Develop Reference

Loading resources from external files

I am working on a localization strategy for our Android product. Once the core product is installed, I would like the user to be able to download additional language packs. Our resources are mainly strings. Essentially, I would like to keep the external file in xml format, similar to how it is done for embedded resources. This way, the translators can also test their translations right away and there won't be any need for sending them back-n-forth.
I am wondering if anyone has done something similar? The biggest challenge I see is that for embedded resources, the key gets converted to a numeric value. For example, getString(R.string.hello) may not work.
On second thought, it would be nice if I can compile the external resource file, similar to what Android framework does when building the .apk file.

Android dynamically load resources

I am trying to use the DexClassLoader to download a JAR/APK in my app. I would like to modularize my app so I can download UI flows the user might go on demand instead of shipping them all together into my main app.
Loading the actual classes works fine and I managed to load some UI components which I can add to my host activity.
My problem is that obviously I cannot access or add resources (Strings, drawables, layouts) to my downloaded package because they do not come with my host APK. Is it possible to dynamically load resources for my downloadable JAR/APK?

You can "dynamically" download any resources you want, put them in a directory you choose, and use them in your app. It's what I currently do in an app. I don't think you can put them in the same directory with the resources that are in your project, but does that matter?

Accessing assets in Android NDK via filesystem

I'm porting a rather large game engine written in C++ from Windows/Mac to Android. There is a lot of pre-existing code to read assets for games. In addition, there is quite a bit of code doing file system calls (stat'ing the files to make sure they exist, looking up all of the files and directories inside of a directory, etc.)
Right now, I'm focusing on just getting something up and running as quickly as possible, so I'd prefer not to have to rewrite a lot of this. What would be a good way of getting our game assets onto the device and accessing them with minimal changes to our existing standard C++ file system API usage?
I've got some basic support implemented already using the Asset Manager API, but that doesn't support the file system calls and I'm concerned that the 1 MB asset size limit is going to bite me at some point.
I've also looked at OBB, but the tools for creating an OBB file don't look like they are part of the current SDK/NDK. Otherwise, that looks like it would be perfect.
Is it a horrible idea to package up all of the files and just extract them on the SD Card the first time the app is run? Or is there some better way of dealing with this?
Update: I'm also not very concerned on being able to run on a broad range of devices, I am specifically looking at newish tablets, probably the 10.1" Samsung Galaxy tab.

We ran into a similar problem in developing our (data-file-heavy) app, and we ended up deciding to keep the APK tiny and simply download our data files on first run; they're going to have to be downloaded either way, but a small APK works much better on older devices without a lot of internal storage. Plus, you can potentially rig up a way for people to copy over the files directly from their computer if they have a limited data plan or a slow internet connection on their phone.
The "Downloader" sample app in apps-for-android (confusingly buried under "Samples") is almost a fully-implemented solution for this - you can pretty much just plug in the particulars of your data files and let it do the rest.

I wrote an app that relies on putting a good amount of native code into the Android filesystem. I did this by packaging the files into the APK as 'resources'. Instead of pushing them to the SD card, you can put then into the application's private namespace, I.E. /data/data/com.yourdomain.yourapp/nativeFolder.
For details on how to accomplish this, you can see my answer to this question.
It's fairly simple to package to just unpack them on the first run and never worry about them again. Also, since they're under the application's namespace, they should be deleted if/when someone were to decide to delete your app.
EDIT:
This method can be used to put anything into the app's private area; /data/data/com.yourdomain.yourapp/
However, as far as I know, your application has to be the one to create all the folders and sub-folders in this area. Luckily this is fairly easy to do. For example to have your app make a folder:
Process mkdir = Runtime.getRuntime().exec("mkdir " +localPath);
That works as it would in most linux shells. I walked through the assets folder I packaged into my APK, made the corresponding directories and copied all the native files to those directories.
What you might be more concerned with is the limited Android shell. There are many commands that you might want that aren't present. stat for example isn't available, so all of this may be moot if your native code can't make it's system calls.

How to protect drawable resource in Android application

Please tell me how to protect our resource in a apk package.
With a simple rename-extract process, any one can copy and thief application drawable resource like images or soundFX files.
My question is, is there any way to protect drawable resource in a Android application?

The drawable needs to be accessible to the operating system, so it has to be readable.
If you really want to keep it secure, you could consider storing it encrypted as a raw asset, then load it, decrypt it into a ByteStream and pass it into the BitmapFactory. That, of course, has slight performance ramifications and will force you to hand-code a lot of stuff that you could have easily done in XML otherwise.
That all aside, there are many ways to steal data - if it's a drawable, people could just take a screenshot.

My question is, is there any way to protect drawable resource in a Android application?
No. Resources are world-readable by design. Even if you were to not package the "images or soundFX files" as resources but were to download them on first run, users with root access could still get to the files.
Since this is not significantly different than any other popular operating system humanity has developed, it is unclear why you think this is an Android problem. Sufficiently interested users can get at your "images or soundFX files" on iOS, Windows, OS X, Linux, and so on. Even Web apps are not immune.

I think it's possible to protect resources. In fact there's low-level class/routine to read resources: AssetManager - ordinary Resources class sits on top those AssetManager. So to protect resource one can scramble resources and read/unscramble them using AssetManager low-level methods: look here

NetBeans and Android image

New to Android development and have decided to use NetBeans 6.9.1 as my IDE. So far the process has been somewhat painful, but I'm getting things rolling. However, I am creating an ImageView subclass for my first custom View and I can't figure out how to add my Box.png file to the project. Drag and Drop doesn't work, there are no right-click options to add a file to the Resources folder, no dropdown menus to add images, no way to add the image to a package. Could use some insight, thanks!

Just go to the project folder and copy the images you want into the res/drawable folder. The IDE helps you a lot with code completion, error checking, etc... but that simple task can be done by hand.
Then, you can reference your resources by using something like: R.drawable.image Notice that I'm not using the image extension. If you wonder what R is, let me give you a brief explanation:
Each resource that is saved in the resources directory is referenced in the R class. That's a file that is autogenerated by Android and it's used to reference those resources from your code. In this case, it will be in R.drawable.* since it's a drawable resource. There are other kind of resources, like layouts: R.layout.something or strings R.string.whatever. That's essential for the android development, so you better read some tutorials (or buy books) in order for you to get started.
So, in your case will be something like setImageDrawable(R.layout.wood); However, I highly recommend to read first a couple of tutorials. Google about it, you will find tons of them.