how start up other apps and help to fill the data on android
<p>I want to develop an app that help users to start up other apps which needs username and password,so I must start up other apps and help to fill the username and password into the login userface of the apps,
   for example,I want to start up an app that helps user to login the facebook and fill the username and password in the login userface of the facebook app in my app,now I only konw the name of the facebookapp,
   1.how to start up it in my app?(I don't know the package name of the app started up)
   2.when I have started the app,how to automatically fill the username and password?</p>
