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I want to receive time tick in a widget, and tried the code in this link, and it works great on my kindle fire which runs a custom ROM of Android API level 15, but sometimes the time is wrong on my phone which runs Android 4.2 API level 17.

my confusion is the same as a comment below the article

This is completely unreliable. Android will terminate your process whenever it wants after the onUpdate() method returns, causing the BroadcastReceiver and Application to both vanish.

can anyone explain or testify the code?

molikto
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1 Answers1

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I want to receive time tick in a widget

That is not possible in a reliable fashion.

and tried the code in this link

That code is completely unreliable, as I noted in a comment on the blog post.

it works great on my kindle fire which runs a custom ROM of Android API level 15

You have not run your app for long enough. It will fail on your Kindle Fire as well.

but sometimes the time is wrong on my phone which runs Android 4.2 API level 17

It is possible that Android 4.2 is more aggressive about terminating processes with no active components, which is why it is failing faster for you on your phone. However, it is guaranteed to fail, for the reason I outlined in my comment on the blog post and that you quoted in your question.

Android apps run as OS processes, as programs do in most modern operating systems. Android will terminate processes as needed to reclaim RAM to use for other processes. Android will eventually terminate the process for your app, at which time your registered receiver evaporates.

In the meantime, if onUpdate() gets called multiple times, you will register multiple receivers for the broadcast, each additional receiver adding that much more overhead.

CommonsWare
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  • yes, I call it on onUpdate(), because I tried to do it in onEnabled(), but it is more unreliable, but every time I unregister first and catch the exception if the receiver is not registered, I noticed API level 17 introduced a new view TextClock, will it do the work? many thanks for your excellent answers (for all SOF questions). – molikto Dec 08 '12 at 13:29
  • @pirriperdos: AFAIK, `TextClock` is not available to app widgets, though you are welcome to try it. – CommonsWare Dec 08 '12 at 13:31
  • the AOSP digtal clock wigdet for 4.2 use TextClock, I have checked the code... I'll try figure it out myself – molikto Dec 08 '12 at 13:42
  • may you look at [this question](http://stackoverflow.com/questions/13429062/timestamp-based-sync-how-to-reduce-the-mobile-data-usage)? It confused my for a while and no one has answered me, thank you! – molikto Dec 08 '12 at 16:38