CODEWITHSUNDEEP
androidcollectionsresourcesdrawable
Matt Huggins
Matt Huggins

Reputation: 83269

Retrieving all Drawable resources from Resources object

In my Android project, I want to loop through the entire collection of Drawable resources. Normally, you can only retrieve a specific resource via its ID using something like:

InputStream is = Resources.getSystem().openRawResource(resourceId)

However, I want to get all Drawable resources where I won't know their ID's beforehand. Is there a collection I can loop through or perhaps a way to get the list of resource ID's given the resources in my project?

Or, is there a way for me in Java to extract all property values from the R.drawable static class?

Upvotes: 26

Views: 33278

Answers (12)

Oliver Metz
Oliver Metz

Reputation: 3748

A possible Kotlin + Jetpack Compose solution would look like this. Note that this one also filters only the drawable that contain the name "icon" but one can also just leave away the filter:

val iconResourceIds = R.drawable::class.java.fields.filter { it.name.contains("icon") }.map {
    LocalContext.current.resources.getIdentifier(it.name, "drawable", LocalContext.current.packageName)
}

One can then draw all icons with their resource names and DP sizes like this:

LazyVerticalGrid(
    modifier = Modifier.background(Color.White),
    columns = GridCells.Adaptive(minSize = 100.dp),
    contentPadding = PaddingValues(18.dp),
    verticalArrangement = Arrangement.spacedBy(32.dp),
    horizontalArrangement = Arrangement.spacedBy(18.dp),
) {
    items(iconResourceIds) { iconResourceId ->
        Column(horizontalAlignment = Alignment.CenterHorizontally) {
            val painter = painterResource(id = iconResourceId)
            Icon(
                painter = painter,
                contentDescription = null,
                tint = Color.Black
            )
            val name = LocalContext.current.resources.getResourceEntryName(iconResourceId)
            Text(
                text = name,
                color = Color.Black,
                textAlign = TextAlign.Center,
            )
            val widthDp = with(LocalDensity.current) { painter.intrinsicSize.width.toDp() }.value.roundToInt().toString()
            val heightDp = with(LocalDensity.current) { painter.intrinsicSize.height.toDp() }.value.roundToInt().toString()
            Text(
                text = "$widthDp x $heightDp",
                color = Color.Black,
                textAlign = TextAlign.Center,
            )
        }
    }
}

Upvotes: 1

Jens van de Mötter
Jens van de Mötter

Reputation: 940

To create an array of drawables in Kotlin:

    val drawablesFields: Array<Field> = drawable::class.java.fields
    val drawables: ArrayList<Drawable> = ArrayList()
    for (field in drawablesFields) {
        context?.let { ContextCompat.getDrawable(it, field.getInt(null)) }?.let {
            drawables.add (
                it
            )
        }
    }

Upvotes: 0

user7616371
user7616371

Reputation:

USE THIS MY CODE

R.drawable drawableResources = new R.drawable();
Class<R.drawable> c = R.drawable.class;
Field[] fields = c.getDeclaredFields();

for (int i = 0, max = fields.length; i < max; i++) {
    final int resourceId;
    try {
        resourceId = fields[i].getInt(drawableResources);
        // call save with param of resourceId
        SaveImage(resourceId);
    } catch (Exception e) {
        continue;
    }
}

...

public void SaveImage(int resId){
    if (!CheckExternalStorage()) {
        return;
    }

    Bitmap bmp = BitmapFactory.decodeResource(getResources(), resID);
    try {
        File dir = new File(path);
        if (!dir.exists()) {
            dir.mkdirs();
        }
        OutputStream fOut = null;
        File file = new File(path, "image1.png");
        file.createNewFile();
        fOut = new FileOutputStream(file);
        bmp.compress(Bitmap.CompressFormat.PNG, 100, fOut);
        fOut.flush();
        fOut.close();
        MediaStore.Images.Media.insertImage(this.getContentResolver(), file.getAbsolutePath(), file.getName(), file.getName());
        Log.i(LOGTAG, "Image Written to Exterbal Storage");

    } catch (Exception e) {
        Log.e("saveToExternalStorage()", e.getMessage());
    }
}

Upvotes: 0

D.Snap
D.Snap

Reputation: 1780

You should use the Raw folder and AssetManager, but if you want to use drawables because why not, here is how...

Let's suppose we have a very long file list of JPG drawables and we want to get all the resource ids without the pain of retrieving one by one (R.drawable.pic1, R.drawable.pic2, ... etc)

//first we create an array list to hold all the resources ids
ArrayList<Integer> imageListId = new ArrayList<Integer>();

//we iterate through all the items in the drawable folder
Field[] drawables = R.drawable.class.getFields();
for (Field f : drawables) {
    //if the drawable name contains "pic" in the filename...
    if (f.getName().contains("image"))
        imageListId.add(getResources().getIdentifier(f.getName(), "drawable", getPackageName()));
}

//now the ArrayList "imageListId" holds all ours image resource ids
for (int imgResourceId : imageListId) {
     //do whatever you want here
}

Upvotes: 7

JohnnyLambada
JohnnyLambada

Reputation: 12826

The OP wanted drawables and I needed layouts. This is what I came up with for layouts. The name.startsWith business lets me ignore system generated layouts, so you may need to tweak that a bit. This should work for any resource type by modifying the value of clz.

public static Map<String,Integer> loadLayouts(){
    final Class<?> clz = R.layout.class;
    Map<String,Integer> layouts = new HashMap<>();
    final Field[] fields = clz.getDeclaredFields();
    for (Field field : fields) {
        String name = field.getName();
        if (
                !name.startsWith("abc_")
                && !name.startsWith("design_")
                && !name.startsWith("notification_")
                && !name.startsWith("select_dialog_")
                && !name.startsWith("support_")
        ) {
            try {
                layouts.put(field.getName(), field.getInt(clz));
            } catch (Exception e) {
                continue;
            }
        }
    }
    return layouts;
}

Upvotes: 1

Alecs
Alecs

Reputation: 2920

Just do this:

Field[] declaredFields = (R.drawable.class).getDeclaredFields();

Upvotes: 2

Mika&#235;l Mayer
Mika&#235;l Mayer

Reputation: 10681

Add a picture named aaaa and another named zzzz, then iterate through the following:

public static void loadDrawables() {
  for(long identifier = (R.drawable.aaaa + 1);
      identifier <= (R.drawable.zzzz - 1);
      identifier++) {
    String name = getResources().getResourceEntryName(identifier);
    //name is the file name without the extension, indentifier is the resource ID
  }
}

This worked for me.

Upvotes: 6

Jan-Terje S&#248;rensen
Jan-Terje S&#248;rensen

Reputation: 14698

I have taken Matt Huggins great answer and refactored it to make it more generic:

public static void loadDrawables(Class<?> clz){
    final Field[] fields = clz.getDeclaredFields();
    for (Field field : fields) {
        final int drawableId;
        try {
            drawableId = field.getInt(clz);
        } catch (Exception e) {
            continue;
        }
        /* make use of drawableId for accessing Drawables here */
    }   
}

Usage:

loadDrawables(R.drawable.class);

Upvotes: 9

mishkin
mishkin

Reputation: 6212

i used getResources().getIdentifier to scan through sequentially named images in my resource folders. to be on a safe side, I decided to cache image ids when activity is created first time:

    private void getImagesIdentifiers() {

    int resID=0;        
    int imgnum=1;
    images = new ArrayList<Integer>();

    do {            
        resID=getResources().getIdentifier("img_"+imgnum, "drawable", "InsertappPackageNameHere");
        if (resID!=0)
            images.add(resID);
        imgnum++;
    }
    while (resID!=0);

    imageMaxNumber=images.size();
}

Upvotes: 8

adamp
adamp

Reputation: 28932

If you find yourself wanting to do this you're probably misusing the resource system. Take a look at assets and AssetManager if you want to iterate over files included in your .apk.

Upvotes: 4

Macarse
Macarse

Reputation: 93133

I guess the reflection code will work but I don't understand why you need this.

Resources in Android are static once the application is installed so you can have a list of resources or an array. Something like:

<string-array name="drawables_list">
    <item>drawable1</item>
    <item>drawable2</item>
    <item>drawable3</item>
</string-array>

And from your Activity you can get it by doing:

getResources().getStringArray(R.array.drawables_list);

Upvotes: 3

Matt Huggins
Matt Huggins

Reputation: 83269

Okay, this feels a bit hack-ish, but this is what I came up with via Reflection. (Note that resources is an instance of class android.content.res.Resources.)

final R.drawable drawableResources = new R.drawable();
final Class<R.drawable> c = R.drawable.class;
final Field[] fields = c.getDeclaredFields();

for (int i = 0, max = fields.length; i < max; i++) {
    final int resourceId;
    try {
        resourceId = fields[i].getInt(drawableResources);
    } catch (Exception e) {
        continue;
    }
    /* make use of resourceId for accessing Drawables here */
}

If anyone has a better solution that makes better use of Android calls I might not be aware of, I'd definitely like to see them!

Upvotes: 35

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