Android developer road

So, I'm going through a quick Android developer course. The main target is to learn how to provide the best Android apps with minimal effort. Assumption is we all know Java ;-)

The start

A good starting point is:
http://developer.android.com/training/index.html

I don't recommend to read it all at the beginning. I would suggest:

• Getting started (http://developer.android.com/training/index.html)
• Building apps with content sharing (http://developer.android.com/training/building-content-sharing.html)

Others as needed, Best Practices for Interaction and Engagement (http://developer.android.com/training/best-ux.html) also helps.

The above gives you a rough overview. The real stuff comes in API Guides (http://developer.android.com/guide/components/index.html). I do recommend to read the first three sections:

• Introduction (http://developer.android.com/guide/index.html)
• App Components (http://developer.android.com/guide/components/index.html)
• App Resources (http://developer.android.com/guide/topics/resources/index.html)

This gives you a high level overview of how the Android works.

The lifecycle

You basically should have it at your desk. You will use it often. It's been reported to have some inaccuracies but it's still better than the Google provided simplified version.

(check out: https://github.com/xxv/android-lifecycle)

Codelabs

Google provides two interesting codelabs:

• Build a Material Design App with the Android Design Support Library (https://codelabs.developers.google.com/codelabs/material-design-style/index.html)
• Android Testing Codelab (https://codelabs.developers.google.com/codelabs/android-testing/)

If you have to provide some early results quickly, skip above readings and just do the codelab.

Other must-to-know

Butterknife - http://jakewharton.github.io/butterknife/ - saves you lot of boilerplate with binding view elements to variables.

Android ContentProvider Generator - it will save you a lot of time on boilerplate code - https://github.com/BoD/android-contentprovider-generator
Mosby - http://hannesdorfmann.com/mosby - if you go with MVP this is must to use.
Dagger - dependency injection framework - http://google.github.io/dagger/users-guide

And when you consider which Android version to support, check:
Android stats Dashboard - gives an overview of the Android version distribution - http://developer.android.com/about/dashboards/index.html

Learning

Code Examples

https://github.com/mgrzechocinski/dagger2-example
https://github.com/cgruber/u2020/tree/dagger2
https://github.com/frogermcs/DaggerExample

Blog Posts

http://www.future-processing.pl/blog/dependency-injection-with-dagger-2/
http://fernandocejas.com/2015/04/11/tasting-dagger-2-on-android
http://konmik.github.io/snorkeling-with-dagger-2.html
http://siphon9.net/loune/2015/04/dagger-2-0-android-migration-tips/
http://blog.gouline.net/2015/05/04/dagger-2-even-sharper-less-square

Google Identity Toolkit for Android - weird compilation error

I’m hacking tiny Android app, one of the libraries I use is Google Identity Toolkit (it’s super easy to integrate). A documentation states that a Play Services should be added as dependency:

compile 'com.google.android.gms:play-services:8.3.0'

For any non trivial application it’s going to be a problem resulting in below error (or similar):

Error:Execution failed for task ':app:transformClassesWithDexForDebug'.
> com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Process 'command '/usr/lib/jvm/java-8-oracle/bin/java'' finished with non-zero exit value 2

Search on Internet points to StackOverflow question: com.android.build.transform.api.TransformException. Apparently the bugs are related. The exit return code 2 is meaningless unless one has any clues. Anyway, the problem can be solved by replacing the dependency by:

compile 'com.google.android.gms:play-services-plus:8.3.0'
compile 'com.google.android.gms:play-services-auth:8.3.0'

I’ve opened an issue on Google Identity Toolkit - Android sample project asking for more documentation.
The error is related to a constraint of Android Dalvik runtime of to 65K Reference Limit. There are two solutions for the problem: decreasing the references (usually by chosing smaller dependencies, in our case subpackages instead of the full Play Services) and using so called multidex (some 3rd party blog).

Screenshot with Android powered device

As I own beautiful Samsung Galaxy Nexus, I'm sometimes willing to make some screenshot to blog, show a friend or send bug report to developers etc.
Galaxy Nexus has Android 4.0 (Ice Cream Sandwich) on board so I don't know how it is in older versions.

To make a sreenshot: hold Volume Down + Power buttons by about 2 seconds. After than the information about the screenshot should appear on your device.

Below is the screenshot of this post.