Android (min 2.1): load images from name string

Question

I want to be able to load images dynamically from res/drawable. I don't how many files there will be, but I do know they will be named by convention as "image_N", where N is sequential integer. It is possible that new images will be uploaded while the app is running.

My code is basically

Resources rs = getResources();
String imgName = "android.resource://" + this.getPackageName() + "/drawable/image_" + i;
int imgID = rs.getIdentifier(imgName , null, getPackageName());

if (imgID != 0)
{
    Drawable d = rs.getDrawable(imgID);
    //etc.
}

but imgID being returned is always 0.

I also tried another approach

String imgName = "android.resource://" + this.getPackageName() + "/drawable/image_" + i;
b = BitmapFactory.decodeFile(imgName);
if (b != null)
//etc

But b is always null.

I know there are files in the folder with the right names because I put a few there. Not sure what I'm doing wrong. Any help would be greatly appreciated!

score 2 · Answer 1 · answered Mar 06 '12 at 03:00

2

I believe you are using getIdentifier(...) incorrectly. This should work:

int id = Context.getResources().getIdentifier("image_" + i, "drawable", getPackageName());

which would is equivilent for an id R.drawable.image_<+i>

answered Mar 06 '12 at 03:00

triad

20,407
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My final code does indeed have a line that looks like that. :) Thanks! – Sabrina S Mar 06 '12 at 03:41

score 0 · Answer 2 · answered Oct 30 '15 at 15:01

in Adapter i use this

   Context context;
   public MyAdapter0(Context context, 
   List<String>   moduleList,List<String> moduleList2) {
   mInflater = LayoutInflater.from(context);
   for (int i=0;i<moduleList.size();i++) {
   int id = context.getResources().getIdentifier("color6_"+i,
   "drawable", context.getPackageName());
    mItems.add(new Item(moduleList.get(i),moduleList2.get(i),id));
   // Log.d("idimage", String.valueOf(R.drawable.color6));
    }

score 0 · Accepted Answer · answered Mar 05 '12 at 23:54

0

I think you've mistaken compiled resources with files inside folders. In Android, resources are static as far as I know. Once compiled you can't add new resources by dropping files inside "drawable" folder, there would be no IDs for new files. You should use a folder in DATA or better ask Android API with getFilesDir() or something similar.

For more info, take a look >>here

answered Mar 05 '12 at 23:54

ruhalde

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Ah! Thank you. If that's true, it makes things simultaneously easier and more difficult for me. :) The default images that I put in my res/drawable I should just be able to refer to directly (perhaps via a foreach statement?) while the others I will need to go through the file resources - or perhaps the load through URL API. – Sabrina S Mar 06 '12 at 01:48
For the default list of images in R.drawable, I found that part of the solution (here)[http://stackoverflow.com/a/3950277/1181368]. – Sabrina S Mar 06 '12 at 03:33

score 0 · Answer 4 · answered Mar 06 '12 at 00:01

0

I use this:

String drawableName = "drawableNameAsDeclaredInDrawableDir" // in your case "image_" + i;
int drawableResId = resources.getIdentifier(packageName + ":drawable/" + drawableName, null, null);

Then use

Drawable d = resources.getDrawable(drawableResId);

answered Mar 06 '12 at 00:01

YuviDroid

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Btw as ruhalde pointed out you cannot add drawable resources at runtime. You will have to load new images on the sd card or internal memory. – YuviDroid Mar 06 '12 at 00:08
Hi YuviDroid - thanks! But your code is basically identical to mine, no? Except it looks like you leave out `"android:resource//"`. – Sabrina S Mar 06 '12 at 01:44

Android (min 2.1): load images from name string

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