<uses-library android:name="string" />
<application>
All of the android packages (such as android.app, 
android.content, android.view, and android.widget) 
are in the default library that all applications are automatically linked 
against.  However, some packages (such as maps and awt are 
in separate libraries that are not automatically linked.  Consult the 
documentation for the packages you're using to determine which library 
contains the package code.
