Activity, subActivity, Intent and IntentFilters in android?

i still have a problem to develop a convenient app to the user. because i am struggling using the activities, intent and intent filters. www.developer.android.com/reference not fit for me to understand these things. can you suggest me a fine example code or 开发者_JAVA百科tutorial to understand how these things are getting worked.

If a book is an option, i recommend you Professional Android 2 Application Development by Reto Meier; imho is the best and updated Android book available out there.