentBottom="true"
       android:layout_alignParentLeft="true"
       android:text="@string/foursquare" />

<Button
      android:id="@+id/button2"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_above="@+id/foursquare_button"
      android:layout_alignParentLeft="true"
      android:text="@string/yelp" />

<Space
    android:layout_width="match_parent"
    android:layout_height="100px"
    android:layout_weight="0.18" />
</LinearLayout>

The error I get is this:

11-26 11:14:09.875: E/AndroidRuntime(10485): FATAL EXCEPTION: main
...
11-26 11:14:09.875: E/AndroidRuntime(10485): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.infoit.nfc.activity/com.infoit.nfc.activity.ViewTag}: android.view.InflateException: Binary XML file line #23: Error inflating class Space
...
11-26 11:14:09.875: E/AndroidRuntime(10485): Caused by: android.view.InflateException: Binary XML file line #23: Error inflating class Space
...
11-26 11:14:09.875: E/AndroidRuntime(10485): Caused by: java.lang.ClassNotFoundException: android.view.Space in loader dalvik.system.PathClassLoader[/data/app/com.infoit.nfc.activity-2.apk]
...

If I remove the Space element everything is peachy keen. Somehow it's not able to find the Space class even though I thought defining the xmlns would solve the issue. I feel this is something simple, but I am missing it.

回答1:

The xml file needs to refer to existing widgets either defined by the platform or by your own project, and Space is not a standard Android widget. Try replacing it with View instead.

回答2:

Space was introduced in API 14 but it's also available from android support v7:

    <android.support.v7.widget.Space
            android:layout_width="match_parent"
            android:layout_height="12dp"/>

By the way:

use dp instead of px
no need of secify the android:layout_height in a vertical LinearLayout with weight

回答3:

The other answers didn't work for me. Finally, I changed it to v4 like this:

android.support.v4.widget.Space

and it worked fine.

Class reference: https://developer.android.com/reference/android/support/v4/widget/Space.html