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Is getResources().getIdentifier() method efficient enough to use it in a ListView?

Some information about the app:
The app contains a lots of images in drawable folder.
The size of every image is between 1kb and 3kb.
And I need to draw them into a ListView.
What I need to get:
I need store the identifier of the image (R.drawable.my_image) into database with some aditional user information.
The problem:
When I update the app (adding new image resources), the identifier may change. So, in database I will have an outdated identifier, which is linking to a non-existing resource.
I've thought to store the resource name in database instead of the resource identifier and them I will retrieve it by getResources().getIdentifier(String, String, String) method. But I don't know if this method is efficient enough to use it in a ListView.
The documentation says Note: use of this function is discouraged. It is much more efficient to retrieve resources by identifier than by name.
Do you know any other solution?

Finally Im using getResources().getIdentifier() method to load images into list (with recyclerview). My list has about 20 images. The average size is also less than 3kb. I've tried the app in older devices (wich behavior can be affected by his CPU) and it worked fine. I know this method is not recomended, but can be a solution.

Not efficient to use it in a list view.
Official documentation of Resources.getIdentifier method:
Return a resource identifier for the given resource name. A fully qualified resource name is of the form "package:type/entry". The first two components (package and type) are optional if defType and defPackage, respectively, are specified here.
NOTE in documentation
Note: use of this function is discouraged. It is much more efficient to retrieve resources by identifier than by name.

Android: Is it possible to alias R from app and lib to distinguish between the two?

Can I somehow alias a generated R file from a library and a generated R file from an application?
IE: I have two projects, one being a library. I reference the library in the application.
The library creates one R file, the application creates two: com.example.mapplication.R and the R from the referenced library, com.example.mlibrary.R. However, since I want to use both frequently in the application, I want to alias both the R classes. For example, call the library R something like libR and the app R something like appR.
I tried a couple of things which are of such stupidity, I won't even fully mention them, but I did some things like private com.example.mapplication.R appR = com.example.mapplication.R (immediately realising this wasn't gonna work), and private Class<com.example.mapplication.R> appRclass = com.example.mapplication.R.class;, but that didn't give me the desired effect. I do, however, use the latter method and some reflection to make it possible to be able to get the field and inner classes like this:
Class<com.example.mapplication.R> appRclass = com.example.mapplication.R.class;
int activity_main_layoutid = Toolkit.getFromClass(appR).
getMeTheInnerClass("layout").getMeAField("activity_main");
I haven't fully implemented the Toolkit method, but as we all know refletion can do this kind of stuff, but at the end of the day it's just as much work as just typing com.example.mapplication.R or com.example.mlibrary.R everywhere.
So to wrap thing up: Is it possible to alias multiple R's so that I can use appR and libR to distinguish the two?

I wish we could, but according to what I know, it isn't possible, at least not yet.
I also wish we could put resources in sub folders, but even this is impossible.
What you can do is setting a unique prefix (rename each resource file) for each library, as it's done by some third party libraries (like actionBarSherlock, which uses "abs" as the prefix).
Alternatively, you can have a special trick and put the files in the src folder and reach them from there, but that's more of a workaround, since the R won't have a reference to any of the resources there.
For example, you can put an image called image.png into the src/com/company/app_name, and then create a bitmap from it using:
final InputStream fis = getClass().getResourceAsStream("/com/company/app_name/image.png");
final Bitmap bitmap = BitmapFactory.decodeStream(fis);
By the way, if you've thought of using the assets folder, you can't do it for library projects, since it requires you to have the files in the project that uses the library project. It will work, but it misses the encapsulation idea...

Benefit of Declaring String as Resource in strings.xml file

I have read in many places that you should declare your String objects in your resource file but I haven't read about any benefits anywhere.
I have already declared all my Strings that I have in my layouts as resources but I haven't done so in my classes.
My question is:
What are the benefits of declaring Strings as a resource? Are there any memory benefits?

Internationalisation,
Keeping all of your strings in a single place (where they can be editted globally),
Changing strings based on device (mdpi/large/portrait)... I mean, it'd be really rare for this
last one, but it's possible.
Sharing the same string among many layouts (this will happen in any app which isn't tiny)

The top one I reckon is: Translations! Put a new strings.xml in the right folder and the app translates itself for each device.
But there's a matter of organisation too. Just like the layout, you normally don't build in the code, because that's not the place for it.
The code is to process stuff. The string is just one more of the resources that your code will use to show stuff on the screen.

One of the main benefits is for localization: you keep your code language-independent and just need to provide a different XML file for each language you want to support.

Way to group resources

I'd like to group my drawables in some way that doesn't involve some crazy approach (for example reflection on the generated R class).
For example I have 10 types of some object in a game. I'd like to load them all into an array without actually copying:
enemy[0] = resources.getDrawable(R.drawable.enemy_image_0)
enemy[0].set....
enemy[1] = resources.getDrawable.....
Is there some way to group them and load in a loop? Any way to do that without getting into how R is generated and changing its structure?

Is there some way to group them and load in a loop?
Use getIdentifier() on the Resources object (which you typically get via getResources() on your activity or other Context).
Since this, under the covers, uses a "crazy approach" (specifically "reflection on the generated R class"), and since reflection is not especially speedy, please cache these values where possible.

Android: Loading multiple images

I have recently started developing a game in android, never used it before and was wondering if there is a simple way of getting a set of images loaded into the application. As my current implementation involves basically
Creating an int[] array,
Storing the values of each drawable into this array, (now this has to be hand coded, so if I add any more images it has to be added programmitically)
Then itterating through each item in the array and calling BitmapFactory to get the resource.
(Unfortunately I don't have the code with me as it is at home and I am at work, but that is the jist)
So 2 questions, is there a way of getting the drawables without having to put in each item manually to the int[] - ie looking for perhaps a file name prefix and then only loading the resource with the prefix?
Which leads me to my second question because I more than just these images in my drawable resource directory, is there a way to add extra organisation (folders) to manage the files better. As currently I have loads of images within the drawable file and how would I reference these sub folders/images.

You cannot have sub folders within the resources structure. Android depends on the folder layout to determine which resource to use in what condition (localization, different screen resolutions, etc).
I'm not sure why exactly you are trying to load up a whole bunch of images, but there are a couple of (slower) methods that allow you to look up a resource by string name. If you used a naming convention for your images you could look them up that way via [Resources.getIdentifier()][1]. However, in a game performance likely matters, so you are probably better off with a more manual approach using the int IDs directly since it is much more efficient.
[1]: http://developer.android.com/reference/android/content/res/Resources.html#getIdentifier(java.lang.String, java.lang.String, java.lang.String)

I am uploading a load of images as they will be shown to user for different items. Its not a system where responsiveness is critical so its okay in terms of what I want. Though...
public int getIdentifier (String name, String defType, String defPackage)
Since: API Level 1
Return a resource identifier for the given resource name. A fully qualified resource name is of the form "package:type/entry". The first two components (package and type) are optional if defType and defPackage, respectively, are specified here.
Note: use of this function is discouraged. It is much more efficient to retrieve resources by identifier than by name.
They suggest using the resource id but if I want to add a file later on then I have to re-compile the app to include the extra file, this is where it bugs me, as the pic gets associated to an item that I have in a string array. So I can add items to the array but not the images without a change of the code.
Surely there is a function to fix this?