howdy, John!

it worked!

and howdy, Gabriele!

Hi :)

John: you narrowly got in first, so... do you have a question?

so, shall I kick off? i've got one question straight away...

How can I install / remove s/ware from the Android device programmatically?

do you mean from an Android app running on the device?

or do you mean from some software running on a PC attached to the device

?

could be - i'm an Android newbie... I'm thinking via some google API on the device?

NOT on a PC attached, that's not an option for me.

from on the device, you can *initiate* an install or uninstall, but the user has to accept some dialogs to complete the process

ok, sounds cool. am I allowed to continue asking questions? :-) or is this round robin?

you initiate an install via an ACTION_VIEW or ACTION_INSTALL Intent with startActivity(), and initiate an uninstall via ACTION_UNINSTALL_PACKAGE with startActivity()

it is round-robin, to help maintain my sanity

:-)

in that case.... next please!

and, with that... Gabriele: do you have a question?

I've solved the problem of yesterday, anyway, now I have a new one: if I select a bookmark from my listView (inside my BookmarkFragment) and I press a button to delete it, it works, but if I rotate the screen, wait and then press the delete button, I get: "java.lang.IllegalStateException: Content view not yet created" on line "ListView l = getListView();", have you an idea of why this can happen?

hmmm... I just answered a question on that on StackOverflow recently... hold on...

ok, thank you

take a look at the UPDATE section of my answer

yes, I will read it, you can continue with John, thank you :P

OK

John: do you have another question?

ok, via ACTION_INSTALL - can the s/ware be hosted anywhere or must it be on play... and are installations secure? e.g. HTTPS.

ACTION_INSTALL is for APK files already downloaded by you to the device and available via a local file

how you download that APK file is up to you

though the file will need to be world-readable long enough to do the install, as the installer runs in a separate process from yours

you cannot directly trigger an install from the Play Store, though you can link users over to an app in the Play Store if you wish

getting the file to the device is super easy then? e.g. if I have a URL I can simply read from that and save it on device, right?

hmmm change "save it on the device" to "save it within the sandbox" I suppose....

generally yes -- standard Java network I/O works

ok, semaphore time - switch to Gabriele...

DownloadManager handles edge cases like failover from WiFi to mobile data, but not via SSL and the resulting APK has to go onto external storage (not internal storage)

Gabriele: do you have another question?

OK, John -- back to you

no, I'm still reading and checking

(Gabriele: I thought that might be the case...)

ok

does Play have an API to search stuff in it's store?

there are no official Play Store APIs

official...

(eheh :) )

:-)

so, no guaranteed API stability over time, or are we talking utter hack here?

if you poke around, you will find people who have cracked the protocol between the Play Store client and server

I avoid this like the plague, as it (at least used to) violate terms of service

right, my thinking too.

so I don't know much about the details

I have begged Google repeatedly to open this up

but, no luck to date

i'll assume that this also answers my next question; there's no way to initiate play transactions via API either...

define a "play transaction"

buy a piece of s/ware. good point though.... there's usually a difference between accessing free and paid for apps on these things.

again, you can link the user over to the Play Store app screen for a particular app

if the user clicks on Buy, they'll go through the normal purchase process

but you cannot click Buy for them

ok - So i cannot "buy"on the play store on behalf of a user… are there coupon codes?

then, after that - over to G...

no

though they have set up physical gift cards -- it's possible that there is an online analogue that I missed

but you have no way of helping the user use one, anyway

because that is all inside the Play Store app

ok, sounds like a nightmware

nightmare even..

(BTW, Gabriele: chime in when you have a question)

it's more that it's a closed box

(I'm there)

OK, Gabriele: your turn!

Hm, you say that this happen because I'm not gone through onCreateView(), but in my case I'm gone (I've checked it using a breakpoint), so I can't understand, why this happen? the listview should be there

you went through your original onCreateView()

but you rotated the screen

which destroyed the activity and its views

the new activity apparently has not yet called onCreateView() on the (possibly new) fragment

but after the screen rotation, i went again through onCreateView

then your ListView cannot be null

TT

infact I'm also waiting a lot of time, after the rotation, before press the delete button

and I think it should be not null

is the ListFragment on the screen at the time you press this delete button?

yes

well, you clearly have the ListView, then, because you can see it

hence, I do not know why/how you would get that exception, sorry

ok, thank you, I will try to understand it :P

John: do you have another question?

I've heard that it's possible to control certain settings on Android via exchange services - what settings can be controlled and do you know of a good place i can read about this (I assume it takes far too long to answer here)?

I know nothing about Exchange services

I don't even know where to tell you to look, as there is nothing in the Android SDK about Exchange

that's a question for your device manufacturer, I guess

ah, wrong word perhaps... ActiveSync?

likewise

drat. ok.

:-)

Android the OS has stuff for that, but it's not exposed to us as developers, and hence, if there is documentation, I don't know where it would live

OK - Is there an API to obtain the list of installed applications?

there are methods on PackageManager for that

specifically, getInstalledApplications()

what about getting hold of all the gory hardware details, e.g. amount of RAM installed, amount used, type of network connectivity, name of current network, GPS location? API's for that stuff too?

ConnectivityManager and LocationManager for the latter stuff

RAM is a complex problem

what do you mean?

complex?

I would recommend reading the following StackOverflow answer from Dianne Hackborn: http://stackoverflow.com/questions/2298208/how-...

ok, cheers, I'll squirrel that link away

quoting the first paragraph: "Note that memory usage on modern operating systems like Linux is an extremely complicated and difficult to understand area. In fact the chances of you actually correctly interpreting whatever numbers you get is extremely low."

Gabriele: do you have another question?

not for now, thank you

OK, if you come up with one, chime in

John: feel free to continue if you have other questions

excellent, will do.

ok, next Q coming...

(gotta reform it so I don't give everything away)...

there's a permission called BRICK, allowed only when the apk is signed by the same cert as the firmware - is this still available on 4.2 and what does the permission provide access to?

yes, BRICK still exists

however, I have never found what it controls

AFAIK, it's an Easter egg

I tried searching the source code for places that use it and came up with nothing

i was wondering if it allowed me to initiate a remote wipe of the entire device for example.

no, though you can do wipes via the device admin APIs

omg, I forgot to ask - what device admin API's exist? :-)

you can set minimum requirements for the device PIN/password and force re-entry of a password

you can set the max amount of inactivity before the device re-locks

you can require full-disk encryption and lead the user to go through that

you can disable the camera

on 4.2, you can disable lockscreen widgets and lockscreen camera access

you can immediately lock the device

and you can initiate a wipe

thanks! is there an easy way to detect if the device is rooted / jailbroken?

not really

you can poke around and see if you can find an 'su' binary

but that's not definitive either way

ok, thought it might be something like that - but give it's sandboxed - how could i poke around?

try running it

don't I have access only to a "local" filesystem

:-)

duh

honestly, I'm not an expert on rooting, so I don't know the details of how you run apps as superuser, other than a 'su' binary is involved

in Android, am I right when I say the API's to read/write are entirely sandboxed? e.g. if I tested for /usr/local/sbin/su - I would only hit the local FS of the app?

it won't be in /usr/local/sbin, because there is no /usr/local/sbin

Android's filesystem is... distinctive

lol

basically, you have full access to your corner of internal storage

on 4.1 and below, that's /data/data/your.app.package.name.here

think of that as your HOME directory from a Linux standpoint

but you're not chroot'd there

you will have limited access to things outside of that location, such as /proc and /dev

stuff that they couldn't really lock down very well

but you cannot get to other apps' /data/data/... directories

ok, i think - from my side that's a lot of info I can use to generate more questions.

OK

so for now - that's all I have. nice and easy!

if either of you have any other questions during the remainder of the chat, just ask

Mark, are you available for on-site training in Switzerland?

i'd have 5 devs to train in Android.

we can talk about that offline via email if you wish.

yes, let's discuss this via email

in short: probably yes

hm it seems the problem was the casting of getActivity (inside ModeActionHelper) to WikiApp (which is my main activity)

I am surprised that a cast caused the particular exception you received

anyway now I have a new problem, in onCreate I have oWikiAdapter = new MyPagerAdapter(getSupportFragmentManager(), this); but after it is null, how is this possible?

:(

which is giving me NullPointerException

what is "it" in the phrase "after it is null"

?

but after, in my method call, it's null

what is "it's" in your preceding sentence?

it = the adapter, oWikiAdapter

one thing isn't super clear to me... you mentioned that there's no official Google Play Store API - which makes it hard to search/list/query the store items. Is that correct?

then either you are setting it to null, or this is a new instance of whatever is calling your constructor and it has not gotten to that line yet

as in, there's no way to take URLS from the store and present them to the user in another app for example...

John: yes

if you know the developer or app name, you can construct a URL

I'm setting it to null only inside onDestroy hm

oh, after commenting oWikiAdapter = null, inside onDestroy I get again java.lang.IllegalStateException: Content view not yet created

by the time onDestroy() is called, I suspect that onDestroyView() of the fragments will have been called, though I am not completely certain

Mark, thanks - I'll be in touch via email.

G; I wish you the best in your coding endevours!

John: I just sent you an email to kick off that discussion

I've put a breakpoint inside onDestroy(), but it's raised only in the moment I'm changhing orientation

that makes sense, as your old activity is being destroyed as part of the configuration chagne

er, change

I have: onDestroyView when the orientation changes, then onCreateView, then getListView is null :(

I have no explanation for that behavior, assuming that you are calling through to the superclass onCreateView()

though, check to make sure you are dealing with the right objects

if this fragment is not retained, then onDestroyView() is called on one instance, and onCreateView() is called on a different instance

if you are trying to do things with the old instance, it will not have a ListView

how can I be sure to use the correct istances?

in theory, that should be happening automatically

be sure not to pass fragments around in onRetainNonConfigurationInstance()

no, I don't have it

I'm getting the activity inside my fragment using this: private static WikiApp oActivity = null;

there's your problem

should I use (cast)getActivity?

but before, with the cast I had the same problem :(

you should get rid of that line entirely

never put activities in static data members

in this case, probably you are referencing the old activity, from before the configuration change

and hence the old fragments

ok thank you, I will try to understand these things for the next time :P

see you the next time, thank you very much

OK

the next office hours chat is next Tuesday, once again at 10am Eastern

nice, thanks

have a good day :)

thanks - i left you an email re: training.

yes, I see it

I'll respond within the next couple of hours

any other questions for the chat?

nope - kill it. thank you.

OK