Re: [android-developers] parcelable again: passing object BACK through activity stack
On Fri, Sep 23, 2011 at 9:53 PM, Streets Of Boston flyingdutc...@gmail.comwrote: 1) The onActivityResult will have a result-code of RESULT_CANCELED and its 'Intent data' parameter will be null. 2) Yes, you can pass back any Intent, even the one that started the child-activity. You don't need to create a brand new one. When an Intent is passed back or forth between Activities (starting an activity / setResult+finishing), the other end (getIntent() / Intent in the onActivityResult) doesn't get the exact same *instance *of the Intent. Instead, it'll get a copy of it as an Intent with the exact same contents. As a comparison: Intents are passed by copy, not by value or reference :-) Thanks, that makes sense. However I have one more question if you don't mind asking concerning onRestart(), onStart() and onActivityResult(). I am using onActivityResult() in acitivty A to store data from acitivty B in a database. Is it safe to refresh the screen widgets with the data in onActivityResult() or is it better to do this inside onStart()? Plus, which gets called first, the asynchronous onActivityResult() or onStart(). This is what has been puzzling me lately. Thanks for your insight, John Goche -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
On Sun, Sep 25, 2011 at 6:26 AM, John Goche johngoch...@googlemail.comwrote: Is it safe to refresh the screen widgets with the data in onActivityResult() or is it better to do this inside onStart()? It is safe and preferred - how would you know you were coming back from a result in onStart() ? Plus, which gets called first, the asynchronous onActivityResult() or onStart(). This is what has been puzzling me lately. Put a log statement or break point in each and see. - TreKing http://sites.google.com/site/rezmobileapps/treking - Chicago transit tracking app for Android-powered devices -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
On Thu, Sep 22, 2011 at 7:15 PM, John Goche johngoch...@googlemail.comwrote: Not sure how to try this out on the emulator. F12 or F11 or something causes the emulator to rotate. See the emulator section in the Docs. Since the Intent is returned to the parent activity inside onActivityResult, what is the difference in using setResult and using putExtra in Activtity B on the Intent to pass back a custom result parameter to Activity A? Difference compared to what? - TreKing http://sites.google.com/site/rezmobileapps/treking - Chicago transit tracking app for Android-powered devices -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
You can try this on the emulator. Hit Ctrl+F11 and you'll 'rotate' the device. setResult does not immediately return results back to its parent activity (You can call setResult many times: only the last call to setResult will be effective, superseding all previous calls) The Intent you use when calling setResult will be the same Intent passed to the parent's implementation of onActivityResult later. Only when your child-activity finishes (call 'finish()' or the user hits the Back-key/button), then onActivtyResult will be called with same the Intent that was used by the last call to setResult. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
On Fri, Sep 23, 2011 at 3:27 PM, Streets Of Boston flyingdutc...@gmail.comwrote: You can try this on the emulator. Hit Ctrl+F11 and you'll 'rotate' the device. Yes, I saw the problem pop up with my onRestart() called when I wasn't expecting it. I can see the problem here with onRestart() being called when I didn't expect it to (for all activities on the activity stack?) when the screen is rotated. Thanks for pointing it out. I can also see the emulator bug whereby I have to relaunch my application to exit landscape mode and get back to portrait mode. setResult does not immediately return results back to its parent activity (You can call setResult many times: only the last call to setResult will be effective, superseding all previous calls) This part is clear. The Intent you use when calling setResult will be the same Intent passed to the parent's implementation of onActivityResult later. Only when your child-activity finishes (call 'finish()' or the user hits the Back-key/button), then onActivtyResult will be called with same the Intent that was used by the last call to setResult. What is not clear to me at this point from the documentation is: 1. if I don't pass an intent to setResult(), ie. use the one-parameter version of setResult(), then will the null Intent be passed back to my onActivityResult callback function? 2. Can I pass activity B's intent back to activity A by a call to setResult and a call to finish() or do I have to create a new Intent in activity B to pass back to activity A in my setResult? Thanks, John Goche -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
On Fri, Sep 23, 2011 at 1:38 PM, John Goche johngoch...@googlemail.comwrote: 1. if I don't pass an intent to setResult(), ie. use the one-parameter version of setResult(), then will the null Intent be passed back to my onActivityResult callback function? 2. Can I pass activity B's intent back to activity A by a call to setResult and a call to finish() or do I have to create a new Intent in activity B to pass back to activity A in my setResult? This is the kind of stuff you learn by just trying it and seeing what happens =) - TreKing http://sites.google.com/site/rezmobileapps/treking - Chicago transit tracking app for Android-powered devices -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
1) The onActivityResult will have a result-code of RESULT_CANCELED and its 'Intent data' parameter will be null. 2) Yes, you can pass back any Intent, even the one that started the child-activity. You don't need to create a brand new one. When an Intent is passed back or forth between Activities (starting an activity / setResult+finishing), the other end (getIntent() / Intent in the onActivityResult) doesn't get the exact same *instance *of the Intent. Instead, it'll get a copy of it as an Intent with the exact same contents. As a comparison: Intents are passed by copy, not by value or reference :-) -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
Yes, the advice is indeed very good.
1. For the SQLite database bit, I think if parcelable is better than
serializable then
can I simplyparcel my nested object and write it as a row to the
database?
I think SQLite is going to be faster than shared preferences.
2. However at this point I am wondering what the difference is
in using onActivityResult versus simply coding onRestart like so:
@Override
protected void onRestart() {
// should be returning from activity
if (this.hasPushedActivityB) {
foo();
} else {
bar();
}
}
// further down
this.hasPushedActivityB = true;
// start new intent
startActivity(new Intent(...));
//...
private boolean hasPushedActivityB;
Anything wrong with this alternative approach?
--
3. I will look at result receiver even though I have used
a Globals class annotated with each parameter that needs
to be passed from screen to screen. Not sure, maybe using
result receiver is beter.
Thanks,
John Goche
On Thu, Sep 22, 2011 at 1:08 AM, Richard Schilling coderroa...@gmail.comwrote:
This is some good sound advice. If you don't want to
use startActivityForResult and onActivityResult then you can store your data
in some source of truth like the SQLite database, or even shared
preferences if you just have a few data items.
Richard
Streets of Boston wrote:
1. Try to avoid Serializable. It is very slow compared to Parcelable.
2. Take a look at startActivityForResult and onActivityResult.
3. If you reeeaaally need to update activity A about events from activity
B, consider putting your own subclass of ResultReceiver in the Intent's
'extras'. Then activity B can call 'send(...)' on that ResultReceiver and
this will be received in activity A as an 'onReceiveResult(...)' call-back.
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Re: [android-developers] parcelable again: passing object BACK through activity stack
Yes, a lot :) Try out your code using 'hasPushedActivityB' and then rotate your phone or, if it has a physical keyboard, slide out the keyboard: The activities will be recreated and your 'hasPushedActivityB' of the new activity A will be false, but the new Activity B will be showing. Just use onActivityResult.:) -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
On Thu, Sep 22, 2011 at 3:43 PM, Streets Of Boston flyingdutc...@gmail.comwrote: Yes, a lot :) Try out your code using 'hasPushedActivityB' and then rotate your phone or, if it has a physical keyboard, slide out the keyboard: The activities will be recreated and your 'hasPushedActivityB' of the new activity A will be false, but the new Activity B will be showing. Not sure how to try this out on the emulator. Just use onActivityResult.:) OK, but one more thing is not clear from the documentation at http://developer.android.com/reference/android/app/Activity.html under Starting Activities and Getting Results which states: When an activity exits, it can call setResult(int)http://developer.android.com/reference/android/app/Activity.html#setResult%28int%29to return data back to its parent. Since the Intent is returned to the parent activity inside onActivityResult, what is the difference in using setResult and using putExtra in Activtity B on the Intent to pass back a custom result parameter to Activity A? (There is an example here: http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/app/SendResult.html and then there is the NotesList application.) Thanks, John Goche -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
On Tue, Sep 20, 2011 at 5:38 PM, John Goche johngoch...@googlemail.comwrote: I think I'm gonna go for serialization and write the serialized object to a database in one row of text. That's the quick and dirty way of doing things I guess. Also, I'm done with Parcelable since I need to pass data back and forth. I've already reverted to passing a parameter in a global variable: it's the quickest and easiest way. I predict regret =) Good luck. - TreKing http://sites.google.com/site/rezmobileapps/treking - Chicago transit tracking app for Android-powered devices -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
1. Try to avoid Serializable. It is very slow compared to Parcelable. 2. Take a look at startActivityForResult and onActivityResult. 3. If you reeeaaally need to update activity A about events from activity B, consider putting your own subclass of ResultReceiver in the Intent's 'extras'. Then activity B can call 'send(...)' on that ResultReceiver and this will be received in activity A as an 'onReceiveResult(...)' call-back. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
This is some good sound advice. If you don't want to use startActivityForResult and onActivityResult then you can store your data in some source of truth like the SQLite database, or even shared preferences if you just have a few data items. Richard -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
[android-developers] parcelable again: passing object BACK through activity stack
Hello, I have two A and B and clicking on a button in A opens B. I pass an object from A to B using parcelable and the extras in the intent used to open B. Now I have the following problem: given that A is beneath B on the activity stack and will not be reopened, how do I pass the object from B back to activity A? Thanks for your help, John Goche -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
You probably should reconsider your approach. It sounds like you need a central data model, accessible from multiple activities: -- database -- file managed by: -- service -- some other singleton -- custom Application class Extras on Intents should be viewed much along the lines of GET parameters on Web pages. You wouldn't talk about passing a GET parameter back to some page in the user's history. On Tue, Sep 20, 2011 at 7:55 AM, John Goche johngoch...@googlemail.com wrote: Hello, I have two A and B and clicking on a button in A opens B. I pass an object from A to B using parcelable and the extras in the intent used to open B. Now I have the following problem: given that A is beneath B on the activity stack and will not be reopened, how do I pass the object from B back to activity A? Thanks for your help, John Goche -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- Mark Murphy (a Commons Guy) http://commonsware.com | http://github.com/commonsguy http://commonsware.com/blog | http://twitter.com/commonsguy Android Training...At Your Office: http://commonsware.com/training -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
On Tue, Sep 20, 2011 at 6:55 AM, John Goche johngoch...@googlemail.comwrote: given that A is beneath B on the activity stack and will not be reopened What do you mean A will not be reopened ? You're probably looking for startActivityForResult() and onActivityResult(). - TreKing http://sites.google.com/site/rezmobileapps/treking - Chicago transit tracking app for Android-powered devices -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] parcelable again: passing object BACK through activity stack
Perhaps I can use the Serializable interface and simply serialize On Tue, Sep 20, 2011 at 2:33 PM, Mark Murphy mmur...@commonsware.comwrote: You probably should reconsider your approach. It sounds like you need a central data model, accessible from multiple activities: -- database -- file managed by: -- service -- some other singleton -- custom Application class I think I'm gonna go for serialization and write the serialized object to a database in one row of text. That's the quick and dirty way of doing things I guess. Also, I'm done with Parcelable since I need to pass data back and forth. I've already reverted to passing a parameter in a global variable: it's the quickest and easiest way. Regards, John Goche -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
