So the basic idea is: launch an AsyncTask making your service call, show a nifty progress dialog while the task thread is running, and have the task’s result be posted back to your activity once it completes. Cool, but what if the user decides to rotate the screen while your task is running? Or a phone call comes in, interrupting your app, and Android decides to kill it? Both these actions will effectively terminateyour activity, and recreate it when resuming (yes, a screen rotation kills your activity, very clever, isn’t it?). Unfortunately, any AsyncTask that was still running now holds a stale reference to your activity, because the restarted activity will be an entirely different object in memory (and it will go through onCreate(), as if the activity had started for the first time). I’m not entirely sure whether AsyncTask will actually post back the data to the old activity object (if it was a weak reference, it may already have been garbage collected), but in any case, your “new” activity will never see it, because it’s a different instance.

Droid-Fu offers both support classes meant to be used alongside existing Android code, as well as self-contained, ready-to-be-used components like new adapters and widgets. The areas tackled by Droid-Fu include: application life-cycle helpers support classes for handling Intents and diagnostics better support for background tasks super-easy and robust HTTP messaging powerful caching of Objects, HTTP responses, and remote images custom adapters and views I suggest you read this introductory article, and anything that follows.

Consumers want immediate access to what’s relevant and QR codes are being used to make that possible.

Bar codes are linear one-dimensional codes and can only hold up to 20 numerical digits, whereas QR codes are two-dimensional (2D) matrix barcodes that can hold thousands of alphanumeric characters of information. Their ability to hold more information and their ease of use makes them practical for small businesses.

When you scan or read a QR code with your iPhone, Android or other camera-enabled Smartphone, you can link to digital content on the web; activate a number of phone functions including email, IM and SMS; and connect the mobile device to a web browser.

For completeness we really should handle the possibility of the task getting cancelled. This can happen when the user navigates away from the app and the task is killed before its completed. This will cause the onPostExecute() method to not be called and so the onRefreshComplete() method won’t be called. Depending on how the user navigates through the app, they could return to this activity without going through the complete onCreate() lifecycle, and you’ll end up with the screen still showing the “loading” progress message in the header. This is common when using tabs between multiple ListViews. Also, the documented best practices for implementing an AsyncTask says that in long running background work you should periodically check if the task has been cancelled and try to gracefully quit your work and exit. So let’s get all of that in there.

This is a compact and straightforward library for parsing SVG files and rendering them in an Android Canvas. By using vector art, the pain of supporting various screen sizes and densities in Android can be reduced. This was the library used to render the artwork and the interface of Androidify. The project also includes a Live Wallpaper app extracted from Androidify. The app shows off the SVG library, and demonstrates the rendering pipeline used to draw the Androids.

I'm Johan, a Stockholm, Sweden based Web and Android developer that love APIs, hackathons and open source. Contact me using Twitter or email.

Google 员工 Damon Horowitz 曾经是多家创业公司的联合创始人。他最近一次创业是 Aardvark 问答网站，然后就被 Google 收购。Damon Horowitz 的有趣之处在于，他拥有一个哲学博士学位，在公司内部大家称他为“哲学家”。

一旦话题涉及到了科技领域的伦理道德，Horowitz 就会问大家是喜欢 iPhone 还是 Android 。当大多数人回答说“喜欢 iPhone ”时，Horowitz 就开玩笑地说你们是“冤大头”，只是因为外表漂亮而选择设备

这个结果很可怕。我们更在乎手机功能的强大，而不在乎这些功能是否在道德框架之内。”

The workspace in a viewgroup which creates virtual views (or screens). The user is able to navigate between screens by swiping the screen with his finger.

MergeAdapter accepts a mix of Adapters and Views and presents them as one contiguous whole to whatever ListView it is poured into. This is good for cases where you have multiple data sources, or if you have a handful of ordinary Views to mix in with lists of data, or the like.