Hello, I'm studying for my SCJA using McKenzie's book, and I just came across something strange. On page 163, the Full Shapes Class Diagram shows the relationship between Line and Shape using a dotted line (and it uses a dotted line again to represent the relationship between Point and Shape).
However, the "UML for the Java Associate" document that I downloaded from this forum (by the same authors who did Head First Java), says that dotted lines are used when a class implements an interface. It means "implements" rather than "extends".
If you look at the code for Line and Point in McKenzie's book, a few pages before, they clearly "extend" Shape, they don't "implement" it.
Is this a mistake in the book? Or is there another explanation for it?