Issues related to R file resources can not be referenced

            
R file has this:
public static final class drawable {
public static final int ic_launcher = 0x7f020000;
public static final int widget_battery_bg1 = 0x7f020001;
}
But I was being given such references in the java file:
mImageView.setImageResource (R.drawable.widget_battery_bg1);

Error message:
widget_battery_bg1 cannot be resolved or is not a field