设置R.drawable的变量

Question

At the moment I set a marker image for google maps on android like this:

.icon(BitmapDescriptorFactory.fromResource(R.drawable.mon1))

Where mon1 is the name of the corresponding to a image called mon1.png in drawable folder.

How can I do it like this:

 String imagename="blablaimage";

.icon(BitmapDescriptorFactory.fromResource(R.drawable.imagename))

Answer 1

If you click over R.drawable.mon1 , you'll find an int declared with the name mon1 in R.java class. Everything resides in R class is basically an int. That said, you can't declare variable imagename as String to begin with. It must be int.

Everything generates in R.java class is auto generated by Android itself. Once you put some resources in appropriate directory, R.java generates corresponding resource int within so that it can be invoked from Java-end.

Bottom line, if you have an image called blablaimage somewhere in your drawable, you can (at best) do this,

int imagename= R.drawable.blablaimage;

.icon(BitmapDescriptorFactory.fromResource(imagename))

Answer 2

It is not possible to do what you suggested.

Instead, a possible workaround might be to use the following function:

public int getDrawableId(String name){
        try {
            Field fld = R.drawable.class.getField(name);
            return fld.getInt(null);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return -1;
    }

and use like:

 String imagename="blablaimage";

.icon(BitmapDescriptorFactory.fromResource(getDrawableId(imagename)));

Answer 3

Another possibility using Resources.getIdentifier :

.icon(BitmapDescriptorFactory.fromResource(
   context.getResources().getIdentifier(imagename, "drawable", "com.mypackage.myapp"); 
));