Androidology - Part 2 of 3 - Application Lifecycle

[apnudi]

I love this video, have shown it to many friends and enemies :)

[L00kng]

Fascinating. Thank you!

[kroggwaff]

4:19 OMG he's a ghost!

[apnudi]

@kroggwaff lol

[MrOooMooo]

But I feel extremely rapidly after you run the program task killer

[aelzin]

What's with the low resolution?

[janjiss]

Thank you! This encouraging me to get my hands dirty with android. This is brilliant programming ideas that you guys have done!

[fireicer]

This is quite a small masterpiece superb and impressive programing from google on this

[NaterBoxs]

thanks for the video. really helps explain the way the tasks are managed.

[NaterBoxs]

No matter what Verizon says, you dont need a task killer. Verizon pushes something that is unnecessary.

[mcsnaperville]

Like this presentation easy to follow and understand, good job

[DrnkSqrrlProductions]

I was doing it all wrong with my new Droid X. No more task killers for me!

[OhioCity]

I love the animated gif flame rows on this vid.

[nashadaily10]

you are an android

androidology

you are series of androids and new adroids

new version of androids

[Greenway9778]

Great Explaination to level set how things work behind the scenes.

[achana999]

awesome tutorial !!

[MixPix]

Great video to demonstrate that you don't really need a Task Killer in most cases.

[welpen2006]

The video is of poooooooooooooooooooooor quality. And the design of Google G1 looks like a US-$ 10,- device (even those look sometimes better)...traaaaaaaaaaaaaaaaaa­aaaaaash!

I will buy a Google device in 10 years when they have developed it further. Because Android has certainly some advantages over the iphone.

[crdowney1]

why save the home state, if you are never going to kill and resurrect it?

[mrbigberd]

You save the state so if there is an error or a crash, your settings and savings are okay

[crdowney1]

@mrbigberd thanks for the answer.

[Born2live88]

Loving it!

[zinkkrysty]

Excellent! Plain English explanation of Android, this rocks!

[xIamRightx]

@mlanovoy- Though I do agree that Java is superior to C++ in some ways, you are just proving to them why they should develop in C++. When dealing with limited memory and processor power of a cell phone, you want speed and low level languages such as C / C++ can achieve such a goal

[RedClownKnight]

C++ crap?

lol

the wannabe programmers I presume.

[mlanovoy]

@RedClownKnight C++ as language is indeed crap. Altho, it's only really viable (a long with pure old C) language to develope on a system low level; and performance critical application.

[RedClownKnight]

yea Android is great, linux core, blah blah blah

But Give me C/C++ or give me Death!!

[roxer2b]

NDK for android? :)

[mlanovoy]

Why do you need such crap like C++ when you have awesome SDK and much better language.

Good luck doing something like this guy showed on unmanaged platforms/native languages.

[zenhemmo]

Well, if C++ is crap then I don't know what Java is....

Tho I absolutely love Android, I hope they make it possible to compile and run native C/C++ binaries (at the expense of portability, of course).

[mlanovoy]

@zenhemmo Java is by far better than C++ as language. Altho, Java is inferior to such languages as C#, Scala, Nemerle, F#, Python, Ruby ect

[zenhemmo]

mlanovoy,

are you joking? C++ is a compiled language, Java is an interpreted one. By its nature, C++ exceeds Java in performance many times. Why do you think system programming is done in C++, never in Java? And comparing languages like you do is meaningless, because every language has its own place.

[mlanovoy]

@zenhemmo Well, you need to get some clue regarding "compiled" "interpreted" next time before you make any judgements.

Java is NOT interpreted language. Java programs are compiled into intermediate form - bytecode - which is then compiled (!) into machine codes, machine codes being executed just like for any unmanaged program - by CPU and NOT by interpreter as you seem to think in your delusion.

[zenhemmo]

mlanovoy,

you are correct about Java code being bytecode, I meant to say that Python is a interpreted one (as you mentioned it on your list). The speed difference can be clearly seen in algorithms - C/C++ compilers generate way more efficient code than Java ever does. Not to mention that C++ allows low level access and direct memory access (Java has a garbage collector).

[mlanovoy]

@zenhemmo There is different measures of efficiency. Very few situations where C++ code will really be "way more efficient". Java programs for example are more efficient than C++ because they consume much less storage (I'm speaking about their size). For such devices as phones with limited size of ROM it may be more critical than insignificant 10% difference in speed of computation (0.09 instead of 0.1 seconds for example for some rarely called but heavy function).

[mlanovoy]

@zenhemmo As for perfomance Java in fact MAY be slower but not more then 200-300%. It may be noticable for very few tasks. Usually it's CPU heavy computations such as math/cryptography/games for majority of other apps the difference is insignificant.

In fact on certain tasks Java may even outperform C++.

[mlanovoy]

@zenhemmo As of system programing - I personally KNOW unlike you why it's done in C (and not C++ as you think, btw) - it's NOT because of performance its because C is very low level language where you can directly work with system heaps/stacks, access IO ports ect, which is impossible (almost) for managed environments.

And, btw, if you think that system programming may not be done in managed, go check Singularity.

[mlanovoy]

@zenhemmo Anyways, I was comparing LANGUAGES not execution environment and not the compiled code. As *language* C++ is fugly. Even new C++0x standard for which is still in development is too an ugly language. And by language I mean language syntaxis.

[PhatPazzo]

Good trolling, but there has actually been C++ implementations since 1.5. Not used to often since it destroys the great point of using java.

[megoogler]

"seamless" ... lol ... is he an X-Microsoft employee?

[mortenlu]

Seamless is bad now?

[Artie562]

thank you very much for this vid!!!!

I was asking myself that question...!!!! how do I shut down apps so my system won't slow down... and i couldn't find the answer to the question in any of the vids, until now...

i was too used to microsoft.... now that i don't have to worry about that with my g1.. fucke yea!

[apetpg]

where can i download the slides shown in the background?

[alqods1]

we need flash player,,flash player flash flash flash flash flashhhhhhhh playerrrrrrrrrrrr mannnnnnnnn

[danielpineros]

i think i prefer the iphone. No offence but is better, this is like a copy of it

[wfox]

1. Android is a platform, not a cellphone.

2. Copy? do a research first and then talk about the platform man.

No offence :).

[frostmaster77]

don't try to be nice, just tell him hes stupid hehehe!

just jocking. He don't now any thing about android.

I was introduced to Android only few hours ago and I'm in love. I'm at 76% downloading SDK of android. hehe :D

[pbpenguin5]

ok i do love this product right now, but does anyone know how much one of these will cost?

[Mastakilla91]

its open source -.-' ^^

[morenoh149]

lol, I think he meant the hardware it'll run on. A phone with these capabilities may cost $400+. There are rumors that the first ones will be available early 2009.

[pbpenguin5]

ok thanks

[wiicow]

I sure hope it dosn't cost that much. other wise it can take a backseat with the iphone as far as i'm conserned.

[ericunderscores]

I'll update this comment for people still viewing this.. Oct 22nd. Tmobile G1 for $180.

[davidmaxwaterman]

when the user's looking at the maps application and 'presses' back, why isn't there any state saved for the maps application? where does the maps application 'go'? what if the user had changed something that they would like to see again next time they launch maps? is this a different scenario and so the app needs to save its state in some other way?

[neoberlin22]

because when you travel back in time you are able to change the future. therefore you need to create a new state when you click on a different adress (or even the same). only the opportunity to do something different makes it neccessary to kill the maps state. am i clear? sorry for my english, i am german :-)

[davidmaxwaterman]

Why does the activity manager in the system process have the mail icon at the start, when there's no mail process? Is it because the mail application has a service which has been killed - and will presumably be launched again when it is time to check mail? If that's the case, why doesn't it have any state saved in it? ...but then there's nothing in the 'mail process' when it's created (should have something to represent a server along side the activity, no?).

It's confusing me. Any ideas?

[davidmaxwaterman]

..no, I'm wrong. The mail 'activity' that's in the activity manager part of the system process is the 'mail list' activity, and it's created *before* the mail process itself. If it was from some previous instance of the mail process it would have some saved state on it, but it doesn't....weird.

Either I'm very confused, or it's a 'typo' on the video (or both).

[davidmaxwaterman]

ah, the 'extra credits' part of the NotepadCodeLab helps a lot. There's nothing like actual code and a debugger to explain things :)

[samunai]

I know, these guys know lot about me and their information hunger is getting bigger and bigger. BUT I LOVE GOOGLE!!!11 The applications they are developing are very good documented, so everyone can learn their products fast => google gets more popular...

[CM3PTb]

Hi everyone!

I think i got how it works... now i have a question - what if that saved state will contain some data, wich leads to an error in application?

Then user will navigate to such an application again, even if process is restarted, and... bang! we got same error again and again. User will never be able to use that app, will he?

[danthelewis]

From this admittedly brief explanation, Mike explained how Back works but not Forward.

You can probably do this by saving the last user interaction (the one that launches the next activity) with the rest of the state information, then restoring it when you go back to the application. Is this built in?

[protozone]

You're thinking of this as being like a web browser, but that's a confusing way of thinking about this.

What is being discussed is what happens in the background when one Android application loses focus and another gains it.

It's basically a really long way of saying "when an Android application loses focus, its state gets saved, and when an Android application regains focus, its state gets restored."

There's a few other details in there, but that's the main message in this video.

[danthelewis]

The whole point of having Back is so that I and the other millions of users do indeed think of this as being like a web browser. It's so the users can pick up on the interface without thinking about how it's implemented.

You don't import a user interface metaphor like Back and then make it leak by breaking Forward. This is asking for confusion.

Is there a big reason not to have a forward stack to go with the back stack?

[protozone]

This isn't something that users will ever see. This is a video for developers. It is not possible for there to be a "forward stack," and when we say "back," we are not talking about the same type of "back" that you see in web browsers.

[giacomolg]

Why do you save the HOME state if the process is never going to be terminated ?

[shonzilla]

That's a good question.

At 2:20 Mike explains activity states are stored "if something bad happens" which is either freeing up memory when there isn't enough of it or when application crashes.

I guess that might happen with Home application as well, since it takes up memory as well and nobody's perfect. ;-)

[protozone]

Sounds like the Home application is a special case.

There is probably a limit to how much memory it will ever need, and since every other application is considered "less important" than the Home application, it should never need to be killed.

[NightSun666]

Really good question,

i explain to you using the example of PC-OS, like Windows. You always have a way to dump the state of memory, and so of your machine, for management and fixes, this means you ALWAYS have an image of ALL processes saved into the memory, for a "work saving" scope.

This is the HOME state, i think.

[jeremyfoo]

Great use of keynote 08 :)

[ferrell]

Hmmm...I know this is just an example, but it seems like it would be better to have MORE MEMORY than to simply start killing processes. For instance. If I'm doodling around in the maps application as shown, it would be nice to have my mail app periodically check the server for new messages.

[necrodome]

There is a component called Service, which is described in building blocks. It basically do what you want, run in background and doesn't killed except if the phone is on extremely low memory.

[argladd86]

can't wait to see some actual platforms for this...

[hoofmen]

I'm already thinking about "the killer app"

[vatd112]

wow

[travischoma]

pretty exciting!