I'm working on a web development project, and I'm working on several apps with "news feed" functionality. I want to make sure that every item with a picture flips a switch back and forth, so that pictures alternate on the left and right, even if some items in between didn't have pictures. So, I created an interface:
public interface TextWithImageTile {
public abstract String getOrientation( ) ;
public abstract void setOrientation( String orientation ) ;
}
Now, all of my "news feeds" use news items implementing that interface, regardless of whatever custom fields each one uses. So, I had expected to be able to instantiate this utility class to process lists of items implementing that interface:
public class AlignmentAssigner {
List<TextWithImageTile> listToAssign ;
public AlignmentAssigner(List<TextWithImageTile> list) {
this.listToAssign = list ;
}
public void alignList( ) {
for ( TextWithImageTile listItem : listToAssign ) {
...
}
}
}
But now, when I try to send it a List of HomeItem classes - which implement the TextWithImageTile interface - it complains of a type mismatch. Here's the implementation:
List<HomeItem> homeItems = homeDAO.getHomeItems();
AlignmentAssigner alignmentAssigner = new AlignmentAssigner( homeItems );
I'm told that, "The constructor AlignmentAssigner(List) is undefined." Do I have something crossways here? Is it possible to have a method process all implementations of a particular interface, so long as it is only asked to operate on fields and methods defined by said interface? If so, how - or what needs to be changed in my code?
