EECS2030 Test 4

Instructions

There is one programming question and three other questions.

Programming question

Implement the Table class. A skeleton can be found here. The API can be found here. A jar with the Furniture and Leg classes can be found here.

You have to put your Table class in the test4 package.
You have to implement inheritance and composition.

Other questions

Question 1

The UML diagram
denotes that (select the best answer)
A. Classes A and B are in the aggregation relation
B. Classes A and B are in the inheritance relation
C. Classes A and B are in the composition relation
D. Classes A and B are in the usage relation

Question 2

To delegate to the constructor of the super class, one uses the keyword

Question 3

Consider the following classes.

public class CreditCard
{
   private double balance;

   /**
    * Checks if the balance of this card is positive.
    *
    * @throws Exception if the balance of this card is not positive.
    */
   public void checkPositive() throws Exception
   {
      if (this.balance <= 0)
      {
         throw new Exception("Balance is negative");
      }
   }
}

public class RewardCard extends CreditCard
{
   private int points;

   /**
    * Checks if the points balance of this card is positive.
    *
    * @throws Exception if the points balance of this card is not positive.
    */
   public void checkPositive() throws Exception
   {
      if (this.points <= 0)
      {
         throw new Exception("Points balance is negative");
      }
   }
}

Point out what is wrong in the above code. ("Use this.getBalance() instead of this.balance" is not the answer.)