关于android的id

当引用Android的资源ID（非本地资源ID）时，必须机上android包名，使用TabHost控件时就要如此操作：

When referencing an Android resource ID, you do not need the plus-symbol, but must add the android package namespace, like so:

With the android package namespace in place, we're now referencing an ID from the android.R resources class, rather than the local resources class.

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

<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="5dp" >

<TabWidget
android:id="@android:id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content" />

<FrameLayout
android:id="@android:id/tabcontent"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp" />
</LinearLayout>

</TabHost>