To begin with android development, go to this developer's guide. This is the best place to start learning Android development.
After that, if you like to read books then you can go to this book site. You can find three books here, and the guy that wrote these books are pretty active on SO also(click on the android tag and then go to the top user list, you will see him at the top).
Also, try searching SO first before asking a question. Many users have asked this type of question before. Some references are given below -
- https://stackoverflow.com/questions/1114287/good-book-for-beginning-android-development
- https://stackoverflow.com/questions/475152/how-can-i-learn-android
- Learning Android dev due to curiosity
- How to go about learning the android framework
- https://stackoverflow.com/questions/4306663/which-book-is-the-best-for-android-self-learning
Best of luck :-) .
Edit
From the documentation -
Android provides several options for you to save persistent application data.
The solution you choose depends on your specific needs, such as whether the data
should be private to your application or accessible to other applications (and the user)
and how much space your data requires.
Your data storage options are the following:
1.Shared Preferences
Store private primitive data in key-value pairs.
2.Internal Storage
Store private data on the device memory.
3.External Storage
Store public data on the shared external storage.
4.SQLite Databases
Store structured data in a private database.
5.Network Connection
Store data on the web with your own network server.
To read more, go here.
Also from the documentation -
Android provides full support for SQLite databases. Any databases you create will be accessible by name to any class in the application, but not outside the application.
Here is an example of an Android client-server model. PHP is used in this example as scripting language.
Also, see the below question -
- Options for Client Server Communication in Android