Is resource a color or a drawable?

Issue

I have create a little custom view that extends ImageView. My custom view provides a method showError(int), where I can pass a resource id, which should be displayed as the image views content. It would be great if I could pass a simple color resource id or a drawable resource id.

My problem is: how do I determine if the passed resource id is a Drawable or a Color?

My current approach is something like this:

class MyImageView extends ImageView{

     public void showError(int resId){

        try{
            int color = getResources().getColor(resId);
            setImageDrawable(new ColorDrawable(color));
        }catch(NotFoundException e){
            // it was not a Color resource so it must be a drawable
            setImageDrawable(getResources().getDrawable(resId));
        }

     }
}

Is it safe to do that? My assumption is, that a resource id really unique. I mean not unique in R.drawable or R.color, but completely unique in R

So that there is no

R.drawable.foo_drawable = 1;
R.color.foo_color = 1;

Is it correct that the id 1 will be assigned only to one of this resources but not to both?

Solution

You probably want to look up a TypedValue from the resources, to allow you to determine whether the value is a Color or a Drawable. Something like this should work without needing to throw and catch an exception:

TypedValue value = new TypedValue();
getResources().getValue(resId, value, true); // will throw if resId doesn't exist

// Check whether the returned value is a color or a reference
if (value.type >= TypedValue.TYPE_FIRST_COLOR_INT && value.type <= TypedValue.TYPE_LAST_COLOR_INT) {
    // It's a color
    setImageDrawable(new ColorDrawable(value.data));
} else if (value.type == TypedValue.TYPE_REFERENCE) {
    // It's a reference, hopefully to a drawable
    setImageDrawable(getResources().getDrawable(resId));
}

Answered By - Alex MDC