I read an email from an Android email list. There is a person to ask about the permissions. I think there is some people who are from Windows Programming background. The permission are set from OS. We don't need to state in our code about which permissions we need. But in Android, that is different. You need to set the permission you need to use in AndroidManifest.xml.

Javadoc for permissions: http://developer.android.com/reference/android/Manifest.permission.html
Security documentation for Android: http://developer.android.com/guide/topics/security/security.html

I believe those two documents are worth to read for us.