You now have completed two of the three hours devoted to object-oriented concepts in this tutorial. You've learned how to create an object, give behavior and attributes to the object and its class of objects, and convert objects and variables into other forms by using casting. Thinking in terms of objects is one of the tougher challenges of the Java coding language. Once you start to understand it, however, you realize that the entire language makes use of objects and classes. During the next hour, you'll learn how to give your objects parents and children.