Example questions for part II of the exam

• Programming assignments will occur, often with design patterns.
• Question nr 4 from Övning 4. English question is available.
• Questions 1-4 from Övning 5 except to write the DTD. To write XML consistent with a given DTD is a possible exam question.
• Questions 1-5 from Övning 6 The questions are not in english!
• In a library you find the classes FantasyMirror and MagicMath. The two classes cover almost all the functionality you need for a new class in the adventure game that you are planning to write. Your first plan is to write a new class that inherits from both library classes. You realize that Java does not support multiple inheritcance. How do you write a class that uses the functionality of the two library classes ?

• Below are two attempts to implement the Singleton pattern. Both contain a mistake. Explain what is wrong with each of them. Look at the classes separately. If you look at them together it is an easier task.

  class Singleton {
      private Singleton theInstance = new Singleton();
      
      private Singleton() { }
  
      public static Singleton getInstance() {
          return theInstance;
      }
  }
  
  
  class Singleton {
      private static Singleton theInstance = new Singleton();
      
      private Singleton() { }
  
      private static Singleton getInstance() {
          return theInstance;
      }
  }