CSCI A201/A597 Takehome Quiz Three Second Summer 2000

Questions:

1. Explain the difference between an object and a class.

2. Give the Java code for an
   • object of class BankAccount and
   • for an object variable of class BankAccount.

3. Explain the differences between an instance variable and a local (or method) variable.

4. Explain the difference between

   new BankAccount(5000); 

   and

   BankAccount b;

5. What are the construction parameters for a BankAccount object?

6. What is default construction?

7. Give Java code to construct the following objects:
   • A square with center (100, 100) and side length 25
   • A bank account with a balance of $5000.
   • A console reader that reads from System.in

   Write just objects, not object variables.

8. Repeat the preceding exercise, but now define object variables that are initialized with the required objects.

9. Find the errors in the following statements:

   Rectangle r = (5, 10, 15, 20); 
   
   double x = BankAccount(10000).getBalance(); 
   
   BankAccount b;
   b.deposit(10000); 
   b = new BankAccount(10000);
   b.addCoins(new Coin(0.25, "quarters")); 
   
   Purse p = null; 
   p.addCoins(new Coin(0.25, "quarters")); 
   
   Purse p = new Purse(); 
   p.addCoins(new Coin()); 
   

10. Describe all constructors of the BankAccount class. List all methods that can be used to change a BankAccount object. List all methods that don't change the BankAccount object.

11. What is the value of b after the following operations?

    BankAccount b = new BankAccount(10); 
    b.deposit(5000);
    b.withdraw(b.getBalance() / 2); 

12. If b1 and b2 store objects of class BankAccount, consider the following instructions.

    b1.deposit(b2.getBalance());
    b2.deposit(b1.getBalance());

    Are the balances of b1 and b2 now identical? Explain.

13. What is the this reference?