Topics list for Second Semester Midterm 1

• Interfaces and Polymorphism
  • When to use interfaces or classes
    • Mobile problem illustrated use of Structure as interface--it's just about methods, not fields
    • Animal was a class because it stored weight and name
      • super(parameter_list) calls superclass constructor
      • super.method(parameter_list) calls a method in the superclass
      • Superclass default constructor is created by Java if one is not explicitly written by the programmer
      • Object is the superclass of any class that does not explicitly extend another class
  • Comparable<T>
  • Cow array example (class Cow implements Comparable<Cow>)
  • Animal array example (lots of different animals extending Animal in array, class Animal implements Comparable<Animal>)
• Inheritance and Delegation
  • GridWorld examples
  • TriangleBug extends Bug extends Actor (implicitly extends Object)
    • TriangleBug inherits the properties of Bug
    • TriangleBug delegates methods it does not know how to do to Bug
  • KnightCritter extends Critter extends Actor (implicitly extends Object)
• Binary Search Trees
  • NullPointerException (i.e., making sure objects are not null before using them
• Randp