z2sky solutions: 2012

Saturday, November 17, 2012

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:

Services Lifecycle Diagram from developer.android.com:

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.

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

Saturday, November 10, 2012

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:

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

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/

Saturday, June 23, 2012

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

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