hello, Ron!

how can I help you today?

Hi Mark. Trying to get an API key for MapsV2 that covers both debug and deployment. I'm on page 1035 of your 5.6 book. Don't see "Registered Apps" on the left navigation bar of the Google Cloud Services

yeah, they changed that site, again

(grumble, grumble, grumble)

hold on a second while I pull it up

click "Credentials" in the "APIs & auth" area

if you have enabled the Maps V2 API (in "APIs" under "APIs & auth"), you should have a red "CREATE NEW KEY" button

that will pop up a dialog where you can enter signing key/package name pairs

(after first choosing "Android key")

So far, so good. Got the enter pairs screen...

fill them in, click "Create", and you're set

So I have to run keytool against my keystore(s)?

to get the signing key fingerprint, yes

that's covered in "Your Signing Key Fingerprint(s)", on the previous page of the book

I have the command there for the debug keystore; you'd substitute your own path, alias, and passwords for production keystores

So I do this twice, once for debug keystore, once for deployment keystore and get a single API key back?

if "this" is "run keytool", then yes

you can paste in both pairs (debug fingerprint + package, production fingerprint + package)

this allows you to use one API for both builds

and saves having to mess around with swapping API keys between debug and production

which was a serious pain in various body parts back in the Maps V1 days...

Great. That's what I was hoping for. It will take me a while to work through it.

Today, I wish there were more people for you to talk to ....

it's an unusual time slot

most chats are Tuesday and Thursday

I am unavailable next week, so I added a third chat this week

if you have another question, go right ahead

No, I'm all set for now. I have to work through getting the fingerprints. Not that urgent, if I have issues I can wait a couple of weeks. Thanks!!

hello, EGHDK!

EGHDK: do you have a question?

Yep.

I have two activities and one custom class on top of that in my app. When I go from activity A to B, I create a new CustomClassObject and I pass it a context. In this class, I use the context to finish activity B when something happens. My problem is that I'm using a static variable in activity B and even though I have finished activity B, if I go back, my static variable is still set to whatever I have changed it to. Hope that wasn't too confusing.

that's how static data members work in Java

what are you expecting to happen?

Okay, let me expalin again and what I thought was going to happen.

Go from activity A to B. In B I have a static data member, that get's toasted when the activity Resumes (just so I can check the value of the static variable. I finish the activity, and I'm back at A. I open B from A again, and it still has that static member set to what it was before. In my head. The Activity was finished, so none of the variables in there should exist anymore, therefor when creating a new intent, I should get a new instance of this static variable.

why did you make it static?

the behavior you describe is for a *regular* data member, not a static one

sorry, I meant "the behavior you want"

Well, I need to access the static member from the customclass I told you about.

I kind of understand why the static variable sticks around... but that got me thinking. Does that mean that ENTIRE activity B is still in memory?

no, you need to access the *data* from the custom class

you *chose* to use some static data member to do that

you are welcome to choose something else

for example, make it a *regular* data member, with a getter method (getWhateverTheHellThisIs())

then, have your custom class hold a reference to the activity

or, simply pass the data into the custom class in its constructor

and I'm sure there are other possible patterns, but since I do not know anything much about this "custom class", I cannot advise you further

in terms of whether your instance of Activity B is still in memory, I don't know, because I have no idea what this static data member is

It's just an int.

then that will not hold a reference back to the Activity B instance

and so the Activity B instance is not reachable from this static data member

But if it were something else... does that mean my instance of B would still be in memory?

it depends upon what "something else" is

Any examples?

Would it just have to be an object?

if "something else" holds a reference back to the instance of Activity B, then yes, the static data member will be able to reach the Activity B instance, and the Activity B instance cannot be garbage-collected

so, for example, if you inflate a layout in Activity B, and take a widget from that layout (findViewById()), and put that widget into a static data member, you're in trouble

because widgets hold the activity they belong to

and so the static data member references the widget, which references the activity

and therefore the activity cannot be garbage collected

How do I know what objects hold the activity they belong to?

in most cases, because you wrote the class in question

this is why using static data members is risky

and needs to be done carefully

So lets say I want to use ActivityB.getMyInt() in my custom class. instead of using a static.

How would I know I'm using the correct instance of ActivityB?

well, where does this instance of this "custom class" live?

is it too a static data member somewhere?

The custom class was started in Activity B.

that does not really answer my question

is the instance of the custom class being referenced from a static data member of Activity B?

or a regular data member of Activity B?

Regular

then how would it ever know about any *other* instance of Activity B?

you wrote the code

you see where you are teaching this custom class instance about the instance of Activity B

That's actually a great point.

Never thought of it that way.

"then how would it ever know about any *other* instance of Activity B?"

I always actually felt indifferent about doing that, because I thought it was creating a new object, and getMyInt from that new object.

That makes sense. Thanks Mark.

if anyone has another question, chime in

So in Activity B I have a method called getMyInt. In activity B I create an CustomClassObject(Context), and then in my CustomClassObject I simply do (ActivityB) ctx.getMyInt(); and that should be it.

even better would be to just hold onto ActivityB directly

rather than pretending it is merely a Context, then casting it back to an ActivityB instance

Aha. Even better.

but, yes, the mechanics are pretty much what you describe

So my constructor in my class should be requesting an Activity as an argument or an ActivityB as an argument?

ActivityB

after all, you *need* it to be an ActivityB to be able to call getMyInt() on it

it does you no good to be passed some other Activity subclass

or some other Context subclass

so, you make as well make Java's strong typing work for you, to prevent bugs where you try passing in the wrong thing

Ah yes. It's all coming together now.

But even if I pass in an ActivityB as a context, and it's only asking for a context, then that activity I pass in, is STILL technically an Activity even though the constructor only asked for a context.

sure

Which is how it allows me to cast it back to an ActivityB if anything.

right

Great.

Making progress. haha. Thanks again Mark. Almost through my first java book. I can see clearly now.

The rain is gone.

the rain

is still here, though it will hopefully have passed by this evening

:-)

and that's a wrap for today's chat

the transcript will be posted to http://commonsware.com/office-hours/ shortly

Thanks. See you next week

the next one is not until March 4

March 4 at 4pm US Eastern Time, to be specific

have a pleasant day, all!