Android Services

Android Services

A Service is an application component that can perform long-running operations in the background and does not provide a user interface. 

• Another application component can start a service and it will continue to run in the background even if the user switches to another application. 
• Additionally, a component can bind to a service to interact with it and even perform interprocess communication (IPC). 
• For example, a service might handle network transactions, play music, perform file I/O, or interact with a content provider, all from the background

Detailed documentation on services can be found from Google Android Services Documentation

Other examples and articles on Android Services:

• http://www.vogella.com/articles/AndroidServices/article.html
• Services example from Marakana
• http://saigeethamn.blogspot.com/2009/09/android-developer-tutorial-for_04.html

Services Lifecycle Diagram from developer.android.com:

Android Data Storage

Android Data Storage

Android provides several ways to store the data. More details can be found from http://developer.android.com/guide/topics/data/data-storage.html

• Shared Preferences
• This provides a quick and easy way to store key-value pair based primitive data across multiple sessions of the app; DOES NOT preserve the data across power cycle.
• Examples/Tutorials
• http://www.vogella.com/articles/AndroidFileBasedPersistence/article.html
• Internal Storage
• Stores the data on the internal storage of the phone. Preserves the data across the power cycles.
• Files created gets removed when the user uninstalls the app
• This data is app-specific data; Not world readable
• E.g. Example of Internal Storage on Android
• External Storage (e.g. SD Card)
• This is saved/restored in similar way as the internal storage
• HOWEVER -- IT IS WORLD READABLE; So do not save sensitive data
• E.g. External Storage example on Android
• SQLite Databases
• Android has full support for SQLite
• Any database created in the app, can be accessed by the name from any class in the app
• Not outside the app
• To Create a new database, create a subclass of SQLiteOpenHelper
• E.g. 
• http://www.vogella.com/articles/AndroidSQLite/article.html
• http://www.androidhive.info/2011/11/android-sqlite-database-tutorial/
• Cloud storage
• 
  
• Content provider
• It is the only way to share the data across multiple apps - selectively
• Content provider and Content resolver provides an interface to the app to talk to the Contents, which could be SQLite database or Internal/External storage or on cloud
• Managed Queries is another important concept to understand with ContentProvider with the queries; Managed Queries based cursor will get updated automatically as and when the activity goes through it's life cycle
• Good Blog: http://www.vogella.com/articles/AndroidSQLite/article.html#contentprovider

Android Intents

Android Intents

• Good article on Android Intents - http://www.vogella.com/articles/AndroidIntent/article.html
• Google documentation - http://developer.android.com/guide/components/intents-filters.html
• Few more articles/Videos
• http://www.androiduipatterns.com/2011/06/android-intents-apps-talking-to-each.html
• Videos on android Intent: 
• http://www.youtube.com/watch?v=lqopIf-bA54
• http://www.youtube.com/watch?v=cv2bh53IL_Y
• 
  

Android Basics

Android Basics

In this blog, I am trying to list some android basics including the details about the android architecture

• What is android
• Android Architecture

Android Devp

Developing Android Applications

When I started learning android development a couple of years ago, the web resources like blogs and youtube videos were the most handy resources for me to quickly find answers to my howtos! However, I still had to spend great amount of time to pick and choose what is more relavant. In this always work-in-progress blog, I am trying to list as many howtos as I can - which could come handy while working on android development

Refer to my another blog on how to setup the android app devp env to start with HelloAndroid app: http://myz2sky.blogspot.com/2012/06/android-development-using-eclipse.html

Check my github for the example apps and some useful links on it's wiki - https://github.com/ddesai/

howtos

I would like to use this page to keep it populated with tons of useful howtos

• Eclipse
• How to get github or any other git repo plugged-in with Eclipse for version controlling your code while developing it in Eclipse
• http://www.vogella.com/articles/EGit/article.html#git 
• Android Development
• Coming soon
• HTML5 and jQuery
• Coming soon
• iPhone App development
• Coming soon
• Python Frameworks
• Django
• Download and install 
• Download the Django from here - https://www.djangoproject.com/
• Download and install Python - e.g. 2.7 -  http://www.python.org/download/releases/2.7.2/
• Set the env variables/paths to point to the Python installed dir
• Go on your command shell, go to the directory where you downloaded Django and type "python setup.py install"
• Google App Engine
• https://developers.google.com/appengine/

• Virtual Machine and infrastructure
• How to mount an ISO image as a virtual drive on Windows 7
• Download and install this Freeware - Virtual Clone Drive (VCD)
• http://www.slysoft.com/en/virtual-clonedrive.html
• Right click on your .iso or any such image and mount it as a drive using the VCD
• Run Virtual Machine software on Win7 
• Among several available, I would pick the freeware - Virtualbox 
• Download it from here -  https://www.virtualbox.org/wiki/Downloads
• Get the Virtualbox for Windows - as pointed by the link on teh page above
• Get the extension pack
• Install both of above. It is quick and easy
• How to use it - a nice example here: 
• http://www.youtube.com/watch?v=rKnMRdAH4R8 

Android Development using Eclipse

• Setting up Android Development Env on Window system
• Download "Eclipse IDE for Java EE Developers" Eclipse 
• from  http://www.eclipse.org/downloads/
• It gives you installable ZIP file. So extract it wherever you would like your eclipse binary to stay
• If you try to run "eclipse.exe", it will not work without JDK on your system
• e.g. C:/eclipse 
• Download and install JDK if you dont already have one 
• http://www.oracle.com/technetwork/java/javase/downloads/index.html
• Remember the directory for your jdk 
• e.g. C:\Program Files\Java\jdk1.7.0_05
• e.g. C:\Program Files\Java\jre7
• Download and install Eclipse Plugin for Android Development (ADT Plugin) and Android SDK 
• http://developer.android.com/sdk/installing/installing-adt.html 
• After you restart the eclipse first time after installing ADT Plugin, it will ask you to download the latest Android SDK and ask you for the target directory. Provide the directory where you want to install it and remember it - e.g. "C:/android-sdks" 
• It will install "Android SDK Platform" and "Android SDK Tools" - like debugger etc. Just follow the prompts until it completes the installations. 
• Create and Run First "Hello World on Android" app using Eclipse
• http://developer.android.com/training/basics/firstapp/index.html
• http://androidarmory.blogspot.com/2011/04/creating-your-first-android-app.html 
• My Example is attached

• Tips
• When you setup the Android Emulator - AVD as described in the steps given in build your first app, you might run into a problem below when you create the AVD
• "Unable to find a 'userdata.img" file for ABI armeabi to copy into the AVD folder" 
• To solve this, you would need to install the package "ARM EABI * System Image" from Eclipse-->Window-->Android SDK Manager ; Basically this sets up your system target CPU ISA to ARM, letting you run your app on ARM target for android.
• When you do that, it would also give you an option to install "Intel x86 Atom System Image". Doing so would let you run your emulator for Intel Atom target for Android
• Since I have Android 2.1 phone where I want to test my app, I am also downloading Android 2.1 (API7) which I can use to develop an app that runs on Android 2.1