Use Java's extends keyword to derive a child class from a parent class, invoke parent class constructors and methods, override methods, and more.

I'm getting better with Java, even to the point where I'm almost comfortable with it, but the purpose behind one concept still eludes me: What is method overriding, and why should I care about it?

Override the fill() method header in the same manner as overriding the draw() method header. Listing 9 presents an equivalent Fill application that demonstrates the Fill interface.