聚會時間公告: 因應COSCUP 2011, Kalug 8月份休會一次

二月 2, 2011
» [Tech notes] Android API levels

The following table specifies the API Level supported by each version of the Android platform:

Platform VersionAPI Level
Android 2.39
Android 2.28
Android 2.17
Android 2.0.16
Android 2.05
Android 1.64
Android 1.53
Android 1.12
Android 1.01

The API Level identifier serves a key role in ensuring the best possible experience for users and application developers:
  • It lets the Android platform describe the maximum framework API revision that it supports
  • It lets applications describe the framework API revision that they require
  • It lets the system negotiate the installation of applications on the user's device, such that version-incompatible applications are not installed.

Applications can use a manifest element provided by the framework API — uses-sdk — to describe the minimum and maximum API Levels under which they are able to run, as well as the preferred API Level that they are designed to support.

Development Considerations

Application forward compatibility

Android applications are generally forward-compatible with new versions of the Android platform.

Because almost all changes to the framework API are additive, an Android application developed using any given version of the API (as specified by its API Level) is forward-compatible with later versions of the Android platform and higher API levels.

Application backward compatibility

Android applications are not necessarily backward compatible with versions of the Android platform older than the version against which they were compiled.

Reference

一月 23, 2011
» [solved] Unparsed aapt error(s)! Check the console for output

Today I wrote some codes for my Android application as usual, and I found a parsing error that says:

"Unparsed aapt error(s)! Check the console for output"

However, I didn't see any errors after checking all the files. So what is going on here? It happens when some *.out.xml files are generated before the entire project gets built for execution. How can this happen? It happens when you run the application when in a resource file.

The solution to this issue is simple: make sure you clean any post-built files before building your application for a run. To achieve this, go to Project --- Clean in the Eclipse menu and it will work again. Or, you can just delete R.java file. It will get created again and the problem is solved.

一月 22, 2011
» [Tech Notes] Android basics II - Android SDK building blocks

A few objects are defined in the Android SDK that every developer needs to be familiar with. There are the building blocks of your android applications.

The most important ones are: Activities, Intents, Services, and Content Providers.

Activities - represents a user interface screen. Applications can define one or more activities to handle different phases of the program.

Intents - a mechanism for describing a specific action, such as "pick a photo". Everything has to go through Intents before creating activities or actions.

Services - a service is a task that runs in the background without the user's direct interaction, similar to a Unix daemon.

Content Providers - a set of data wrapped up in a common API to read and write it. This is the best way to share global data between applications.

一月 21, 2011
» [Tech Notes] Android Basics I - Android System Architecture

Android system architecture:

Get get the big picture of system architecture, please check out this documentation online. To sum up, there are four primary layers for the software system - Linux Kernel, Libraries and Android Runtime, Application Framework, Applications and Widgets.

This concept is essential because you need to know what layer (s) you will be dealing with when developing apps, making your own frameworks and libraries or even modifying Linux Kernel. For application development, you will not see Linux Kernel, all you can see is Application Framework and Application layers.

Android System Architecture

support:

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