SDSU CS535 Object-Oriented Programming & Design
Fall Semester, 1996
Doc 22, Exam

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San Diego State University -- This page last updated Nov 11, 1996
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Doc 22, Exam Slide # 1Listen Here!

1) a) We have a class A which has a protected field P. Explain where the protected field P is accessible and where it is not accessible.

b) We have a class A which has a field N, with no explicit access level given. Explain where the field N is accessible and where it is not accessible.


2) a) What is a NaN?

b) Under what conditions will a NaN be generated in Java?


3) What is a constructor? When are they called?

b) What is the role of a finalize method? When is it called?


4) What are the differences between an abstract class and an interface in Java?


5) a) What makes an exception checked or unchecked?

b) How can a Java program treat an unchecked exception differently than a checked exception?


6) Let a child and parent class both have a method, public void foo(), with the same signature. The rules for determining which foo() is executed at run time can be summarized as: "overridden methods are resolved dynamically". Explain why hidden fields can not be resolved dynamically.
Doc 22, Exam Slide # 2Listen Here!

7) What is super? Give an example of when you would use "super".


8) We have two classes A and B. What relationship between A and B do the following phrases indicate. Please indicate the role of A and B in the relationship. For example: A is the parent of B.

a) Is-kind-of

b) is-analogous-to

c) has-a


9) True or False. A Java class A has a final field F. All objects created from class A must have the same value for F.

True or False. An access of a non static method is always resolved dynamically.

True or False. The average number of fields per class should be less than 6.

True or False. If a child class constructor does not explicitly call it's parent's constructor, then the parents constructor is not called when creating a child object.
Doc 22, Exam Slide # 3Listen Here!

10) What is the result of compiling and if they compile executing the following programs?
a) 
class  Test
   {
   public static void A()
      {
      int  array[] = new int[5];
      try  
         {
         System.out.println( "Start Try"  );
         array[  10  ]  =  1;
         }
      catch (  Exception error  )
         {
         System.out.println( "Exception " );
         throw error;
         }
      finally
         {
         System.out.println(  "Final Block"  );
         return;
         }
      }
      
   public  static  void  main( String  args[]  )
      {
      try {  A();  }
      catch  (ArrayIndexOutOfBoundsException error ) 
         {
         System.out.println(  "In Catch"  );
         }
      System.out.println(  "After try in main"  );
      }
   }


Doc 22, Exam Slide # 4Listen Here!

b) 
class  Test
   {
   String message = "Global";

   public static void A( String message)
      {
      message = message + "End";
      }
      
   public  static  void  main( String  args[]  )
      {
      String message = "Main";
      A( message );
      System.out.println( message );
      }
   }



Doc 22, Exam Slide # 5Listen Here!


c) 
class Parent
   {
   public Parent()   
      { 
      System.out.println( "Parent" ); 
      }

   public Parent( double value )   
      { 
      System.out.println( "Parent value "  + value );  
      }
   }

class  Child extends Parent
   {
   public Child( String message )
      {
      System.out.println( "Child " + message );
      }
   
   public Child( double value )
      {
      System.out.println( "Child value " + value );
      }

   public  static  void  main( String  args[]  )
      {
      Child A = new Child( 5.5 );
      Parent B = new Child();
      }
   }


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